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Document:	Guide to VMS 5.0 Files and Devices 198804
Order Number:	AA-LA06A-TE
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Pages:	131
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VMS

Guide to VMS Files and Devices

Order Number AA-LA06A-TE

Guide to VMS Files
and Devices
Order Number: AA-LA06A-TE

April 1988
This guide describes procedures for using files and devices with the VMS
operating system. The tasks described in this manual are oriented toward
the use of private media.

Revision/Update Information:

This revised guide supersedes the
Guide to VAX/VMS Disk and Magnetic
Tape Operations, Version 4.4.

Software Version:

Version 5.0

digital equipment corporation
maynard, massachusetts

April 1988
The information in this document is subject to change without notice and should
not be construed as a commitment by Digital Equipment Corporation. Digital
Equipment Corporation assumes no responsibility for any errors that may appear
in this document.
The software described in this document is furnished under a license and may be
used or copied only in accordance with the terms of such license.
No responsibility is assumed for the use or reliability of software on equipment
that is not supplied by Digital Equipment Corporation or its affiliated companies.
Copyright © 1988 by Digital Equipment Corporation
All Rights Reserved.
Printed in U.S.A.
The postpaid READER'S COMMENTS form on the last page of this document
requests the user's critical evaluation to assist in preparing future documentation.
The following are trademarks of Digital Equipment Corporation:
DEC
DEC/CMS
DEC/MMS
DECnet
DECsystem-10
DECSYSTEM-20
DECUS
DECwriter

DIBOL
EduSystem
IAS
MASSBUS
PDP
PDT
RSTS
RSX

UNIBUS
VAX
VAXcluster
VMS
VT

~Dt1jDIJ~D TM
ZK3389

HOW TO ORDER ADDITIONAL DOCUMENTATION
DIRECT MAIL ORDERS
USA & PUERTO Rico*

CANADA

INTERNATIONAL

Digital Equipment Corporation
P.O. Box CS2008
Nashua, New Hampshire
03061

Digital Equipment
of Canada Ltd.
100 Herzberg Road
Kanata, Ontario K2K 2A6
Attn: Direct Order Desk

Digital Equipment Corporation
PSG Business Manager
c/o Digital§ local subsidiary
or approved distributor

In Continental USA and Puerto Rico call 800-258-1710.
In New Hampshire, Alaska, and Hawaii call 603-884-6660.
In Canada call 800-267-6215.
*Any prepaid order from Puerto Rico must be placed with the local Digital subsidiary (809-754-7575).
Internal orders should be placed through the Software Distribution Center (SDC), Digital Equipment
Corporation, Westminster, Massachusetts 01473.

Production Note
This book was produced with the VAX DOCUMENT electronic publishing
system, a software tool developed and sold by DIGITAL. In this system,
writers use an ASCII text editor to create source files containing text and
English-like code; this code labels the structural elements of the document,
such as chapters, paragraphs, and tables. The VAX DOCUMENT software,
which runs on the VMS operating system, interprets the code to format the
text, generate a table of contents and index, and paginate the entire document.
Writers can print the document on the terminal or line printer, or they can use
DIGITAL-supported devices, such as the LN03 laser printer and PostScript®
printers (PrintServer 40 or LN03R ScriptPrinter), to produce a typeset-quality
copy containing integrated graphics.

PostScript is a trademark of Adobe Systems, Inc.

Contents
PREFACE

SUMMARY OF NEW AND CHANGED FEATURES

xiii

CHAPTER 1 INTRODUCTION TO FILES AND DEVICES

1-1

1.1

THE HISTORY OF FILE STORAGE MEDIA

1-1

1.2
1.2.1
1.2.2

BASIC DEVICE CONCEPTS
Disk Concepts
Magnetic Tape Concepts

1-2
1-2
1-6

1.3

USING COMMAND PROCEDURES TO PERFORM ROUTINE
FILE AND DEVICE OPERATIONS

1-8

CHAPTER 2 FILE AND DEVICE PROTECTION

2-1

2.1
2.1.1
2.1.2
2.1.3

DATA PROTECTION
User Identification Code (UIC)-Based Protection
Access Control List (ACL)-Based Protection
VMS ANSI-Labeled Magnetic Tape Accessibility Protection

2-1
2-1
2-3

2.2

FILE PROTECTION
Volume-Level Protection
Disk Volume Protection • 2-5
Protection of Disk Volumes• 2-6
Magnetic Tape Volume Protection• 2-6
2.2.1.3.1
Protection for VMS Magnetic Tapes• 2-7
2.2.1.3.2
Protection for Interchange Environments• 2-7
File- Level Protection
File Protection • 2-8
2.2.2. 1. 1
Default File Protection • 2-8
2.2.2. 1.2
Explicit File Protection • 2-9
Disk File Protection • 2-9
Directory File Protection • 2-11
2.2.2.3. 1
UIC Directory Protection • 2-12
Magnetic Tape File Protection • 2-1 2
Protection of Mail Files• 2-13

2-5
2-5

2.2.1

2.2.1.1
2.2.1.2
2.2.1.3

2.2.2

2.2.2.1
2.2.2.2
2.2.2.3
2.2.2.4
2.2.2.5

2-4

2-8

Contents

2.2.2.6

2.3

Displays of Ownership and Protection • 2-1 3
DEVICE PROTECTION

CHAPTER 3 PREPARING VOLUMES FOR PRIVATE USE

3-1

3.1

SETTING UP A PRIVATE VOLUME

3-1

3.2

ALLOCATING DISKS AND MAGNETIC TAPE DRIVES TO
YOUR PROCESS

3-1

3.3
3.3.1
3.3.2

INITIALIZING A VOLUME
Initializing a Disk Volume
Initializing a Magnetic Tape Volume

3-3
3-4
3-5

3.4
3.4.1
3.4.2

3-6
3-8
3-8

3.4.4.1
3.4.4.2

MOUNTING A VOLUME
Mounting a Disk Volume
Mounting a Disk Volume Set
Creating a Disk VoAume Set from New Volumes• 3-9
Creating a Disk Volume Set from an Existing Volume • 3-10
Adding Volumes to a Disk Volume Set• 3-11
Mounting a Magnetic Tape Volume
Mounting an ANSI-Labeled Volume • 3-12
Using MOUNT Command Qualifiers • 3-1 2
Mounting a Magnetic Tape Volume Set
Creating a Magnetic Tape Volume Set • 3-16
Mounting Continuation Volumes in a Volume Set• 3-17

3.5

DISMOUNTING A VOLUME

3-18

3.6

DEALLOCATING DRIVES

3-20

3.7
3.7.1
3.7.2

USING COMMAND PROCEDURES TO SET UP VOLUMES
Designing Command Procedures to Set Up Disk Volumes
Designing Command Procedures to Set Up Magnetic
Tape Volumes

3-20
3-21

3.4.2.1
3.4.2.2
3.4.2.3

3.4.3
3.4.3.1
3.4.3.2

3.4.4

2-13

3-11
3-15

3-22

Contents

CHAPTER4 MANIPULATING FILES

4-1

4.1
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5

USING DCL TO RETRIEVE FILE INFORMATION
Retrieving Directory Information
Retrieving Device Information
Retrieving Magnetic Tape Device Information
Retrieving Disk File Protection Information
Retrieving Disk Quota Information

4-2
4-2
4-4
4-6
4-7
4-8

4.2
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.2.6

USING DCL TO MODIFY FILE CHARACTERISTICS
Modifying Directory Characteristics
Modifying Disk File Characteristics
Modifying Magnetic Tape Device Characteristics
Modifying File Protection Characteristics
Modifying User ldentificati·on Code Characteristics
Modifying Volume Characteristics

4-9
4-9
4-10
4-10
4-11
4-12
4-13

4.3
4.3.1

USING DCL TO ACCESS FILES
Accessing Disk Files for Read and Write Operations
Reading Files from a Disk Volume• 4-14
Writing Files to a Disk Volume• 4-15
Writing Files from Disk Volumes to Magnetic Tape
Volumes • 4-15
Accessing Magnetic Tape Files for Read and Write
Operations
Locating ANSI-Labeled Magnetic Tape Files for READ or
WRITE Access • 4-17
Reading Files on Magnetic Tape Volumes •: 4-18
Writing to Files on Magnetic Tape Volumes • 4-19

4-13
4-14

4.3.1.1
4.3.1.2
4.3.1.3

4.3.2
4.3.2.1
4.3.2.2
4.3.2.3

4.4

USING COMMAND PROCEDURES TO ACCESS FOREIGN
VOLUMES

CHAPTER 5 TRANSFERRING INFORMATION
5.1

5.2
5.2.1
5.2.2

4-16

4-:20

5-1

TRANSFERRING INFORMATION WITHIN AND ACROSS
OPERATING SYSTEMS

5-1

USING THE COPY COMMAND TO TRANSFER
INFORMATION
Copying Files from Disk Volumes
Copying Files from Magnetic Tape Volumes

5-1
5-2
5-3
vii

Contents

5.2.2.1

Continuing the Copy Command at End-of-Tape • 5-4

5.2.3

Copying Files to and from Non-File-Structured Volumes
Copying Files to a Non-File-Structured Volume• 5-6
Copying Files from a Non-File-Structured Volume• 5-7

5.2.3.1
5.2.3.2
5.3

5.4
5.4.1
5.4.2
5.5
5.5.1
5.5.2

USING THE CONVERT UTILITY TO TRANSFER
INFORMATION

5-8

USING THE EXCHANGE UTILITY TO TRANSFER
INFORMATION
Invoking and Terminating the Exchange Utility
Using EXCHANGE at DCL Command Level

5-10
5-11
5-11

USING COMMAND PROCEDURES TO TRANSFER
INFORMATION
Using a Command Procedure to Copy Files
Using a Command Procedure to Exchange Information

5-12
5-12
5-13

APPENDIX A VMS DISK FILES AND VOLUMES
A.1
A.1.1
A.1.2
A.1.3
A.1.4
A.1.5
A.1.6
A.1.7
A.1.8
A.1.9
A.1.10

FILES-11 DISK STRUCTURE
Index File
Storage Bit Map File
Bad Block File
Master File Directory
Core Image File
Volume Set List File
Continuation File
Backup Log File
Pending Bad Block Log File
Files-11 On-Disk Structure Level 1 Versus Structure
Level 2

APPENDIX B VMS ANSI-LABELED MAGNETIC TAPE

viii

5-6

A-1
A-1
A-1
A-2
A-2
A-2
A-3
A-3
A-3
A-3
A-3
A-3

B-1

B.1

LOGICAL FORMAT OF ANSI-LABELED VOLUMES

B-1

B.2

VMS MAGNETIC TAPE ANCILLARY CONTROL PROCESS
(MTAACP)

B-1

Contents

B.3.1
B.3.2
B.3.3

BASIC COMPONENTS OF THE VMS ANSI-LABELED
FORMAT
Beginning-of-Tape and End-of-Tape Markers
Tape Marks
Labels

B-1
B-2
B-3
B-3

B.4
B.4.1
B.4.2
B.4.3
B.4.4

VOLUME AND FILE CONFIGURATIONS
Single-File/Single-Volume Configuration
Single-File/Multivolume Configuration
Multifile/Single-Volume Configuration
M ultifile/M ultivolume Configuration

B-3
B--4
B-5
B-5
8-7

B.5
B.5.1
B.5.1.1
B.5.1.2
B.5.1.3
B.5.1.4
B.5.2

VOLUME LABELS
VOL1 Label
Volume Identifier Field • B-9
Accessibility Field • B-9
Implementation Identifier Field • B-9
Owner Identifier Field • B-9
VOL2 Label

B-8
B-9

B.6
B.6.1
B.6.1.1
B.6.1.2
B.6.1.3
B.6.1.4

B-10
B-10

B.6.1.5
B.6.1.6
B.6.1.7
B.6.2
B.6.2.1
B.6.2.2
B.6.2.3
B.6.2.4
B.6.2.5
B.6.3
B.6.4

HEADER LABELS
HDR1 Label
File Identifier Field • B-10
File-Set Identifier Field • B-1 2
File Section Number and File Sequence Number Fields• B-12
Generation Number and Generation
Version-Number Fields• B-12
Creation Date and Expiration Date Fields • B-1 2
Accessibility Field • B-13
Implementation Identifier Field • B-13
HDR2 Label
Record Format Field • B-13
Block Length Field • B-14
Record Length Field • B-1 5
Implementation-Dependent Field• B-15
Buffer-Offset Length Field • B-1 5
HDR3 Label
HDR4 Label

B.7

TRAILER LABELS

B-16

B.3

B-9

B-13

B-16
B-16

Contents

INDEX

FIGURES
1-1
1-2
1-3
1-4
2-1
B-1
B-2
B-3
B-4
B-5
B-6
B-7

File Extents
Files-11 On-Disk Structure Hierarchy
Tracks and Cylinders
lnterrecord Gaps
Illustrating User Categories with a UIC of [100, 100]
Basic Layout of a VMS ANSI-Labeled Volume
Single-File/Single-Volume Configuration
Single-File/Multivolume Configuration
Multifile/Single-Volume Configuration
Multifile/Multivolume Configuration
Blocked Fixed-Length Records
Variable-Length Records

1-3
1-4
1-5
1-8
2-2
B-2
B-5
B-6
B-7
B-8
B-14
B-14

VMS Reserved Files
Labels and Components Supported by VMS

A-1
B-4

TABLES
A-1
B-1

Preface
The Guide to VMS Files and Devices describes some of the routine tasks that
general users perform on files and devices.

Intended Audience
This guide is intended for all general users.
The Guide to VMS Files and Devices is not a guide for system managers; it
is designed primarily for the private user. System managers should refer
to Introduction to VMS System Management and Guide to Setting Up a VMS

System.
If you are a novice user, you can use this guide as a stepping stone to a
basic understanding of file operations on disk and magnetic tape devices.
Experienced users unfamiliar with DIGITAL software can use it to gain
familiarity with DIGITAL terms and techniques. Experienced DIGITAL users
should find the guide useful because it describes in detail most of the disk
and magnetic tape operations routinely performed on the VMS operating
system.

Document Structure
The chapters in this guide contain the following information:
•

Chapter 1 describes basic file and magnetic tape device concepts.

•

Chapter 2 describes the protection schemes that apply to file and device
media.

•

Chapters 3-5 describe tasks frequently performed on private disk and
tape media. These chapters include examples of command procedures
designed to simplify the use of routine file and device operations.

•

Appendix A describes the Files-11 On-Disk Structure (ODS-2) for VMS
disk files and volumes.

•

Appendix B describes formats for VMS magnetic tape volumes and files.

Associated Documents
The tasks described in this guide employ various VMS utilities and DIGITAL
Command Language (DCL) commands. Detailed descriptions of the utilities
and commands are provided in the VMS utilities volumes and in the VMS
DCL Dictionary.

Your specific operations guide provides instructions for procedures used in
system installation.
The Guide to Setting Up a VMS System provides task-oriented instructions
for maintaining public files and volumes; these instructions include steps for
bootstrapping and running standalone BACKUP.
The VMS Local Area VAXcluster Manual provides information for maintaining
public files and volumes in a VAXcluster environment.
xi

Preface

The Guide to VMS System Security describes security features available through
the VMS operating system; see this guide for more information on data
protection.
The VAX Volume Shadowing Manual (not part of the VMS document set)
describes how to mount, dismount, and maintain volumes using the volume
shadowing option.

Conventions
Convention

Meaning
In examples, a key name (usually abbreviated)
shown within a box indicates that you press
a key on the keyboard; in text, a key name is
not enclosed in a box. In this example, the key
is the RETURN key. (Note that the RETURN
key is not usually shown in syntax statements
or in all examples; however, assume that you
must press the RETURN key after entering a
command or responding to a prompt.)

xii

CTRL/C

A key combination, shown in uppercase with a
slash separating two key names, indicates that
you hold down the first key while you press the
second key. For example, the key combination
CTRL/C indicates that you hold down the key
labeled CTRL while you press the key labeled C.
In examples, a key combination is enclosed in a
box.

$SHOW TIME
05-JUN-1988 11 :55:22

In examples, system output (what the system
displays) is shown in black. User input (what
you enter) is shown in red.

$ TYPE MYFILE.DAT

In examples, a vertical series of periods, or
ellipsis, means either that not all the data that
the system would display in response to a
command is shown or that not all the data a
user would enter is shown.

input-file, ...

In examples, a horizontal ellipsis indicates
that additional parameters, values, or other
information can be entered, that preceding
items can be repeated one or more times, or
that optional arguments in a statement have
been omitted.

[logical-name]

Brackets indicate that the enclosed item is
optional. (Brackets are not, however, optional
in the syntax of a directory name in a file
specification or in the syntax of a substring
specification in an assignment statement.)

quotation marks
apostrophes

The term quotation marks is used to refer
to double quotation marks ( n ) • The term
apostrophe ( · ) is used to refer to a single
quotation mark.

Summary of New and Changed Features
The Guide to VMS Files and Devices contains much of the same information
as the Version 4.4 Guide to VAX/VMS Disk and Magnetic Tape Operations.
The title and content have been modified to shift the focus to a more general
user-oriented style.
Enhanced DCL Commands

The following DCL commands have been enhanced for VMS Version 5.0:
•

ANALYZE/RMS_FILE/STATISTICS displays RMS file characteristics
information for determining:
Whether journaling is enabled
The global buffer count
Whether file monitoring is enabled

•

DIRECTORY /FULL displays whether journaling is enabled.

•

SHOW DEVICES displays changes to system output.

•

SHOW MAGTAPE displays change to odd parity line format.

xiii

Introduction to Files and Devices

This chapter provides an introduction to storage media and describes basic
file and device concepts. It also discusses the importance of identifying
routine operations performed on files and devices and the advantages of
using command procedures to execute them.

1 .1

The History of File Storage Media
As technology has progressed, so has the volume of information that must be
saved. Business and industrial concerns, for instance, have compiled many
types of data files about a wide range of subjects. For many years, all these
data files were stored on paper in desk drawers and filing cabinets. But, as
these paper files grew, it often took longer to locate the needed data than
to create it in the first place. Storing all of a company's data files on paper
became impractical.
As the need for saving data increased, the need also arose for a better
medium for storing and retrieving data quickly, reliably, and economically.
The computer and computerized filing systems provide such storage media.
At first, computerized files consisted of collections of punched cards, which
provide a means of grouping related pieces of information. This information
might represent, for example, a business event such as a purchase or sale of
office furniture. Or, in the engineering environment, the information could
represent variable equations and data constants related to stress analysis.
This information, grouped on a single card, represents a record of that event.
Records of similar events, grouped together, constitute a file.
As a storage medium, cards have certain advantages. They are easy to add,
delete, or rearrange. However, cards become worn, require physical handling,
and are bulky. Cards are also relatively slow to process because they allow
only sequential access. Sequential access means that the search for a record
starts at the beginning of the file and proceeds in order through each record.
At times, when the needed record (or group of records) is near the end of the
file, the search wastes computer processing time.
The introduction of magnetic tape as a storage medium eliminated some of
the disadvantages of cards. Magnetic tape provides both a storage medium
and a means for input/output (1/0), and its uses have grown along with the
needs of the user. Magnetic tape offers virtually unlimited storage. It requires
much less storage space than a card file with a comparable amount of data.
However, magnetic tape is limited as a storage medium because, like a card
file, it allows only sequential access.
In contrast to magnetic tape, disk storage allows direct file access. Direct
access means that the computer can locate the desired record without first
searching the records that precede it in the file. The time needed to access the
record is independent of the record's location in the file.

1-1

Introduction to Files and Devices
1 .2 Basic Device Concepts

1 .2

Basic Device Concepts
This section describes basic disk and magnetic tape device concepts for VMS
systems.

1.2.1

Disk Concepts
VMS files reside on Files-11 On-Disk Structure volumes. The term Files-11
On-Disk Structure refers to the logical structure given to the disk; namely,
a hierarchical organization of files, their data, and the directories needed to
gain access to them. The VMS file system implements the disk structure and
provides access control to the files located on the disk. This section describes
the Files-11 On-Disk Structure levels and defines the terminology related to
it. (The term Files-11 used alone always refers to File-11 On-Disk Structure
levels.)
The smallest addressable unit of information on a disk is a block. Files-11
On-Disk Structures define a block to consist of 512 8-bit bytes. Blocks can be
treated as units for transfer between a Files-11 disk volume and memory.
Blocks are logically grouped into clusters, which are the basic unit by which
disk space is allocated. The system manager or operator determines the
number of blocks in a cluster when a given disk, known as a volume, is
first prepared for use (initialized). Cluster sizes from 1 to 65,535 blocks are
allowed, but the smaller cluster sizes in the range are more practical. In
general, a disk with a relatively small number of blocks is given a smaller
cluster size, while larger disks are given larger cluster sizes to minimize the
overhead for disk space allocation.
Contiguous clusters allocated to a particular file have been given the name
extent. An extent can contain all or part of a file. If enough contiguous area is
available on the disk, the entire file is allocated as a single extent. Sometimes,
however, not enough contiguous area is available to contain the entire file,
or, when you create a file initially, you may not wish to reserve the entire
required amount of space. When the file is eventually extended, it is unlikely
that the adjacent clusters will still be unallocated. If the adjacent clusters are
already allocated to another file, the extension will not occur contiguously.
Whether the clusters are contiguous or not, the file is divided into two or
more parts, and each part is an extent. Thus, a file can consist of multiple
extents located in separate areas on the disk, as shown in Figure 1-1. Note
that the file extensions are done automatically.

1-2

Introduction to Files and Devices
1 .2 Basic Device Concepts

Figure 1-1

File Extents
Single extent for file A

ZK-738-82

1-3

Introduction to Files and Devices
1 .2 Basic Device Concepts

Figure 1-2 shows the hierarchy of blocks, clusters, extents, and files in the
Files-11 On-Disk Structure.
Figure 1-2

Files-11 On-Disk Structure Hierarchy

File

Extent3

You can exercise as little or as much control as you want over the allocation
of space on a Files-11 disk file. For example, you can specify the number
of blocks to be allocated and even give the exact location for the blocks on
the volume. On the other hand, you can allow VMS Record Management
Services (RMS) to handle all disk space allocation details automatically.

If you want, you can specify the size of the initial space allocation and the
size to be used by VMS RMS each time the file is extended. If you find
that a file needs less space than is allocated to it, you can specify that the
unused clusters are to be deallocated from the file. These clusters will then be
available for allocation to other files on the volume.
When a large amount of file storage space is needed, you can combine several
Files-11 volumes into what is called a volume set. A volume set, although
composed of several physical volumes, has the appearance of one large
volume. The different extents of a file can be located on different volumes in
the volume set. In general, you need not specify a particular volume in the
set to locate a file or create a new one, although it is possible (and sometimes
desirable for performance reasons) to specify a particular volume to be used
for a certain allocation request.
The smallest unit discernible to the Files-11 structure is the sector; for most
Files-11 disks, a sector is equivalent to a block, which is 512 bytes. Other
basic terms related to disks are track and cylinder. A track is the collection of
sectors (or blocks on Files-11 structures) at a single radius on one recording
surface of a disk. It is accessible to a given read/write head position on
the disk device. A cylinder consists of all tracks at the same radius on all
recording surfaces of a disk.
Because access to any of the blocks in a given cylinder does not require any
movement of the disk's read/write heads, it is generally advantageous to keep
related data blocks in the same cylinder. For this reason, when choosing a
cluster size for a large-capacity disk, a system manager often selects a cluster
size that divides evenly into the cylinder size.

1-4

Introduction to Files and Devices
1.2 Basic Device Concepts

Figure 1-3 Tracks and Cylinders

r---------1

I A track is comprised of
I the area at a single radius I
on one recording surface.
1
L _ _ _ _ _ _ _ _ _J1

r---------,I

I A cylinder consists of

these tracks in the same

I radius on all the recording I
~~~s~- - - __ .J

Recording occurs on both
surfaces of each platter. The
extreme top and bottom
surfaces of some disk models
are not used for recording.

ZK-740-82

Figure 1-3 is a graphic representation of tracks and cylinders.
The remainder of this section contains a brief explanation of some basic
elements of the Files-11 structure.
A Files-11 structure resides on a volume, which is a physical medium such
as a disk pack. A Files-11 volume is an ordered set of 512-byte blocks. The
blocks are numbered consecutively from 0 to n-1; the value of n-1 is the
size of the disk in blocks.
Each Files-11 volume has an index file, which is created when the volume
is initialized. (You cannot use a disk as a Files-11 disk until it has been
initialized with the INITIALIZE command.) The index file contains the
following information:
•

Bootstrap block

•

Home block

•

File headers

1-5

Introduction to Files and Devices
11 •'., D--:m;;ia~H\6

n-··=-1"-----.£.UCVllWC \,,Ull\,;t:fJU:i

The bootstrap block contains the bootstrap program and is physically the first
block on the volume. All Files-11 volumes have an area for this bootstrap
block even if the operating system does not require a bootstrap block. If the
volume is not the operating system volume, the bootstrap block area contains
a program other than the bootstrap program. If an attempt is made to boot
a nonsystem disk, this program displays a message on the system console
indicating that the volume is not the operating system volume.
The home block is normally the next block after the bootstrap block; it
identifies the disk as a Files-11 volume. If for some reason the home block
cannot be read (physically unusable), an alternative block will be selected for
use as the home block. This block provides specific information about the
volume and default values for files on the volume. Among the items in the
home block are the following:
•

The volume name

•

Information to locate the remainder of the index file

•

The maximum number of files that can be present on the volume at any
one time

•

The user identification code (UIC) of the owner of the volume

•

Volume protection information (specifies which users can read or write
the entire volume)

Files-11 volumes contain several copies of the home block to ensure against
accidental destruction of this information and the consequent loss of access to
files on the volume.
The bulk of the index file consists of file headers; each file header describes
one file on the volume. File headers contain information such as the owner
UIC, protection, creation date and time, and Access Control Lists (ACLs).
Most important, the file header contains a list of extents that make up the
file, describing where the file is logically located on the volume. If a file has a
large number of extents, multiple file headers may be used to describe them.
A file identifier number is associated with each file header.
When you create a file, you normally specify a file name to VMS RMS, which
assigns this name to the file on a Files-11 volume. RMS places the file name
and file identifier associated with the newly created file in a directory, which
contains an entry defining the location for each file. When you access the file,
you supply the file name, which supplies a path to the file identifier through
the directory entry. The file identifier, in turn, points to the location of the file
header, which contains a listing of the extent or extents that locate the actual
data.

1.2.2

Magnetic Tape Concepts
The VMS file storage system for magnetic tapes is based on the standard
magnetic tape structure as defined by the American National Standard
X3.27-1978 (referred to as the ANSI standard throughout this manual) and
also supports the ISO 1001-1979 standard.
Magnetic tape data is organized sequentially; the data records and files are
organized in the order in which they are written.

1-6

Introduction to Files and Devices
1 .2 Basic Device Concepts

On VMS systems, characters of data on magnetic tape are most commonly
measured in bits per inch (bpi). This measurement is called density. (The
ANSI standard uses characters per inch (CPI), which is equivalent to the bpi
convention used by VMS.) A 1600-bpi tape can accommodate 1600 characters
of data, using an inch of tape.
Even though a magnetic tape may have a density of 1600 bpi, there are
not always 1600 characters on every inch of tape because of the interrecord
gap (IRG). The IRG is an interval of blank space between data records; it is
created automatically when records are written to the magnetic tape. The IRG
is a breakpoint on the magnetic tape, which allows the magnetic tape unit to
decelerate and stop, if necessary, after a record operation and then accelerate
to working speed for the next record operation.
Each IRG is approximately 0.6 inch in length (this length varies with the type
of tape drive). Writing an SO-character record at 1600 bpi requires 0.05 inch
of space. Therefore, the IRG requires 12 times more space than the data,
wasting valuable storage space. RMS can reduce the size of this wasted space
by using record blocking. This technique groups individual records into a
block and places the IRG after the block rather than after each record.
Note that a block on magnetic tape is different from a block on disk. On disk,
a block is fixed at a size of 512 bytes; on magnetic tape, the size of a block is
determined by the user. However, record blocking requires more buffer space
to be allocated for your program, which increases RMS memory requirements.
The greater the number of records in a block, the greater the buffer size
requirements. You must determine the point at which the benefits of record
blocking cease. This determination should be based on the configuration of
your computer system and your authorized environment.
Figure 1-4 shows how space can be saved by record blocking. Assume that a
1600-bpi magnetic tape contains 10 records that are not grouped into a block.
Each record is 160 characters long (0.1 inch at 1600 bpi) with a 0.6 inch IRG
after each record. This uses 7 inches of tape. However, placing the same 10
records into one block uses only 1.6 inches of tape (1 inch for the data records
and 0.6-inch for the IRG).
Record blocking also increases the efficiency of the flow of data into the
computer. For example, ten unblocked records require ten separate physical
transfers, while ten records placed into a single block require only one
physical transfer. Moreover, a shorter length of magnetic tape is traversed for
the same amount of data; thus, the operation is completed in less time.
Data on magnetic tape is also organized into files. When you create a file
on magnetic tape, the magnetic tape file system writes a set of header labels
on the tape immediately preceding the data blocks. These labels contain
information such as the user-supplied file name, creation date, and expiration
date. Additional labels, called trailer labels, are also written following the file.
To access a file on magnetic tape by the file name, the file system searches
the tape for the header label set that contains the specified file name.
When the data blocks of a file or related files do not physically fit on one
volume (a reel of magnetic tape), the file is continued on another volume.
This is a multivolume file. The volumes in a multivolume file constitute a
volume set. When access is made to a file on a volume set, all volumes in the
set are accessible.

1-7

Introduction to Files and Devices
1.3 Using Command Procedures to Perform Routine File and
Device Operations

Figure 1-4 lnterrecord Gaps
WITHOUT RECORD BLOCKING
Record

Record

1.:.::1.::1;_:':1;_:\:'··.:1

Record

·~

IR G

.i::i.:::i::·.'::i::·.'..
:i.::\

I RG

:i\.:..\·':t'.:.:

1_:1::
..

Record

! i
I RG

I
11111111

Record

,,
IRG

Record

I I
IRG

Record

IRG

WITH RECORD BLOCKING

Al I 10 records

, , ,. .____
_
,

-1RGI
ZK-741-82

1.3

Using Command Procedures to Perform Routine File and Device
Operations
Many of the operations that you perform on disk and magnetic tape media
are routine in nature. Therefore, you will find it worthwhile to take the time
to identify those tasks that you routinely perform at your particular site. Once
you have isolated those tasks, you can design command procedures to assist
you in performing them.
If you are a system manager or an operator, for example, you must frequently
perform data integrity tasks such as backing up media. You could enter
all of the commands, parameters, and qualifiers required to back up your
media each time that you perform the backup operation, or you can write a
single command procedure (containing that set of commands, qualifiers, and
parameters) that, when executed, would also perform the backup operation.

In order to familiarize yourself with the syntax used to design and execute
command procedures, see the Guide to Using VMS Command Procedures.

1-8

File and Device Protection

The VMS operating system provides various types of protection. This chapter
focuses on data, file, and device protection for VMS systems.

2. 1

Data Protection
The VMS operating system protects data on disk and magnetic tape volumes
to ensure against accidental or unauthorized access. The term volume refers to
the entity that exists when a medium is mounted on a device. For example,
disk packs and reels of tape are called volumes when they are mounted on
disk and magnetic tape drives.
VMS systems support the protection of data on disk and magnetic tape media
at the volume and file levels. At the volume level, the system provides
protection for both disks and tapes. At the file level, the system provides
protection for individual disk files, directory files that reside on disk volumes,
and tape files. However, distinct file-level protection for magnetic tape files is
limited to one special case, described in Section 2.2.2.4.
In addition to protecting the data on mounted volumes, the system also
provides device-level protection. For more information on setting device
protection characteristics, see the descriptions of the DCL commands
INITIALIZE, MOUNT, and SET VOLUME in the VMS DCL Dictionary.
On VMS, data residing on disk and tape volumes can be protected by one or
more of the following:

2.1.1

•

User identification codes (UICs)

•

Access control lists (ACLs)

•

ANSI-standard accessibility (magnetic tape only)

User Identification Code (UIC)-Based Protection
User Identification Code (UIC)-based protection is supported for disk
and magnetic tape volumes and for individual files on disk volumes,
including directories. UIC-based protection is determined by an owner's
user identification code and a protection code. The owner UIC is normally
the UIC of the user who created the file or volume. The protection code
indicates who is allowed access and for what purposes.
UIC formats can contain alphanumeric characters or they can consist entirely
of octal numbers. For example, [VMS,USER] and [360,030] are both legitimate
UIC formats.
When a user attempts to access a file or volume, the user's UIC is compared
against the owner UIC of the file or volume. Depending on the relationship
of the UICs, the user falls into one or more of the following categories:
•

SYSTEM - All users who have system privilege (SYSPRV) or low group
numbers, usually from 1 through 10 (octal). However, the exact range
of system group numbers is determined by the system manager when

2-1

File and Device Protection
2. 1 Data Protection
the system is generated and may range as high as 37776 (octal). These
group numbers are generally for system managers, system programmers,
and operators. In addition, the SYSTEM protection field is used for those
users with the user privilege GRPPRV, whose UIC group matches the
group of the file or volume owner UIC.
•

OWNER - The user with the same UIC as the person who created, and
therefore owns, the volume or file

•

GROUP - All users, including the owner, who have the same group
number in their UICs as the owner of the file

•

WORLD - All users including those in the first three categories

Note: SYSTEM and OWNER categories always have access to magnetic tape
volumes, except as noted in Section 2.1.3.
Figure 2-1 illustrates the relationships of these categories to each other.
Figure 2-1

Illustrating User Categories with a UIC of [100, 100]

WORLD
(All UICs)

g = Group Number
m = Member Number

NOTE: THE SYSTEM MANAGER CAN EXTEND THE SYSTEM GROUP NUMBER LIMIT TO 37776 8
ZK-778-82

Each user category is allowed or denied five types of access:

2-2

•

READ

•

WRITE

•

EXECUTE

•

DELETE

•

CONTROL

File and Device Protection
2. 1 Data Protection

The meaning of each access type depends on the object to which it is applied
(disk or magnetic tape volume, file, or directory). Section 2.2.1 describes how
these types of access apply to disk and magnetic tape volumes; Section 2.2.2
describes how the access types apply to files and directories.
Note that CONTROL access is not explicitly set with the SET PROTECTION
command. CONTROL access to a file is a function of ownership and
privilege; therefore, it is never granted to the GROUP and WORLD categories
of users, but is always granted to SYSTEM and OWNER.
You can bypass all VIC-based protection checks if you have the BYPASS user
privilege. To bypass all protection checks and gain READ and CONTROL
access to a disk file, you need READALL user privilege. For magnetic tapes,
you can bypass VIC-based protection checks if you have VOLPRO (volume
protection override) privilege.
For information on how to set UIC-based protection, see the discussion of
protection codes in the VMS DCL Concepts Manual.

2.1.2

Access Control List (ACL)-Based Protection
An access control list (ACL) is primarily a list of entries that grant or deny
access to a particular system resource, such as a disk file or a directory. Each
access control list consists of one or more entries known as access control list
entries (ACEs).
ACLs offer you the chance to "fine tune" the action taken when access to
a file is sought. You can opt to provide an ACL on any disk file to permit
as much or as little access as is desirable in each case. In providing a more
detailed definition of who is allowed a particular kind of access, ACLs can
enhance the security of disk files. Note, however, that "fine tuning" is done at
the expense of performance; the larger the ACLs are, the more time they take
to process.
ACL-based protection is supported for files and directories on disk volumes
only. ACL protection is not supported for files on magnetic tape volumes.
If a file does not have an associated ACL, the system uses VIC-based
protection to determine access as described in Section 2.1.1.
If a file has an associated ACL, the system uses the ACL to determine access
as follows:
•

If the ACL includes an identifier entry for a particular VIC, the ACL

specification takes precedence over your UIC-based protection. However,
SYSTEM and OWNER may still have access. For detailed information on
ACL protection, see the Guide to VMS System Security.
•

If the ACL does not include an identifier entry for your VIC (that is, does

not explicitly allow or refuse access), then the system uses UIC-based
protection to determine access.
If you have CONTROL access to a resource, you can define the access control

list using the DCL commands EDIT/ ACL, SET ACL and SET FILE/ ACL.
For more information on how to invoke, modify, and display ACLs, see the

VMS Access Control List Editor Manual or the Guide to VMS System Security.

2-3

File and Device Protection
2. 1 Data Protection

2.1.3

VMS ANSI-Labeled Magnetic Tape Accessibility Protection
The VMS magnetic tape file system supports accessibility protection based on
the ANSI and ISO standards. This protection scheme allows an installation
to use a routine that is designed to interpret the contents of the volume- and
header-label accessibility field. See the $MTACCESS system service in the
VMS System Services Reference Manual for more information on installation
routines.
When the installation routine is called to interpret a VOLl label supplied as
input, the routine must return one of the following values to the magnetic
tape file system:
•

User has no access to the volume or file

•

User has complete access to the volume or file

•

The output of any other VMS protection mechanism specified (for filelevel access, the protection defaults to whatever was specified for the
volume)

If the installation routine determines that you have no access to a volume or
file, then you will be denied access regardless of the volume protection set by
VMS. That is, no privilege granted to you by VMS can override that decision.
On the other hand, if the installation determines that you have complete
access to the file or volume, then you will be granted complete access even if
a VMS protection scheme denies you access to that file or volume.

When the installation routine is called to return the VOLl label or HDRl label
as output, the routine must return the character to write into the volume- or
file-label accessibility field.
If you do not design your own installation routine, the VMS operating system
provides a default routine for you, which works in the following way. The
default installation routine first checks the ANSI standard version of the label.
For magnetic tapes with a version number of 3 or less, the routine outputs
either an ASCII character space (full access without checking VMS protection)
or the character specified by the user. On input of these magnetic tapes, the
routine checks for a blank (full access without checking VMS protection) and,
if the field is not blank, returns the value that causes the file system to check
for explicit override of accessibility checking.

For magnetic tapes with a version number greater than 3, the routine outputs
either the character specified by the user or an ASCII 1 if no character was
specified. On input of these magnetic tapes, the routine checks for an ASCII
character space. If the field has an ASCII space, the user is given full access
and VMS protection is not checked. If the field contains an ASCII 1 and the
VMS protection has been specified, the VMS protection is checked.
If the field does not contain an ASCII space or an ASCII l, the routine returns
the value to the magnetic tape file system that forces the user to override the
accessibility checking and allows the magnetic tape file system to check VMS
protection.

When called to return a VOLl or HDRl label as output, the routine returns
the ASCII character 1 if a VMS protection characteristic has been specified for
the volume. If no VMS protection was specified, then the routine returns the
ASCII character space.

2-4

File and Device Protection
2. 1 Data Protection

When the installation routine is called to interpret a VOLl or HDRl label
supplied as input, the routine returns the value that causes the magnetic tape
file system to check the VMS protection under the following conditions:
•

If the routine finds an ASCII 1 in the accessibility field when a VMS

protection has been specified and the magnetic tape conforms to an ANSI
standard greater than Version 3
•

If the magnetic tape conforms to an ANSI standard greater than Version
3

•

An ASCII space for all other cases

For all other conditions, the routine provided by VMS returns the value to
the magnetic tape file system that causes the file system to check for explicit
override of accessibility processing.
For more information on how ANSI-standard accessibility protection applies
to files on magnetic tape volumes, see Section 2.2.2.4.

2.2

File Protection
This section discusses file protection at both the volume level and file level.

2.2.1

Volume-Level Protection
Disks and tapes can both be protected at the volume level. When you prepare
a disk or magnetic tape volume for private use, you can define the protection
you want applied.
Volume protection for a disk or magnetic tape volume is usually set when
the volume is mounted or initialized. If you do not explicitly specify the
protection for a particular disk volume, the system provides a default
protection for you.
To change the protection that has been set on a disk volume, use the DCL
command SET VOLUME as described in the VMS DCL Dictionary. For more
information on setting the volume protection when you mount a volume, see
the VMS Mount Utility Manual and the descriptions of the DCL command
INITIALIZE in the VMS DCL Dictionary.

2.2.1.1

Disk Volume Protection
Disk volume protection supports the following access types:

•

READ

•

WRITE

•

EXECUTE

•

DELETE

If you have READ access to a disk volume, you have the right to examine,

print, execute, or copy files from that volume.

2-5

File and Device Protection
2.2 Fiie Protection

If you have WRITE access to a disk volume, you have the right to modify
existing files on that volume. Unlike that of magnetic tape volumes, WRITE
access to a disk volume does not automatically imply READ access. That is,
it is possible to grant a user WRITE access to a disk volume without granting
that user READ access to the volume.

When applied at the volume (as opposed to the file) level, EXECUTE access
means that you have the right to create files or modify existing files. When
applied at the file level, EXECUTE access gives you the right to invoke
executable files (such as executable images and command procedures).
If you have DELETE access to a disk volume, you have the right to delete
files on the volume.

2.2.1.2

Protection of Disk Volumes
By default, no protection is applied to newly initialized disk volumes. You
can specify protection with the /PROTECTION qualifier of the INITIALIZE
command, and you can specify an ACL for a disk volume. The following
example specifies UIC-based protection for the disk volume ACCOUNTl:
$ INITIALIZE WORKDISK: ACCOUNT! _$

/PROTECTION=(S:RWED,O:RWED,G:R,W:R)

You can respecify the protection each time you mount the volume by using
the /PROTECTION qualifier of the MOUNT command. You must own the
volume or have VOLPRO privilege to change protection.
You can also limit access to a disk volume with the following qualifiers to the
INITIALIZE and MOUNT commands:
•

/SYSTEM - All processes have RWED access to the volume, but only
system processes (or processes with SYSNAM and SYSPRV privileges)
can create first-level directories. (The volume is owned by [l, l ].)

•

/GROUP - System, owner, and group processes have RWED access to
the volume. World users have no access.

•

/NOSHARE - System and owner processes have RWED access to the
volume. Group and world users have no access.

At initialization time, the above qualifiers override any protection mask
specified. At mount time, however, the protection mask overrides the
qualifiers. When mounting or dismounting a volume, you must have
GRPNAM privilege to specify /GROUP and SYSNAM privilege to specify
/SYSTEM.

2.2.1.3

Magnetic Tape Volume Protection
Unlike disk volume protection, only READ and WRITE access apply to
magnetic tape volume protection.
If you have READ access to a magnetic tape volume, you have the right to
examine, print, or copy files from the volume. If you have WRITE access to
a magnetic tape volume, you have the right to append or write files to the
volume.

For magnetic tape volumes, WRITE access implies READ access. Thus,
granting a category of users WRITE access to a magnetic tape volume
automatically permits them to have READ access to the volume also.

2-6

File and Device Protection
2. 2 File Protection

There are two ways to protect a magnetic tape volume on a VMS system. You
can protect a magnetic tape volume through the UIC-based protection scheme
supported by VMS software. This scheme is checked on VMS systems only
and will be ignored in any interchange with non-VMS systems. You can
also protect a magnetic tape volume by using the guidelines of the ANSI
standards. This protection scheme supports the protection of magnetic
tape volumes in environments where interchange exists between VMS and
non-VMS operating systems.

2.2.1.3.1

Protection for VMS Magnetic Tapes
The VMS magnetic tape file system provides two levels of protection. One
level is defined by the ANSI standard and is encoded in the ACCESSIBILITY
field of the first volume label written on the magnetic tape. The second level
is UIC-based and is defined by the VMS magnetic tape file system. This
protection is encoded in the second volume label written on the magnetic
tape.

2.2.1.3.2

Protection for Interchange Environments
Magnetic tape volume protection is also supported for interchange between
VMS and non-VMS operating systems. Protection is supported for
interchange between VMS and DIGITAL operating systems other than VMS
(such as RSX-1 lM and TOPS-20) as well as between VMS and non-DIGITAL
operating systems.

For magnetic tapes processed on any operating system that supports a version
of the ANSI standard later than Version 3, the accessibility information in
the first volume label is processed exactly as described above. Magnetic
tapes processed on operating systems other than VMS Version 4.0 or later
have their protection characteristics encoded in the first volume label of the
magnetic tape volume.
In order to process a magnetic tape created on a DIGITAL operating system
other than VMS, a user must have VOLPRO privilege and must explicitly
override the check on the protection. If the magnetic tape had been created
with a specified accessibility, then a user wishing to access that tape must
have the appropriate privilege and must explicitly override the check on
accessibility. If the magnetic tape volume had not been created with such a
protection scheme, then a user wishing to access that magnetic tape would be
granted READ and WRITE access to that magnetic tape volume.
The VMS magnetic tape file system allows you to specify values for the fields
in which other DIGITAL operating systems currently write their protection
information. Except under conditions described in the two previous sections,
VMS will not process this field. Thus, this field can be used to store the
protection values for another operating system without affecting the VMS
protection characteristics on that particular volume.

2-7

File and Device Protection
.,,. . L
.,,.
L

2.2.2

11:::1r
ue

n--"'--"'=-rlULC..,LIUI I

File-Level Protection
In addition to volume-level protection, the VMS operating system supports
protection at the file level for all files residing on disk volumes, including
directories. In certain cases, file-level protection is also supported for magnetic
tape files. For files residing on magnetic tape volumes, however, only one
special case (described in Section 2.2.2.4) exists in which distinct file-level
protection applies.
File-level protection is described as it applies to each of the following:

2.2.2.1

•

Disk file protection

•

Directory file protection

•

Magnetic tape file protection

File Protection
For the most part, file protection is transparent. The tools exist, however,
to adjust the protection of a file as you see fit. You must own the file; have
control access to the file; or have GRPPRV, SYSPRV, BYPASS, or READ ALL
privilege to set the protection or modify the ACL of a file.

Note: You cannot completely protect a file without applying at least the same
protection to the directory in which the file resides; see Section 2.2.2.3.1
for information on directory protection.

2.2.2.1.1

Default File Protection
A new file receives default UIC-based protection and the default access
control entries (ACEs), if any, of its parent directory. A renamed file's
protection is unchanged. A new version of an existing file receives the UICbased protection and ACL of the previous version. (Use the /PROTECTION
qualifier of the BACKUP, COPY, and CREATE commands to override the
default UIC-based protection.)

•

Default UIC protection - The operating system provides each process
with a default UIC-based protection of (S:RWED,O:RWED,G:RE,W). To
change the default protection, enter the SET PROTECTION command
with the /DEFAULT qualifier. For example, if you place the following
command in your login command procedure, you grant all processes read
and execute access to any files that you subsequently create:
$ SET PROTECTION = (S:RWED,O:RWED,G:RE,W:RE)/DEFAULT

(Remember that you must execute the login command procedure for this
command to execute.)
•

Default ACL protection - You can override default UIC protection for
specified directories or subdirectories by placing a default-protection
ACE in the ACL of the appropriate directory file. The default protection
specified in the ACE is applied to any new file created in the specified
directory or in any subdirectory of the directory. The following ACE,
which must be in the ACL of a directory file, specifies that the default
protection - for that directory and for the directory's subdirectories allows system and owner processes full access, group processes read and
execute access, and world users no access:
(DEFAULT_PROTECTION,S:RWED,O:RWED,G:RE,W:)

2-8

File and Device Protection
2.2 File Protection

To specify a default identifier ACE to be copied to the ACL of any file
subsequently created in the directory, specify the DEFAULT option in the
directory file's identifier ACL.

2.2.2.1.2

Explicit File Protection

You can explicitly specify UIC-based protection for a new file with the
/PROTECTION qualifier (valid with the BACKUP, COPY, RENAME, and
CREATE command), as demonstrated in the following command line:
$ CREATE MAST12.TXT/PROTECTION=(S:RWED,O:RWED,G,W)

You can change the UIC-based protection on an existing file with the SET
PROTECTION command, as follows:
$SET PROTECTION=(S:RWED,O:RWED,G,W) MAST12.TXT

After a file is created and you have created an ACL for the file, you can
modify the ACL and add as many ACEs to the ACL as you desire. The
protection specified by the ACL overrides the file's UIC protection.

2.2.2.2

Disk File Protection

Each file on a disk has its own protection code, which is distinct from the
protection that applies to the disk volume itself. For files residing on disk
volumes, the following access types are supported:
•

READ

•

WRITE

•

EXECUTE

•

DELETE

•

CONTROL

If you have READ access to a file or group of files on a disk volume, you
have the right to examine, print, or copy that file or group of files. READ
access automatically includes EXECUTE access to a specified file or group of
files on disk.
If you have WRITE access to a file or group of files on a disk volume, you
have the right to modify the file or group of files. As with disk volume
protection, it is possible to be granted WRITE access without having READ
access. This is not very useful, however, since opening a file for a write
operation implies READ access.
If you have EXECUTE access to a disk file or group of disk files, you have
the right to execute executable program images or DCL command procedures
contained in that file or group of files.
If you have DELETE access to a particular disk file or group of disk files, you
have the right to delete the file or group of files.
If you have CONTROL access to a particular disk file or group of disk files,
you have the right to change the characteristics of the file or group of files.

You can specify a protection code when you create or copy a file by using the
/PROTECTION qualifier, as in the following example:
$ COPY/PROTECTION=(SYSTEM:RW,OWNER:RWED,GROUP:RW,WORLD) ABC.DAT

2-9

File and Device Protection
2. 2 Fiie Protection

You can also change the protection for an existing file by using the SET
PROTECTION command. For example, enter the following:
$SET PROTECTION=(SYSTEM:RWE,OWNER:RWED,GROUP:RE,WORLD) ABC.DAT

This command gives the VMS operating system the following instructions
regarding the file ABC.DAT: SYSTEM has READ, WRITE, and EXECUTE
privileges; OWNER has READ, WRITE, EXECUTE, and DELETE privileges;
GROUP has READ and EXECUTE privileges only; and WORLD has no
access.
For SYSTEM and OWNER, CONTROL access is implied and unchangeable,
but not so for GROUP and WORLD.
If you do not define a protection code for a file when creating it, the system
applies a default protection. If a version of the file already exists, protection
is taken from the previous version. For a new file, protection is determined in
one of the two following ways:
•

If the directory where the file is to be catalogued has an associated access
control entry that specifies the DEFAULT_pROTECTION entry, then the
specified protection is used.

•

If the directory does not have the DEFAULT_pROTECTION entry, then
the default process protection is used. The default process protection is
established explicitly with the SET PROTECTION/DEFAULT command,
or by default when you log in.

Show the current default protection by entering the SHOW PROTECTION
command as follows:
$ SHOW PROTECTION
SYSTEM=RWED, OWNER=RWED, GROUP=RE, WORLD=NO ACCESS

This response is the system default protection. It indicates that SYSTEM and
OWNER have all types of access, members of the owner's group have READ
and EXECUTE access, and all other users (WORLD) have no access.
To determine the current protection associated with a specific file or files, use
the /PROTECTION qualifier with the DCL command DIRECTORY, as in the
following example:
$ DIRECTORY/PROTECTION MYFILE.REC
Directory DBA1: [CRAMER]
MYFILE.REC;5

(RWED,RWED,RW,R)

Total of 1 file.

You can change the default protection applied to files created during an
interactive session by using the SET PROTECTION/DEFAULT command.
The SET PROTECTION/DEFAULT command indicates that the protection
code you specify is to be applied to all files subsequently created during the
terminal session or batch job (providing that the files are not subject to other
sources of protection).
Note that, to completely protect a file, you must protect both the file itself
and the directory in which the file is listed. If you have files that must
be protected against unauthorized access, be sure to specify the proper
protection both for the directories in which the files are listed and for the files
themselves.

2-10

File and Device Protection
2. 2 File Protection

2.2.2.3

Directory File Protection

Each directory file has a protection associated with it. The directory protection
can override the protection of individual files within the directory. For
example, if a directory denies WORLD access, WORLD users cannot look up
even those files in the directory that permit WORLD access.
For directory file protection, the following access types are supported:
•

READ

•

WRITE

•

EXECUTE

•

DELETE

•

CONTROL

Having READ access to a file in a directory means that you have the right
to examine, print, or copy that file. If you have READ access to a directory
file, you can display the contents of the directory file with the DIRECTORY
command. For example, if you have access to the directory [JONES], you can
enter the following:
$ DIRECTORY [JONES]

This command generates a display of the files contained in the [JONES]
directory.
If you have READ access, you can access any file listed in the directory,
unless the protection on that file denies you access. If the protection applied

to the whole directory denies you READ access, then you cannot access even
those files in the directory that permit access to users in your group.
If you have WRITE access to a directory file, you have the right to modify or

write to that directory file. However, you must have both READ and WRITE
access to a directory in order to create files in that directory, to rename files in
that directory, or to perform any file operation that involves changes to that
directory file.
Note that EXECUTE access has a special meaning when applied to directories.
EXECUTE-only access to a directory file allows you access only to files that
you can identify by name. It also means that you can access files in the
directory that are not protected against users in your category, provided that
you do not perform an operation that modifies the directory file. However,
you cannot list all the entries in a directory by using wildcards.
For example, assume you have EXECUTE-only access to the [JONES]
directory, and you enter the following command:
$ DIRECTORY [JONES]

The system responds with an error message and does not list the files in the
[JONES] directory. However, if you know that the file DATAFILE.DAT resides
in the [JONES] directory, you can enter the following command:
$ TYPE [JONES]DATAFILE.DAT

This causes the system to display the contents of the file. Thus, EXECUTEonly access provides some, but not all, of the operations that READ access
provides.

2-11

File and Device Protection
2.2 File Protection

If you have DELETE access to a directory file, you have the right to delete that
directory file. You must remove all entries from a directory file before you can
delete it. When you create a directory file with the CREATE/DIRECTORY
command, you do not, by default, get DELETE access. If you want to be able
to delete a directory file, you must use the DCL command SET PROTECTION
to explicitly assign DELETE access to the OWNER category.
If you have CONTROL access to a directory file, you have the right to change
the characteristics of the directory file.

Remember that, to ensure that your disk files are adequately protected, you
must make certain they are properly protected at both the directory and
file levels. ACLs allow you to further control access to disk files. For more
information on ACLs, see the VMS Access Control List Editor Manual.

2.2.2.3.1

U IC Directory Protection
You cannot completely protect a file without applying at least the same
protection to the directory in which the file resides. For example, if you
deny a user all access to a file but allow that user READ access to the file's
directory, the user cannot access the contents of the file but can see that it
exists. Conversely, a user allowed access to a file and denied access to the
file's directory (or one of the parent directories) cannot see that the file exists.

Note: To protect sensitive files, the directory protection alone is not adequate.
You must also protect each individual file contained within the directory.
By default, top-level directories receive UIC-based protection
(S:RWE,O:RWE,G:RE,W:E) and no ACL. Subdirectories receive UIC-based
protection minus any DELETE access or default protection ACEs from the
parent directory.
To specify UIC-based protection explicitly when creating a directory, use
the /PROTECTION qualifier of the CREATE/DIRECTORY command. You
cannot specify an ACL for the directory until the directory is created. To
change the UIC-based protection of an existing directory, use the SET
PROTECTION command (apply this command to the directory file). To
specify or change the ACL of an existing directory, edit the directory file's
ACL (see Section 2.2.2.1.1).
You can limit but not prohibit directory access by specifying EXECUTE access
but not READ access. EXECUTE access on a directory permits you to examine
and read files that you know are contained in the directory (that is, you know
the file specifications) but prevents you from displaying a list of the files in
the directory.

2.2.2.4

Magnetic Tape File Protection
In general, the protection that applies to a magnetic tape volume also applies
to all the files on that volume. For VMS ANSI-labeled magnetic tapes,
however, distinct file-level protection is also supported. For VMS ANSIlabeled magnetic tapes, file-level protection can be determined by the contents
of the accessibility field, which is located in the first header label of each file.

Each time a VMS ANSI-labeled magnetic tape file is opened for processing,
the installation routine examines the contents of the accessibility field of that
file. Depending on the value returned by this routine, access to the file in
question will either be granted, denied, or defaulted to the VMS protection
scheme applied to the volume containing that file (see Section 2.1.3).

2-12

File and Device Protection
2.2 File Protection

2.2.2.5
Protection of Mail Files
Note: (Requires the Common Utilities Option.)

Mail files receive the protection (S:RW,O:RW,G, W). Files of type MAI created
with the Mail Utility EXTRACT /MAIL command receive the protection
(S:RW,O:RW,G, W).
2.2.2.6

2.3

Displays of Ownership and Protection
You can display ownership and protection information with the following
commands and qualifiers:
Command

Display

DIRECTORY/ ACL filespec

File's ACL

DIRECTORY /OWNER_UIC filespec

File's UIC

DIRECTORY /PROTECTION filespec

File's UIC-based protection

DIRECTORY /SECURITY

All of the above

DIRECTORY /FULL filespec

All of the above and more

SHOW ACL obj-name

Device, file, logical name table, or
global section's ACL

SHOW PROCESS

Process UIC

SHOW PROTECTION

Default file protection

SHOW DEVICES/FULL device-name

Device UIC and protection

Device Protection
In general, device protection controls the ability to allocate the device and is
specified by granting READ access in an ACL. To specify an ACL for a disk
device, use the SET ACL/OBJECT_TYPE=DEVICE command. For example,
to grant READ access to the disk device WORKDISK to a user with the
alphanumeric UIC [FRED], enter the following:
$ SET ACL/OBJECT_TYPE=DEVICE/ACL=(IDENTIFIER=[FRED] ,ACCESS=READ) _$

WORKDISK

Note that, when you mount an ACL for a disk device, the ACL is associated
with the device not with the disk volume. For example, if you mount a
disk device on WORKl and specify the preceding SET ACL/OBJECT_
TYPE=DEVICE command and then dismount the disk device, the ACL
protection remains on WORKl but not on the disk device.
The only protection that applies to a nonfile device is the ability to allocate it,
specified by READ access. By default, nonfile devices such as mailboxes are
unprotected. Interactive terminals are set up to provide complete access to
system users and no access to all other users. (Note that access here refers to
access via an application program. The device protection on a terminal does
not control who can log in on it.) You can change the protection of a nonfile
device through the use of ACLs or by changing the standard UIC

2-13

File and Device Protection
2.3 Device Protection

protection. Modify the ACL with the DCL command SET ACL/OBJECT_
TYPE=DEVICE. Modify the UIC protection with the DCL command SET
PROTECTION/DEVICE (requires OPER privilege). For example, the
following command allows users holding the PAYROLL identifier to have
READ access to TERMINAL3:
$ SET ACL/OBJECT_TYPE=DEVICE/ACL=(IDENTIFIER=PAYROLL,ACCESS=READ)_$

2-14

TERMINAL3

Preparing Volumes for Private Use

You can prepare private disk and magnetic tape volumes for routine
operations by using the DCL commands ALLOCATE, INITIALIZE, and
MOUNT. Each of these DCL commands is discussed in the sections that
follow.
If you are interested in setting up public volumes, see the description in the

Guide to Setting Up a VMS System.

3.1

Setting Up a Private Volume
Under some circumstances, it may be desirable to perform your work on a
device that cannot be accessed by unauthorized users. By creating a private
volume and mounting it on a device allocated exclusively to your process,
you can perform your work without fear of interference from other users.
To set up your private volume, perform the following steps:
1

Use the ALLOCATE command to assign a disk drive or magnetic tape
drive exclusively to your process.

Use the INITIALIZE command to format the volume and write an
identifying label on the volume.

Use the MOUNT command to make a volume, and the files or data it
contains, accessible to your process.

See the section dealing with the individual DCL command for a complete
description of each parameter and qualifier. Also see the DCL commands
ALLOCATE and INITIALIZE in the VMS DCL Dictionary, and for more
information on MOUNT, see the VMS Mount Utility Manual.

3.2

Allocating Disks and Magnetic Tape Drives to Your Process
Before you can begin processing files or data on a private volume, you must
first allocate a drive to your process. Use the DCL command ALLOCATE to
logically assign a disk drive or a magnetic tape drive to your process.
Whether you are allocating a disk drive or a magnetic tape drive, the format
for the ALLOCATE command is as follows:
ALLOCATE device-name(:] (logical-name]

Command Parameters
device-name[:]

Specifies the drive on which the volume will be loaded. The device name can
be a physical, generic, or logical name. A physical device name consists of a
device code, alphabetic controller designation, and a, unit number. A generic
device name consists only of the device code. A logical name must equate to
a physical or generic name. Use of the colon is optional but recommended by
DIGITAL.

3-1

Preparing Volumes for Private Use
3.2 Allocating Disks and Magnetic Tape Drives to Your Process

[logical-name]

Specifies an optional logical name to be associated with the specified disk or
magnetic tape drive.
The ALLOCATE command allocates only one device to a process. Except
for a list of generic device names, ALLOCATE does not accept lists of device
names in the command string. Although you can specify a list of generic
devices, the first available device will be the only one to be allocated. For
a list of available devices, refer to the Software Product Description (SPD)
supplied with your system software.
In the examples that follow, the first two show how to use the ALLOCATE
command to allocate disk drives, while the next three show how to allocate
magnetic tape drives.
Examples

$ ALLOCATE DM: DISK

In this example, the ALLOCATE command requests that the first available
RK06 or RK07 be assigned to your process. The logical name DISK is placed
in your process logical name table and assigned the name of the allocated
device. Other users are unable to access the device.
~

$ ALLOCATE DMB2 :
%DCL-I-ALLOC, _MARS$DMB2: allocated

In this example, the ALLOCATE command specifies a physical device named
DMB2, which requests the allocation of a specific RK06 or RK07 disk drive;
that is, unit 2 on controller B. The response from the ALLOCATE command
indicates that the device was successfully allocated.
If you want to allocate a particular type of device, use the /GENERIC qualifier
with the ALLOCATE command. For example, device DM could be an RK06
or RK07 disk. If you specifically want to allocate an RK07, use the /GENERIC
qualifier in the following way:
$ ALLOCATE/GENERIC RK07

MYDISK

In this case, the system allocates the first available RK07 device to your
process. For further discussion of the /GENERIC qualifier as well as all of
the qualifiers applicable to the ALLOCATE command, see the VMS DCL

Dictionary.

$ ALLOCATE MTA1:
%DCL-I-ALLOC, _MARS$MTA1: allocated

In this example, the ALLOCATE command specifies a physical device named
MTAl.
The operating system informs you that MTAl has been allocated.

3-2

Preparing Volumes for Private Use
3.2 Allocating Disks and Magnetic Tape Drives to Your Process

$ ALLOCATE MF , MT , MS DRIVE
%DCL-I-ALLOC, _MARS$MTAO: allocated

In this example, the ALLOCATE command specifies a list of generic device
names. At a minimum, a generic device name consists of the device code; a
controller designation is optional. Only one of the specified generic devices
is allocated. Each element in the list must represent a unique generic device
type.
The VMS operating system informs you that drive MTAO has been allocated.
Although it is not indicated in the message, the system also assigns the logical
name DRIVE to the drive MTAO.
~

$ ALLOCATE DRIVE1: 01
%DCL-I-ALLOC, _MARS$DBA3: allocated

In this example, the ALLOCATE command specifies a logical name, DRIVEl,
as the device name and assigns a new logical name, Dl. (This example
assumes that DRIVEl has already been defined as the physical device DBA3.)
The VMS operating system informs you that DRIVEl has been allocated.
Although it is not indicated in the message, VMS also assigns the new logical
name Dl to the drive DRIVEL
If you want to allocate a specific type of magnetic tape device, use the
/GENERIC qualifier. For example, if you want to allocate a TU78 device
specifically, you would use the /GENERIC qualifier with the ALLOCATE
command, as follows:
$ ALLOCATE/GENERIC TU78

TAPE_TU78

In this case, the system would allocate the first available TU78 device to your
process. For a further discussion of the /GENERIC qualifier as well as all
of the qualifiers applicable to the ALLOCATE command, see the VMS DCL

Dictionary.

3.3

Initializing a Volume
Before you can write files or data to a disk or magnetic tape volume, the
volume must be initialized. You can use the DCL command INITIALIZE to
format and write a label to the volume.
The INITIALIZE command does the following:
•

Invalidates all existing data on the volume, if any, and creates a new file
structure

•

Writes a label on the volume to identify it

•

Defines the owner UIC and the protection for the volume

Whether you are initializing a disk or magnetic tape volume, the format for
the INITIALIZE command is as follows:
INITIALIZE device-name[:] volume-label

3-3

Preparing Volumes for Private Use
3.3 Initializing a Volume

Command Parameters
device-name[:]

Specifies the name of the device on which the volume is to be physically
mounted and then initialized. To prevent initializing another user's volume,
you should allocate a device before you initialize the volume. Prior allocation
is not required, however.
volume-label

Specifies the identification to be encoded on the volume. You can
specify up to 12 alphanumeric characters for a disk volume, or up to 6
alphanumeric characters for a magnetic tape volume. Alphabetic characters
are automatically changed to uppercase. The first character of a disk volumelabel specification must be alphanumeric.
There are some cases where you might be prevented from accessing and
initializing a particular volume. For example, if the volume that you want
to initialize previously contained data, the protection code may prevent
you from accessing and initializing that particular volume. In the case of a
magnetic tape volume, you may not be able to initialize the volume if the
first file on the volume has not reached its expiration date or if the volume
or file accessibility is such that the installation routine provided by the VMS
operating system does not allow you to access the volume.
If the volume is protected or if the expiration date on the first file has not
been reached and you are not the owner or a SYSTEM user, you must have
VOLPRO user privilege to override volume protection. If you do not have
VOLPRO privilege, you can ask the previous owner of the volume or another
user who does have READ /WRITE access (the system manager or operator,
for example) to initialize it for you. If the installation routine provided by the
VMS operating system (or by a user-designed installation routine) does not
allow you aq:ess, then consult your system manager.

When you give the volume to another user for initialization, you should
specify the following:
•

The label you want to have written on the volume

•

The protection code and owner UIC you want assigned to the volume

When you obtain a magnetic tape or disk volume, place identification on the
outside of the volume so that it can be easily identified.
The next two sections describe how to initialize disk and magnetic tape
volumes.

3.3.1

Initializing a Disk Volume
By default, the INITIALIZE command builds a Files-11 structure on your new
volume. The default format for disk volumes in the VMS operating system is
called the Files-11 On-Disk Structure Level 2. The INITIALIZE command can
also initialize disk volumes in the Files-11 On-Disk Structure Level 1 format.
You do not need special privileges to override logical protection on a blank
disk volume (that is, a volume that has never been written to) or on a disk
volume that is owned by your current UIC or by UIC [0,0]. In all other cases,
you must have the user privilege VOLPRO to initialize a disk volume.
The following examples include typical cases of initializing a disk.

3-4

Preparing Volumes for Private Use
3.3 Initializing a Volume

Examples

$ INITIALIZE DISK USER_DISK

In this example, the volume is given the label USER_DISK. DISK is the
logical name of the device on which it is mounted.
~

$ALLOCATE DJA2: TEMP
%DCL-I-ALLOC, _MARS$DJA2 allocated
$ INITIALIZE TEMP: BACKUP_FILE

This example shows how to initialize an RA60 volume. First, the drive is
allocated to ensure that no one else can access it. Then, when the volume is
physically loaded on the drive, the INITIALIZE command initializes it. Refer
to the Software Product Description (SPD) for a complete list of devices that
are available.

3.3.2

Initializing a Magnetic Tape Volume
Use the INITIALIZE command to initialize a magnetic tape volume. The
default format for magnetic tape volumes in the VMS operating system is
based on Level 3 of the ANSI and ISO standards for magnetic tape labels and
file structure for informational interchange).
Use the DCL command INITIALIZE to encode VMS ANSI-labeled format on
a magnetic tape volume. INITIALIZE writes labels to an empty file on the
magnetic tape volume in the following order:
1

A volume label

File-header labels with the file sequence number set to 0

Two tape marks framing an empty file (BOT and EQT)

Corresponding end-of-file labels (EOF)

A double tape mark, specifying logical end-of-volume

The following example describes how to initialize a magnetic tape volume:
$ INITIALIZE TAPE USER

In this example, the magnetic tape volume is given the label USER. TAPE is
the logical name of the device on which it is mounted.
Note that, if you use ANSI "a" characters (which are not alphanumeric) on
the volume label on magnetic tape, you must enclose the volume name in
quotation marks.

3-5

Preparing Volumes for Private Use
3.4 Mounting a Volume

3.4

Mounting a Volume
Before you can begin processing files or data on your private disk or magnetic
tape volume, make sure the volume is mounted. Use the DCL command
MOUNT to make a disk or magnetic tape volume and the files or data it
contains accessible to your process.
When you enter the MOUNT command, the system checks the following:
•

That the device has not been allocated by another user

•

That the device protection allows you to allocate the device

•

That a volume is physically loaded on the device specified

•

That the label on the volume matches the label specified

You can mount a single volume or a volume set. Binding volumes into a
volume set allows you to extend the space available for your files by adding
volumes to the set, rather than defining new volumes.
The procedures for creating and mounting disk volume sets and magnetic
tape volume sets (as opposed to single volumes) are described in the sections
that follow. Whether you are mounting a disk or a magnetic tape volume, the
format for entering the MOUNT command is as follows:
$MOUNT device-name[:][, ... ] [volume-label[, ... ]] [logical-name[:]]

Command Parameters
device-name[:][, ... ]
Specifies the physical device name or logical name of the device on which
the volume is to be mounted. If you specify more than one device name for
a disk or magnetic tape volume set, separate the device names with either
commas (,)or plus signs ( + ).
volume-label[, ... ]

Specifies the label on the volume. If you specify more than one volume label,
separate the labels with either commas or plus signs. The volumes must be in
the same volume set. For magnetic tape volumes, the labels must be specified
in ascending order according to relative volume number.
The volume-label parameter is not required when you mount a volume
with the /FOREIGN or /NOLABEL qualifier or when you specify
/OVERRIDE=IDENTIFICATION. To specify a logical name when you
enter either of these qualifiers, type any alphanumeric characters in the
volume-label parameter position.
logical-name[:]
Defines a 1 through 255 alphanumeric character string to be associated with
the device.
If you do not specify a logical name for a disk drive, the MOUNT command

assigns the default logical name DISK$volume-label to individual disk drives;
it assigns the default logical name DISK$volume-set-name to the device on
which the root volume of a disk volume set is mounted. Similarly, if you do
not specify a logical name for a magnetic tape drive, the MOUNT command
assigns only one logical name, TAPE$volume-label, to the first magnetic tape
device in the list. For a volume set, no logical name is assigned unless you
specify one.

3-6

Preparing Volumes for Private Use
3.4 Mounting a Volume

The MOUNT command places the name in the job logical name table,
unless you specify /GROUP or /SYSTEM. In the latter cases, it places the
logical names in the group or system logical name table. You should avoid
assigning a logical name that matches the file name of an executable image
in SYS$SYSTEM. Such an assignment will prohibit you from invoking that
image.
At many installations, operators perform the physical mounting (and
dismounting) of both system and private disk and magnetic tape volumes.
Since operators at such installations assist you in your MOUNT requests, you
do not need to include the /ASSIST qualifier with the MOUNT command.
For example, the following command notifies the operator of your mount
request and displays a message at your terminal:
$MOUNT DMA1: DISK VOL1
%MOUNT-I-OPRQST, PLEASE MOUNT DEVICE _MARS$DMA1:

After the device has been successfully mounted, you are notified with the
following message:
%MOUNT-I-MOUNTED, DISK mounted on _DMA1:

As an alternative to requesting a specific device, you might want to request a
device type. In the following example, MOUNT allocates an available device
of the specified type and requests operator assistance in mounting it:
$ MOUNT DB: USER_DISK DISK
%MOUNT-I-OPRQST, Please mount volume USER_DISK in device _NODE$DBAO:
%MOUNT-I-MOUNTED, USER_DISK
mounted on _NODE$DBAO:
%MOUNT-I-RQSTDON, operator request canceled - mount completed successfully

DISK is the logical name created when the RP06 disk unit is allocated. Since
the device is allocated to your process, no other user can access the volume.
Your access to USER_DISK is determined by the volume protection code and
the volume UIC.
Operator assist messages are sent to all operators enabled to receive TAPE
and DISK messages. Thus, if operator assistance is needed for mounting a
disk device, a message is sent to disk operators.
Any operator reply to a MOUNT request is written to SYS$0UTPUT to be
displayed on the user's terminal or written in a batch job log.
If no operator is available (operator is not enabled) to receive and respond to
a MOUNT request, a message is displayed to inform you of the situation.
A volume placed in the requested drive needs no additional operator
assistance. Note that you can specify the /NOASSIST qualifier to avoid
operator assistance.

The following sections provide examples of mounting volumes; however,
they do not all include operator assistance messages.

3-7

Preparing Volumes for Private Use
3.4 Mounting a Volume

3.4.1

Mounting a Disk Volume
Use the following procedure to allocate, initialize, and mount a disk volume:
$ALLOCATE DMA2: TEMP
%DCL-I-ALLOC, _MARS$DMA2: allocated
$ INITIALIZE TEMP: BACKUP_FILE
$MOUNT TEMP: BACKUP_FILE
%MOUNT-I-MOUNTED, BACKUP_FILE mounted on _DMA2:

If you want to mount a foreign disk volume (that is, one having a file
structure other than Files-11), use the /FOREIGN qualifier in conjunction
with the MOUNT command. The MOUNT /FOREIGN command makes the
contents of your volume available to the system but makes no assumptions
concerning its file structure. In the following case, assume that DISK is the
logical name assigned to the device at the time of disk allocation:
$ MOUNT/FOREIGN DISK
YoMOUNT-I-MOUNTED, BACKUP_FILE

mounted on DISK$DMA2:

Note that MOUNT reports a volume label even though the disk is mounted
as a foreign device. MOUNT reports the label because the disk has a Files11 structure; if a disk does not have a recognized file structure, no label is
reported.
You need the user privilege VOLPRO to mount a Files-11 structured disk
with the /FOREIGN qualifier, unless its owner UIC matches your own.
You must use the /FOREIGN qualifier if you want to use the VMS Bad
Block Locator Utility (BAD) to locate and record bad blocks on your disk
volume. BAD is useful for media preparation and is thus distinct from the
volume preparation tasks described in this chapter. To invoke BAD, use the
DCL command ANALYZE/MEDIA. For more information on BAD, see the
description in the VMS Bad Block Locator Utility Manual
In addition to the /FOREIGN qualifier, many other qualifiers are supported
for the MOUNT command. The /SYSTEM qualifier is described in the Guide
to Setting Up a VMS System. The /BIND qualifier is discussed in the next
section, which describes how to mount disk volume sets. For a complete list
of the qualifiers, see the DCL MOUNT command.

3.4.2

Mounting a Disk Volume Set
When you mount a disk volume set, the volume label specified in the list
must correspond to a device name in the same position in the device name
list.
Two or more disk volumes can be bound into a volume set. The first volume
in the set is called the root volume. Each volume in the set is identified by
a volume number relative to the root volume, which is always relative to
volume 1.
A disk volume set has a single directory structure. The master file directory
(MFD) for the entire volume set resides on the root volume, which is always
the first volume in the set.
When a disk volume set is on line and mounted, all files and directories in
the set can be accessed by specifying either of the following:
•

3-8

Device name of the device on which the root volume is mounted

Preparing Volumes for Private Use
3.4 Mounting a Volume

•

Logical name assigned to the volume set when it was mounted

Use the /BIND qualifier to create a disk volume set. When you use the
MOUNT command with the /BIND qualifier to create a disk volume set, the
/BIND qualifier identifies a volume set by assigning it a volume set name that
applies to all volumes in the set. It also identifies the root volume and creates
the directory structure for the volume.
When you create files on a volume set, the file system allocates space for the
files anywhere on the set, whereve~ the most space exists. When existing files
on any volume are extended, exte~sion occurs on the same volume, unless
the volume is physically full. You can add new volumes to a volume set
whenever additional space is need d.
For example, all disk volumes that are mounted on a daily basis can be bound
into a volume set. Since this set contains all user file directories, users do
not need to specify device names in file specifications to access files on any
volume in the volume set. In fact, the physical location of a file is of no
concern to users of the system.

Note: Do not bind your system disk into a volume set. Volume sets are not
supported by VMS software updates and optional product installation.
If certain system files move or extend to other volumes in the set, the
system may fail to boot.
No special privileges are required to use volume sets. However, you must
have WRITE access to the index file on all volumes you are attempting to
bind into a volume set; this usually means you also must have a system UIC,
have the user privilege SYSPRV, or be the owner of the volumes.
You can create a disk volume set from newly initialized volumes, or you can
create a volume set by extending an existing volume that already contains a
directory structure and files. You can also add volumes to an existing volume
set. The next three sections contain examples of how to create and mount
each type of disk volume set.

3.4.2.1

Creating a Disk Volume Set from New Volumes
The following steps show how to create a disk volume set from new disk
volumes. This example assumes there are no files or data on the volumes to
be bound.

Allocate the necessary devices and physically load the volumes.

Initialize each volume in the set by entering the following:
$ INITIALIZE DB1:
$ INITIALIZE DB2:
$ INITIALIZE DB3:

PAYVOL1
PAYVOL2
PAYVOL3

When you initialize volumes for a volume set, you can also use other
qualifiers with the INITIALIZE command to define the volume ownership
and protection. Protection and ownership information is obtained from
the root (first) volume. The protection and ownership of the other
volumes is ignored.
3

Enter the following MOUNT /BIND command to create the volume set:
$ MOUNT/BIND=MASTER_SET _$

DB1:

DB2:

DB3:

PAYVOL1

PAYVOL2, PAYVOL3

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Preparing Volumes for Private Use
3.4 Mounting a Volume

This MOUNT /BIND command defines the volume set name, MASTERSET, and defines the relative volume numbers of the volumes PAYVOLl,
PAYVOL2, and PAYVOL3.
A disk volume set name can have from 1 to 12 alphanumeric characters. The
volume set name must be different from all volume labels within the set, and
all labels in the set must be unique.
The order of the device names corresponds to the volume labels specified:
PAYVOLl must be physically loaded on DBl, PAYVOL2 on DB2, and
PAYVOL3 on DB3.
PAYVOLl, which is listed first in the list of labels, becomes the root volume
of the set. The master file directory (MFD) for PAYVOLl contains the
directory structure for the entire volume set.
Note that the MOUNT/BIND command creates the volume set and mounts
the volumes. When this command completes successfully, all volumes in the
set are ready for use - user file directories can be created.
The /BIND qualifier must be used only once to create the volume set. In
subsequent use, the volume set may be mounted with a single MOUNT
command. The following example illustrates the use of one MOUNT
command to mount a previously created volume set:
$MOUNT DB1,DB2,DB3 PAYVOL1,PAYVOL2,PAYVOL3

3.4.2.2

Creating a Disk Volume.Set from an Existing Volume

The following example shows how to create a disk volume set from an
existing volume, assuming that the volume USERFILES already contains a
directory structure and files and that the volume is currently located on the
device DMl:
$ DISMOUNT/NOUNLOAD DM1:
$ INITIALIZE DM2: USERFILES2
$ MOUNT/BIND=USERS _$ DM1:, DM2:
USERFILES. USERFILES2

The initial volume USERFILES must be specified first; it becomes the root
volume of the set. When you create a volume set from an existing volume,
you must specify that volume first because the file system must build on the
existing directory structure.
Note that, if you attempt to create a volume set from two or more volumes
that already contain files and data, the file system does not issue an error
message when you enter the MOUNT /BIND command. However, the
volumes are unusable as a volume set because the directory structures are not
properly bound.

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3.4 Mounting a Volume

3.4.2.3

Adding Volumes to a Disk Volume Set

This section describes how to add volumes to an existing volume set. The
following example assumes that the volume set named MASTER_SET is
on line and mounted and has volumes named PAYVOLl, PAYVOL2, and
PAYVOL3:
$ INITIALIZE DB4: PAYVOL4
$ MOUNT/BIND=MASTER_SET DB4: PAYVOL4

The MOUNT command binds the volume PAYVOL4 with the existing
volume set and makes the volume ready and available for use. Note that, if
the volume set MASTERJ AY was mounted with the /SYSTEM, /GROUP,
or /SHARE qualifier, the MOUNT/BIND command that adds a volume to
the set must also specify the appropriate qualifier.
When you add a volume to an existing set, the only volume in the set that
must be mounted is the root volume, relative volume 1. None of the other
volumes need be mounted.
You can also add a volume to a set at the same time you mount the set. The
following procedure assumes an existing volume set named MASTER-SET
with volumes named PAYVOLl, PAYVOL2, and PAYVOL3:
$ INITIALIZE DB4:

PAYVOL4
DBi:, DB2:, DB3:, DB4:
_$PAYVOL1, PAYVOL2, PAYVOL3, PAYVOL4/SYSTEM
$ MOUNT/BIND=MASTER_SET

Note that the first device/volume pair listed in the MOUNT /BIND command
is the root volume of the set. When you add a volume to a set while
mounting the set, you must list the root volume first.
Note: Once a volume is bound into a volume set, it cannot be "unbound."

You can add volumes to an existing volume set at any time. The maximum
number of volumes in a set is 255.

3.4.3

Mounting a Magnetic Tape Volume
When mounting a magnetic tape volume, specify, along with the MOUNT
command, the following: any qualifiers you choose; a device name; and,
optionally, a label and logical name.
For a discussion of how to mount magnetic tape volume sets, see Section
3.4.4.
The next two sections describe procedures and commands for mounting
single-volume, ANSI-labeled, magnetic tapes.

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3.4 Mounting a Volume

3.4.3.1

Mounting an ANSI-Labeled Volume
When you use the MOUNT command to mount a magnetic tape volume,
VMS software checks to see whether the volume has a VMS or a nonVMS ANSI-labeled format. If the format is ANSI-labeled, the following are
checked:

•

The volume identifier field

•

The protection on the ANSI-labeled volume as described in Section 2.1.3.

Mount an ANSI-labeled volume by including the device name and volume
identifier as follows (specifying a logical name is optional):
$ MOUNT MT: ELAINE ET
%MOUNT-I-OPRQST, please mount volume ELAINE in device $MTA1:
Y.MDUNT-I-MOUNTED, ELAINE mounted on MTA1:
%MOUNT-I-RQSTDON, operator request canceled -- mount completed successfully

MOUNT finds an available MT drive, MTAl, and requests operator assistance.
The message displayed at the user terminal indicates which drive has been
selected. At this point, you (or the operator) load the magnetic tape on the
drive, and the mount operation completes. No operator response is necessary.
The display informs you that the volume named ELAINE is mounted on the
drive MTAl. Although not indicated in the message, MOUNT also assigns
the logical name ET to the volume ELAINE.
When used with the MOUNT command, the qualifiers described in the next
section affect the label format of a volume or of the magnetic tape file system
used to process an ANSI-labeled volume, or both. Unless otherwise noted,
you must have VOLPRO privilege to use any of these qualifiers when the
volume is a VMS ANSI-labeled volume containing protection that restricts
your process from accessing the volume.

3.4.3.2

Using MOUNT Command Qualifiers
This section describes some of the command qualifiers you can use when
mounting a magnetic tape volume. For a complete list of all the command
qualifiers supported for the mounting of magnetic tape volumes, see the VMS
Mount Utility Manual.
/BLOCKSIZE=n

Use the /BLOCKSIZE=n qualifier to specify the block size for the magnetic
tape. The range of valid values for n varies and depends on the density of the
volume, whether the data is for input or output, and whether the operation
uses RMS.
By default, VMS writes 2048-byte blocks, which conforms to the ANSI
standard. Although the VMS operating system allows you to specify a block
size larger than 2048 bytes, a larger block size does not conform to ANSI
standards.
You must specify /BLOCKSIZE when mounting volumes that do not support
the second file header label as defined in the ANSI standard or that support
a block size smaller than 2048 bytes. For example, you must specify
/BLOCKSIZE=512 to mount an RT-11 volume.

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If you want to write files on a magnetic tape volume, use the /BLOCKSIZE
qualifier to set the block size to other than 2048. If you want only to read
files from a magnetic tape volume, you do not have to use the /BLOCKSIZE
qualifier, since VMS will automatically handle the block size given by the
second file header label.

The minimum blocksize for ANSI standard magnetic tapes is 18, while the
maximum is 2048. The minimum blocksize for VMS magnetic tapes is 14,
while the maximum is 65,532.
/FOREIGN

The /FOREIGN qualifier should be used when a magnetic tape volume is not
in standard ANSI or ISO format or when a disk volume is not in Files-11
format.
/OVERRIDE

The /OVERRIDE=(option[, ... ]) qualifier inhibits one or more of the access
checks performed by MOUNT and the magnetic tape file system. The options
are as follows:
•

ACCESSIBILITY - If the installation allows, this option will override any
character in the accessibility field of the volume and file header labels.
The necessity of this qualifier is defined by the installation. That is, each
installation has the option of specifying a routine that the magnetic tape
file system will use to process this field. By default, the VMS operating
system provides a routine that checks this field in the following manner:
•

If the magnetic tape was created on a version of the VMS operating
system that conforms to Version 3 of ANSI, then this option must be
used to override any character other than an ASCII space.

•

If a VMS protection is specified and the magnetic tape conforms to an
ANSI standard that is later than Version 3, then this option must be
used to override any character other than an ASCII 1.

For more information on accessibility-based protection for VMS ANSIlabeled magnetic tapes, see Chapter 2.
•

EXPIRATION - Overrides the expiration dates of a volume and its files.
Use this qualifier when the expiration date (in the first file-header label)
of any file that you want to overwrite has not been reached.

•

IDENTIFICATION - Overrides the volume identifier in the volume
label. Use this qualifier to mount a volume for which you do not specify
the volume identifier. Only the volume identifier field will be overridden.
Volume protection, if any, is preserved.

•

OWNER-1DENTIFIER - Overrides the processing of the owner
identifier field. You use this option when you need to interchange
protected magnetic tapes between VMS and other DIGITAL operating
systems.

•

SETID - Prevents MOUNT from checking the file-set identifier in the
first file-header label of the first file on a continuation volume. Use this
qualifier only for ANSI-labeled volumes on which the file-set identifier of
the first file on a continuation volume differs from the file-set identifier of
the first file of the first volume that was mounted.

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Preparing Volumes for Private Use
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/0WNER_UIC=uic

The /OWNER_UIC=uic qualifier overrides the UIC written in the second
volume label and assigns the UIC you specify while the volume is mounted.
For magnetic tape volume sets in which a continuation volume is written,
the UIC specified at mount time is written to the volume only if the
/PROTECTION qualifier was specified either at mount time or when the
volume was initialized. This does not change the protection on any volumes
already created.
You can specify the UIC variable in the format:
[g,m]
g

is either an octal number in the range 0 through 37776 that denotes
the group number or an alphanumeric value (consisting of 1 through 31
characters) that describes the group.

is either an octal number in the range 0 through 177776 that denotes
the member number or an alphanumeric value (consisting of 1 through 31
characters) that describes the member.

Either square ( [ ] ) or angle ( < > ) brackets are required in the UIC
specification. For more details on VIC-based protection, see Chapter 2.
/CACHE=TAPE_DATA

The /CACHE qualifier with the TAPE_DATA option enables the write cache
for a tape device if the tape controller supports one. /NOCACHE is the
default for mounting tape devices. You must specify TAPE_DATA to enable
the write cache. If the tape controller does not support a write cache, the
option is ignored. This lets you specify /CACHE=TAPE_DATA in command
procedures that work with a variety of devices and controllers.
This option enables a form of controller-based, write-back caching. The
write-back caching feature significantly improves the overall performance of
streaming tape drives. Under some rare failure conditions, however, some
written data can be lost in the cache of the controller. If a failure occurs, the
magnetic tape being written becomes seriously flawed or unreadable, and
you must repeat the entire process used to write to the tape. When a failure
occurs, you are always notified with an error message.
/PROTECTION=code

The /PROTECTION=code qualifier overrides the VMS protection written
in the second volume label and assigns the protection code you specify to
the volume while it is mounted. For magnetic tape volume sets in which
a continuation volume is written, the protection code you specify will be
written to the continuation volume. By default, your process UIC also will be
written to the continuation volume unless you explicitly specify an alternate
UIC with the /OWNER_UIC qualifier described above.
Valid protection codes include READ and WRITE access for GROUP and
WORLD users; EXECUTE and DELETE access are not applicable to magnetic
tape volumes. SYSTEM users and the volume owner always have READ and
WRITE access to magnetic tape volumes regardless of the protection code that
you specify. Section 2.2.2 describes access and protection codes.

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Preparing Volumes for Private Use
3.4 Mounting a Volume

/HDR3

The /NOHDR3 qualifier controls whether special VMS header labels are
written to a volume. Privilege is not required for this qualifier. The default is
/HDR3, which allows VMS header labels to be written to a volume. When
the /NOHDR3 qualifier is used, long VMS file names are truncated to 17
characters. Use the /NOHDR3 qualifier when writing to volumes that will be
read by a system other than VMS, such as the RT-11 system, which does not
process all file-header labels correctly.
/RECORDSIZE=n

The /RECORDSIZE=n qualifier specifies the number of bytes in each record.
This qualifier does not require privilege. Use this qualifier when you mount
volumes without the second file-header label (such as RT-11 volumes), or
when you mount volumes with the /FOREIGN qualifier, to provide RMS
with the size of fixed-length records or the maximum size of variable-length
records.
The record size must be less than or equal to the specified or default block
size. Refer to the /BLOCKSIZE qualifier (described previously) for details.
The VMS operating system does not write records smaller than 14 bytes on
output. However, the VMS Convert Utility, described in the VMS Convert
and Convert/Reclaim Utility Manual, allows you to pad and extend the size of
records up to and greater than the 14-byte minimum.
Two other qualifiers that are important for mounting magnetic tape volumes
are /AUTOMATIC and /INITIALIZE. These qualifiers are described in the
following sections.

3.4.4

Mounting a Magnetic Tape Volume Set
When mounting a magnetic tape volume set, begin by following the
procedures described in Section 3.4.3 for mounting a single magnetic tape
volume. The number of volume identifiers need not equal the number of
device names specified. Thus, when you mount a magnetic tape volume set,
you can specify more volume identifiers than device names or more device
names than volumes.
The number of devices you specify directly affects the action taken by the
magnetic tape file system when processing continuation volumes in a volume
set. For example, when the number of devices is greater than the number
of volumes, the magnetic tape files system requests a continuation volume
to be mounted on the first drive from the list that does not have a volume
mounted.
The next two sections describe how to create and mount a magnetic tape
volume set. The manner in which continuation volumes are handled by the
magnetic tape file system is also described.

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3.4 Mounting a Volume

3.4.4.1

Creating a Magnetic Tape Volume Set
If you do not create a volume set explicitly, the VMS system creates one
when necessary. If you have not mounted a volume set and a continuation
volume is required, the magnetic tape file system requests that a continuation
volume be mounted and implicitly creates a volume set. For example, if the
magnetic tape file system encounters an EOT mark while writing a volume,
it sends a message to the operator console requesting that another volume be
mounted.

After you mount the next volume, the magnetic tape file system writes the
volume and header labels and then reissues the pending write requests to the
continuation volume. The file-set identifier in the first file-header label of all
files written to the continuation volume is the file-set identifier of the first file
on the first volume. The file-set identifier for VMS volume sets is always that
of the first file of the first volume that was mounted in the set.
To explicitly create a volume set with three volumes, follow this procedure:

Allocate a drive on which you will load each volume by entering the
following ALLOCATE commands:
$ALLOCATE MTAO:
%DCL-I-ALLOC, _MARS$MTAO: allocated
$ALLOCATE MTA1:
%DCL-I-ALLOC, _MARS$MTA1: allocated
$ ALLOCATE MTA2:
%DCL-I-ALLOC, _MARS$MTA2: allocated

Initialize the volumes. You should specify the density and the access
protection in addition to the device name and the volume identifier in the
INITIALIZE commands, as in the following command lines:
$ INITIALIZE/DENSITY=1600/PROTECTION=(G:RW) MTAO: TAPE1
$ INITIALIZE/DENSITY=1600/PROTECTION=(G:RW) MTA1: TAPE2
$ INITIALIZE/DENSITY=1600/PROTECTION=(G:RW) MTA2: TAPE3

Mount the volumes by entering the following MOUNT command. You
should include the device name and volume identifier. Specifying a
logical name for the volume set is optional.
$MOUNT MTAO: ,MTA1: ,MTA2: TAPE1,TAPE2,TAPE3 TEST
%MOUNT-I-MOUNTED, TAPE1 mounted on _MTAO:
%MOUNT-I-MOUNTED, TAPE2 mounted on _MTA1:
%MOUNT-I-MOUNTED, TAPE3 mounted on _MTA2:

The system not only confirms which volumes have been mounted but
also indicates on which drive each volume has been mounted.
The system mounts and verifies only the volumes that are physically
loaded on the drives at mount time. However, the volume identifiers of
additional volumes that you specify are not verified until the volumes are
accessed.
You can check the densities, volume labels, UICs, and relative volume
numbers of the volumes that are mounted on drives. To do so, specify the
SHOW DEVICES/FULL command. If you specify a generic device code
for the magnetic tape drives, such as MT, information for all the drives of
that type configured in the system is displayed. To display information for
a volume mounted on a specific drive, specify the physical device code,
consisting of the generic device code, the controller designation, and the unit
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Preparing Volumes for Private Use
3.4 Mounting a Volume

number followed by a colon. For more information on the SHOW DEVICES
command, including examples of displays returned by the SHOW DEVICE
/FULL command, see Chapter 4 and the VMS DCL Dictionary.
3.4.4.2

Mounting Continuation Volumes in a Volume Set

When mounting a magnetic tape volume set, follow the general procedures
described in the previous section for creating a magnetic tape volume set.
Once the volume set has been created, however, there is no need to initialize
the volumes in the set when you mount the volume set.
You need not allocate a drive for each volume in the volume set. The
magnetic tape file system requests that volumes be switched to appropriate
drives when continuation volumes are required.
The VMS operating system stores, but cannot verify, the volume identifiers of
volumes you specify but do not physically mount on drives at mount time.
VMS later verifies the volume identifiers of such volumes when the volumes
are accessed.
The VMS operating system supports the continuous processing of mounted
volumes in a magnetic tape volume set through automatic volume switching.
To do this, the magnetic tape file system uses automatic volume recognition
(AVR) and automatic volume labeling (AVL).
To take advantage of this automatic volume switching capability, you must
have more than one magnetic tape drive allocated to your volume set.
If you have two or more magnetic tape drives allocated to a volume set,
the magnetic tape file system switches volumes for you automatically by
sequentially selecting the next magnetic tape drive allocated to the volume
set. The magnetic tape file system expects the next volume in the volume set
to be loaded on that drive.
If the file system is writing to the volume set, it creates a label for the
magnetic tape and initializes the magnetic tape with that label and with the
protection characteristics set for the first of the volume set. If the magnetic
tape file system is reading the volume set, it generates the label and tries to
mount the next magnetic tape with that label. If the drive has no magnetic
tape loaded on it, or the wrong magnetic tape, the magnetic tape file system
sends a message to the operator console notifying the operator to either
mount a magnetic tape or mount the correct magnetic tape.

Before processing continuation volumes, the magnetic tape file system
processes the protection on that volume (as described in Section 2.1.3). If
the magnetic tape file system determines that the user does not have access to
the volume, then a message is sent to the operator to take some action.
The label generated fills the six-character volume identifier field. The first four
characters of the field contain the first four characters of the label specified
for the previous volume in the volume set. (If the label is less than four
characters, the volume identifier field is padded with underscores.) The fifth
and sixth characters contain the relative volume number for that reel in the
volume set. Note that this allows VMS to generate only 99 unique labels for
a given volume set.
With automatic volume switching enabled, the operator can load a magnetic
tape on the next drive allocated to the magnetic tape volume set anytime
before the volume being processed reaches the EOT mark. The magnetic tape
file system mounts and initializes (if INITIALIZE was specified originally) the
next magnetic tape in the volume set and then notifies the operator that the
switch has occurred.

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Preparing Volumes for Private Use
3.4 Mounting a Volume

In the following example, the volume with the identifier TAPE is mounted on
MTAO:
$MOUNT MTAO: ,MTA1: ,MTA2:

TAPE

Continuation volumes for this set should be loaded on the magnetic tape
drives in the following order: MTAl, MTA2, MTAO, MTAl, MTA2, and so
forth.
To explicitly override automatic volume switching, specify the
/NOAUTOMATIC qualifier when mounting a magnetic tape volume. The
default is /AUTOMATIC. If you allocate only one drive to the magnetic tape
volume set, you implicitly disable automatic volume switching.
To ensure that any volume added to the magnetic tape volume set will
be initialized prior to being written to, mount the volume with the
/INITIALIZE=CONTINUATION qualifier. The default is /NOINITIALIZE.
The next example demonstrates the use of the
/INITIALIZE=CONTINUATION qualifier for mounting volume sets. It
also shows how volume identifiers are generated for continuation volumes.
$ INITIALIZE MTAO: MAIN
$ MOUNT/OVERRIDE=IDENTIFIER/INITIALIZE=CONTINUATION MTAO: ,MTA1:

The volume labeled MAIN is mounted on MTAO. The second volume in
the set receives the volume identifier MAIN02 and is mounted on MTAl.
The third volume in the set receives the volume identifier MAIN03 and is
mounted on MTAO. In the following example, the first volume in the set
is labeled SUN and is mounted on MTAO. The second volume receives the
identifier SUN_02 and is mounted on MTAl. The third volume receives the
identifier SUN _03 and is mounted on MTAO:
$ MOUNT MTAO: ,MTA1: SUN

The next example illustrates a continuation volume with two volume
identifiers.
$ MOUNT MTAO: ,MTA1: SUN.MOON

In this case, SUN and MOON are mounted on MTAO and MTAl respectively.
If a third volume is added to the set, it will be given the identifier MOON03
and be mounted on MTAO.

3.5

Dismounting a Volume
When you have finished processing the files or data on your disk or magnetic
tape volume, you can use the DISMOUNT command to explicitly dismount a
single volume or an entire volume set.
If you explicitly dismount a single volume in a volume set, VMS dismounts
all the volumes in the set. For disk volume sets, however, it is possible to
explicitly dismount a single volume in the volume set without dismounting
the entire set. To do this, you must use the /UNIT qualifier.

When you enter the DCL command DISMOUNT, the volume is automatically
unloaded from the drive. You can override this automatic unloading of your
volume by specifying the /NOUNLOAD qualifier with the DISMOUNT
command.

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Preparing Volumes for Private Use
3.5 Dismounting a Volume

Even when you specify the /NOUNLOAD qualifier with the DISMOUNT
command, your volume is still logically dismounted from the drive;
however, the volume remains physically loaded on the drive. If you use
the /NOUNLOAD qualifier to dismount a magnetic tape volume, the volume
remains loaded on the magnetic tape drive and the magnetic tape reel is
rewound to the BOT mark.
If you plan to remount or reinitialize a volume you are dismounting, you can
save time and eliminate unnecessary handling of that volume by using the
/NOUNLOAD qualifier with the DISMOUNT command.

The following examples show how to use the DISMOUNT command. The
first example employs the /NOUNLOAD qualifier.
$ DISMOUNT/NOUNLOAD MTA1:
$

In this example, the magnetic tape volume is logically dismounted and
remains loaded on drive MTAl. Also, the magnetic tape reel is rewound to
the BOT mark. The VMS operating system returns you to DCL level.
The DISMOUNT command is also used to dismount foreign volumes. The
following command dismounts a volume that had been mounted with the
/FOREIGN qualifier on DBAO:
$ DISMOUNT DBAO:
$

In this example, the volume that had been mounted with the /FOREIGN
qualifier on DBAO is dismounted and automatically unloaded. The VMS
system returns you to DCL level.
As mentioned previously, use the DISMOUNT command to dismount
an entire volume set. If you explicitly dismount any volume in a disk or
magnetic tape volume set, the entire volume set is dismounted. For example,
if you had a volume set that consisted of DBA3 and DBA4 and you entered
the following command, the entire volume set would be dismounted:
$ DISMOUNT DBA3:

You should always explicitly dismount a volume or volume set with the
DISMOUNT command, or with a command procedure containing that
command, before physically unloading that volume.
A volume is dismounted and unloaded automatically if you log out of the job
from which you had mounted the volume. If the system fails, however, the
drive is not automatically dismounted.
Note that data corruption can occur if a volume has not been explicitly
dismounted and the system fails. For magnetic tape volumes, data corruption
can occur if you unload a volume that contains an open file for which filetrailer labels have not been written. When you remount the volume and
attempt to access the file without file-trailer labels, you receive the following
error message:
%MTAACP-magnetic tape position lost

You will be able to access all the files (on that magnetic tape volume)
preceding the file whose file-trailer labels had not been written. However,
you will not be able to access the file without file-trailer labels.

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3.5 Dismounting a Volume

Note that the dismount of a volume is done by the file system and is not
complete until all the open files on the volume have been closed. Thus,
a substantial amount of time can pass between the time you enter the
DISMOUNT command and the completion of the dismount. Always wait
for the drive to unload before you remove the volume. (You can verify that
the dismount is complete by entering the DCL command SHOW DEVICES.)
If the device you are dismounting was allocated with an ALLOCATE
command, it remains allocated after it is dismounted with the DISMOUNT
command. If the device was implicitly allocated by the MOUNT command,
the DISMOUNT command deallocates it.

For more information on the DISMOUNT command, see the VMS DCL

Dictionary.

3.6

Deallocating Drives
The process of allocation reserves a device for exclusive use by your process.
The device remains allocated to your process until you explicitly deallocate it
or until you log out from your process. Once you have allocated the device,
other users cannot access that device until you explicitly deallocate it or log
out.
Use the DCL command DEALLOCATE to explicitly deallocate a disk drive or
magnetic tape drive that has been allocated to your process. A complement to
the ALLOCATE command, the DEALLOCATE command logically disconnects
a drive from your process and returns it to the pool of devices.
The following example shows how to explicitly deallocate a magnetic tape
drive or a disk drive:
$ DEALLOCATE MTA1:
$

In this example, the DEALLOCATE command logically disconnects magnetic
tape drive MTAl from your process. The VMS operating system returns you
to DCL level.
Since logging out of a process from which drives have been allocated
automatically deallocates all explicitly and implicitly allocated drives, you
do not have to explicitly deallocate a disk or magnetic tape drive that
has been allocated to your process. However, it is a good practice to use
the DEALLOCATE command (or a command procedure containing this
command) to explicitly deallocate all the drives you allocated with the
ALLOCATE command.

3. 7

Using Command Procedures to Set Up Volumes
Since private disk and magnetic tape volumes frequently must be set up
before you can perform operations on them, you may want to design
command procedures to facilitate the set-up procedures. This section
contains examples of command procedures that can be used to set up disk
and magnetic tape volumes for routine operations.
You can tailor command procedures to meet the needs of your own set-up
tasks. The command procedure examples in this section, although general in
nature, can serve as guiding strategies for you.

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3. 7 Using Command Procedures to Set Up Volumes

The next two sections contain examples of command procedures designed to
set up disk and magnetic tape volumes for routine processing.

3.7.1

Designing Command Procedures to Set Up Disk Volumes
The following command procedure is designed to allocate, initialize, and
mount a disk volume. You can use a text editor, such as EDT or EVE, to
create a file to contain your command procedure. Assume that a file named
SETUP.COM has been created and that it contains a very basic command
procedure, which, when executed, allocates and mounts a disk. Construct this
command procedure by entering the following text:
$ ! Place a disk fn the drive
$ IF Pi .EQS. "" THEN INQUIRE Pi "enter device name"
$ IF P2 .EQS. "" THEN INQUIRE P2 "enter volume label"
$ IF P3 .EQS. "" THEN INQUIRE P3 "enter logical name"
$ ALLOCATE 'Pi,
$MOUNT 'Pi' 'P2' 'P3'

This command procedure, although very simple, accomplishes the task of
allocating and mounting a disk each time it is executed. It is designed to
prompt you for the device name, volume label, and logical name of the disk
device that you want to allocate and mount. By assigning logical names
to your disks, you can use this command procedure to allocate and mount
devices over and over again.
You can take further advantage of the power of a command procedure by
including a few additional tasks as well. For example, you could design the
SETUP.COM command procedure to deallocate and dismount the disk. The
command procedure example used to set up a magnetic tape (described in the
next section) takes advantage of some of these options.
To execute the SETUP.COM command procedure, enter the following
command:
©SETUP

You can also write command procedures to mount a volume from a batch
job. By using logical names to refer to devices and files, you can use the same
command procedures without modification each time you want to access a
volume.
For example, if you use the same RK07 disk pack to back up your files on a
weekly basis, you can submit as a batch job a command procedure such as
the following:
$ MOUNT DM: BACK_UP_GMB RK
$ BACKUP/REPLACE *·* RK:*.*
$ DIRECTORY/FULL/OUTPUT=BACKUP.LOG RK:
$ DISMOUNT RK:

In this command procedure, the MOUNT command finds and allocates a
device of the type OM and creates a logical name RK. The MOUNT command
substitutes the equivalence name in the message displayed at the operator
console.
When the MOUNT command notifies the operator to mount the correct
volume, the job waits until the operator responds. When the operation is
completed, the DISMOUNT command dismounts the device RK.

3-21

Preparing Volumes for Private Use
3. 7 Using Command Procedures to Set Up Volumes

3.7.2

Designing Command Procedures to Set Up Magnetic Tape Volumes
The command procedure below, which is more sophisticated and detailed
than the previous example, is designed to set up a magnetic tape for
processing. The ALLOCATE and MOUNT/FOREIGN commands are
included in this command procedure. Using a text editor, construct the
command procedure in the following way:
$ ! First mount the tape on the drive
$ ON CONTROL_Y THEN GOTO EXIT
$ ON ERROR THEN GOTO EXIT
$WRITE SYS$0UTPUT "Welcome to FETCH."
$ WRITE SYS$0UTPUT II II
$Li: INQUIRE/NOPUNC PHYS "Have you placed the volume in the drive? "
$ IF .NOT. PHYS THEN GOTO Li
$ INQUIRE/NOPUNC DRIVE "Which drive is the volume mounted on? "
$DRIVE= DRIVE - ":"
$ ALLOCATE 'DRIVE'
$ MOUNT/FOREIGN 'DRIVE'
$ ON ERROR THEN GOTO COMMAND_LOOP
$ !

$ COMMAND_LOOP:

INQUIRE/NOPUNC OPTION "FETCH> "

$ IF OPTION .EQS. "DIR" THEN GOTO DIR
$ IF OPTION .EQS. "EXIT" THEN GOTO EXIT
$ IF OPTION .EQS. "FETCH" THEN GOTO FETCH
$ IF OPTION .EQS. "HELP" THEN GOTO HELP
$ IF OPTION .EQS. "LIST" THEN GOTO LIST
$ GOTO COMMAND_LOOP
$ !

$ DIR: INQUIRE SPEC "Filespec"
$ DIR 'SPEC'
$ GOTO COMMAND_LOOP
$ HELP:
$WRITE SYS$0UTPUT "Enter any of the following commands at the prompt:"
$ WRITE SYS$0UTPUT II II
$ WRITE SYS$0UTPUT II II
$WRITE SYS$0UTPUT "DIR
(To search for a file)"
$ WRITE SYS$0UTPUT II II
$WRITE SYS$0UTPUT "EXIT
(To exit this program)"
$ WRITE SYS$0UTPUT II II
$WRITE SYS$0UTPUT "FETCH
(To perform a BACKUP RESTORE operation)"
$ WRITE SYS$0UTPUT II II
$ WRITE SYS$0UTPUT "HELP
(To read this text)"
$ WRITE SYS$0UTPUT II II
$ WRITE SYS$0UTPUT "LIST
(To perform a BACKUP LIST operation)"
$ GOTO COMMAND_LOOP
$ !

$ FETCH: INQUIRE FILE "Filespec"
$ INQUIRE SAVESET "Save set name"
$LINE:= BACKUP/LOG 'DRIVE':'SAVESET'/SELECT='FILE'
$ INQUIRE EXCLUDE "Enter any filespecs you want excluded"
$ IF EXCLUDE .EQS. "" THEN GOTO L2
$LINE := 'LINE'/EXCLUDE=('EXCLUDE')

3-22

Preparing Volumes for Private Use
3. 7 Using Command Procedures to Set Up Volumes

$ !

$ L2: INQUIRE/NOPUNC TO "Where do you want the file (s)? ( ~ for current directory)"
$ IF TO .EQS. "" THEN GOTO REPLACE
$ LINE := 'LINE' 'TO'
$ GOTO L3
$ REPLACE: LINE := 'LINE' []
$ !

$ L3: INQUIRE/NOPUNC NEW "Create a new version if file already exists? "
$ IF .NOT. NEW THEN GOTO NOT
$LINE := 'LINE'/NEW_VERSION
$ !

$ NOT: LINE := 'LINE'/OWNER_UIC=ORIGINAL
$ LINE
$ GOTO COMMAND_LOOP
$ !

$ LIST: INQUIRE SPEC "Filespec"
$ INQUIRE SAVESET "Save set name"
$ INQUIRE/NOPUNC OUTPUT "What do you want to call the list file? ( ~ for SYS$0UTPUT ")
$ IF OUTPUT .EQS. "" THEN GOTO NOOUT
$LINE := BACKUP/LIST='OUTPUT' 'DRIVE' :'SAVESET'/SELECT=('SPEC')
$ GOTO L4
$ NOOUT: LINE:= BACKUP/LIST 'DRIVE':'SAVESET'/SELECT=('SPEC')
$ !

$ L4: INQUIRE EXCLUDE "Enter any filespecs you want excluded"
$ IF EXCLUDE .EQS. "" THEN GOT L5
$LINE := 'LINE'/EXCLUDE=('EXCLUDE')
$ !
$ L5:

LINE
$ GOTO COMMAND_LOOP
$ !
$ EXIT:

$ DISMOUNT 'DRIVE'
$ DEALLOCATE 'DRIVE'

Assume this command procedure is contained in a file named FETCH.COM;
you would execute this command procedure by entering the following:
©FETCH

This command procedure is more complex than the two previous ones, which
were both used to set up a disk. As with the former command procedures,
the procedure contained in FETCH.COM also accomplishes the basic task of
allocating the device and mounting the volume.
In addition to its allocating and mounting functions, the command procedure
contained in FETCH.COM is designed to prompt you for input. For example,
it specifically asks you if the magnetic tape is on the drive. Also, note that
this command procedure is designed to do a BACKUP restore operation. It
prompts you for specific options on the restore operation.
Finally, this command procedure explicitly dismounts your magnetic tape
volume and deallocates the drive after your task has completed.

3-23

Manipulating Files

You can manipulate disk and magnetic tape files by using the DIGITAL
Command Language (DCL). In particular, you can use DCL commands to
perform the following tasks:
•

Retrieve disk and magnetic tape file information

•

Modify disk and magnetic tape file characteristics

•

Access files residing on disk and magnetic tape volumes

DCL commands enable you to manipulate files in the following ways:
•

SHOW commands retrieve disk and magnetic tape file information, such
as device and protection characteristics, and display this information on
your terminal.

•

SET commands modify disk and magnetic tape file characteristics, such as
protection or UIC information.

•

The DCL command language can be used to access disk and magnetic
tape files for read or write operations.

In addition to manipulating files through DCL, you can write user programs to
assist you in routine file-manipulation tasks. You can write these programs in
either VAX MACRO or in one of the higher-level languages supported by the
VMS operating system. If you want to manipulate individual records within
files - that is, to access files at the record level - you should write programs
that include RMS facilities. Examples of the RMS facilities used to manipulate
files at the record level are included in the VMS Record Management Services

Manual.
You can use DCL to manipulate disk and magnetic tape files at the file level.
Note the following restrictions on the use of DCL commands for manipulating
files on disk and magnetic tape volumes:
•

The SUBMIT command cannot access files on allocated devices. You
can submit files on private disk volumes if you mount the volume as a
shareable volume. To submit a file on a magnetic tape volume, you first
must copy the file to a shared disk volume and then submit it from the
disk.

•

You can print a file from a privately owned volume. Note, however, that
the volume containing the file you wish to print must remain mounted
until after the file has completed printing. If you do not want to wait
until the printing completes, you can copy the file directly to the line
printer, using the DCL command COPY as in the following example:
$ COPY MYPHILE.DAT LPAO:

•

Most DCL commands require file-structured devices. For a list of those
commands that do not require file-structured devices, see the VMS DCL

Dictionary.

4-1

Manipulating Files

•

You can execute a command procedure that resides on a magnetic tape
volume as long as the procedure does not invoke other procedures and
does not issue any GOTO commands that refer to labels in the procedure
preceding the GOTO command. In this case, it would be better to copy
the command procedure from the magnetic tape volume to a local disk
from which you can then invoke the command procedure.

Note that you cannot use DCL commands to read or write files that are not
in the standard formats supported by VMS (these formats are described in
greater detail in the Guide to Using VMS Command Procedures).

4.1

Using DCL to Retrieve File Information
The DCL command language provides commands that enable you to retrieve
information about disk and magnetic tape files, volumes, and devices. You
can use the following DCL commands to retrieve such information:

•

DIRECTORY

•

SHOW DEVICES

•
•
•
•

SHOW MAGTAPE
SHOW ACL
SHOW PROTECTION
SHOW QUOTA

See the VMS DCL Dictionary for a complete list of the command qualifiers and
parameters applicable to each of these DCL commands.

4.1.1

Retrieving Directory Information
Use the DCL command DIRECTORY to retrieve information about a file or a
group of files residing on a disk or magnetic tape volume.
You can use the DIRECTORY command to list the names of all of the files in
a particular directory, or you can use it in conjunction with a file specification
to list the names of specific files in a given directory. When you include
certain command qualifiers along with the DIRECTORY command, you can
retrieve information in addition to the names of the files. See the VMS DCL
Dictionary for a list of qualifiers that can be used with the DIRECTORY
command.
The following examples illustrate three cases of retrieving information from
the [MALCOLM] directory, which resides on a disk with the logical name
DISK$DOCUMENT.

4-2

Manipulating Files
4.1 Using DCL to Retrieve File Information

Examples

$DIRECTORY AVERAGE.*
Directory DISK$DOCUMENT: [MALCOLM]
AVERAGE.EXE;6

AVERAGE.FOR;6

AVERAGE.LIS;4

AVERAGE.OBJ;12

Total of 4 files.

$ DIRECTORY/SIZE=USED/DATE=CREATED/VERSIONS=1/PROTECTION AVERAGE
Directory DISK$DOCUMENT: [MALCOLM]
AVERAGE.EXE;6
AVERAGE.FOR;6
AVERAGE.LIS;4
AVERAGE.OBJ;6

6
2
5
2

10-APR-1988 15:43 (RWED,RWED,RWED,RE)
2-APR-1988 10:29 (RWED,RWED,RWED,RE)
9-APR-1988 16:27 (RWED,RWED,RWED,RE)
9-APR-1988 16:27 (RWED,RWED,RWED,RE)

Total of 4 files, 15 blocks.

$ DIRECTORY/FULL/VERSIONS=!

[MALCOLM ... ]AVERAGE.EXE

Directory DISK$DOCUMENT: [MALCOLM]
AVERAGE.EXE;6
File ID: (4098, 149. 0)
[DOCUMENTATION.MALCOLM]
Size:
36/36
Owner:
Created: 27-JUN-1988 12:22:26.30
Revised: 27-JUN-1988 12:22:51.35 (2)
Expires:
<None specified>
Backup:
3-JUL-1988 22:03.09
File organization: Sequential
File attributes:
Allocation: 36, Extend: 36, Global buffer count: 0
No version limit
Variable length, maximum 255 bytes
Record format:
Record attributes: Carriage return carriage control
Journaling Enabled : None
File protection:
System:RWED, Owner:RWED, Group:RE, World:
Access Cntrl List: None
Total of 1 file, 36/36 blocks.
Directory DISK$DOCUMENT: [MALCOLM.TEST]
AVERAGE.EXE;!
File ID: (7714,29,0)
Owner:
[DOCUMENTATION.MALCOLM]
Size:
36/36
Created: 15-APR-1988 10:12
Revised: 15-APR-1988 10:12 (1)
Expires:
<None specified>
Backup:
15-APR-1988 22:41
File organization: Sequential
File attributes:
Allocation: 36, Extend: 36, Global buffer count: 0
No version limit
Record format:
Variable length, maximum 255 bytes
Record attributes: Carriage return carriage control
Journaling Enabled : None
System:RWED, Owner:RWED, Group:RE, World:
File protection:
Access Cntrl List: None
Total of 1 file, 36/36 blocks.
Grand total of 2 directories, 2 files, 72/72 blocks.

4-3

Manipulating Files
4.1 Using DCL to Retrieve File Information

Directory structures do not apply to magnetic tape volumes. However, you
can use the DIRECTORY command to search for files on magnetic tape
volumes. This use of the DIRECTORY command is also discussed in Section
4.3.2, which describes how to access magnetic tape files for read and write
operations.
To find the names of all files on a magnetic tape volume mounted on MTA2,
enter the following command:
$ DIRECTORY MTA2:

This directory command lists the file names and file types of all files on the
magnetic tape.
As in the case of the disk examples included above, you can use wildcard
characters in directory specifications for magnetic tapes, as in the following
command:
$DIRECTORY MFAO:*.*;*

In response to this command, the VMS operating system searches the entire
volume set and returns both ANSI and VMS file names. (The difference
between these two types of magnetic tape files is described in Section 4.3.2).

4.1.2

Retrieving Device Information
Use the DCL command SHOW DEVICES to retrieve information about the
availability of devices on your system.
When you enter the SHOW DEVICES command without specifying a device
or using a qualifier, information about all devices on the system is displayed.
If you specify a device name, SHOW DEVICES displays information about
that device. If you use certain qualifiers with SHOW DEVICES, information
is displayed about those devices that currently have volumes mounted or that
have been allocated to processes. See the VMS DCL Dictionary for a list of
qualifiers that can be used with the SHOW DEVICES command.
The device name displayed by the system uses the format ddcu, where dd is
the device code, c is the control, and u is the unit. If the system is part of
a VAXcluster environment, the device name includes the node name in the
format node$ddcu; where, node refers to the node name of the system that
the device resides on, dd refers to the device type, c refers to the controller
designation, and u refers to the unit number. See the VMS VAXcluster Manual
for a complete description of the device name format on clusters.
The following examples illustrate three instances of how the SHOW DEVICES
command can be used.

4-4

Manipulating Files
4.1 Using DCL to Retrieve File Information

Examples

$ SHOW DEVICES

Device
Status
Mounted
Mounted
Mounted
Mounted
Online
Mounted
Online
Online
Online
Online
Mounted
Online
Online
Mounted
Online

Device
Name
DBAO:
DBA1:
DBA2:
DBA5:
DBA6:
DBA7:
DMAO:
DLAO:
DYAO:
DYA1:
DRA3:
MFAO:
MFA1:
MTAO:
MTA1:

Error Volume
Count
Label
0 VMS
0 USERPACK1
3 DOCUMENT
0 MAS TERP
0
0 PROJECT
0
0
0
0
0 RES26APR
8
1
9 BACKUP
0

Free
Trans
Blocks Count
47088
115
45216
2
20
8068
28668
1

Mnt
Cnt
1
1
1
1

110547

29317

453

The SHOW DEVICES command displays the following information for each
device on the system:
•

Device name.

•

Device status and characteristics. (Status indicates whether the device is
on line; characteristics indicate whether the device is allocated, spooled,
or has a volume mounted on it and if the volume is mounted foreign.)

•

Error count.

•

Volume labels.

•

Number of free blocks on the volume (disk only).

•

Transaction count.

•

Number of mount requests issued for the volume.

$ SHOW DEVICES/FULL DMAO

Disk $1$DMAO: (NODE1), device type RK07, is online, allocated,
served to the cluster, error logging enabled.
Error count
Owner process
Owner process ID
Reference count
Allocation class

"SMITH"
24400133
1
1

Operations completed
4527
Owner UIC
[0,0]
Dev Prot
S:RWED,O:RWED,G:RWED,W:RWED
Default buffer size
512

This SHOW DEVICES command requests a full listing of the status of the
RK07 device DMAO. The device is located on NODEl in a VAXcluster.

4-5

Manipulating Files
4.1 Using DCL to Retrieve File Information

$ SHOW DEVICES/FULL NODE2$
Disk $1$DBAO: (NODE2), device type RP05, is online, mounted, file-oriented
device, shareable, served to cluster via MSCP Server, error logging is
enabled.
Error count
Owner process
Owner process ID
Reference count
Total blocks
Total cylinders
Allocation class
Volume label
Cluster size
Free blocks
Extend quantity
Mount status
Extent cache size
File ID cache size
Quota cache size

00000000
1

171798
411
1

"HIGHNOON"
3

94425
5

System
64
64
0

Operations completed
120
Owner UIC
[303,2]
Dev Prot
S:RWED,O:RWED,G:RWED,W:RWED
Default buffer size
512
Sectors per track
22
Tracks per cylinder
19
Relative volume number
0
Transaction count
1
Maximum files allowed
21474
Mount count
8
11
Cache name
_$255$DUA8:XQPCACHE"
Maximum blocks in extent cache
9442
Blocks currently in extent cache
0
Maximum buffers in FCP cache
421

Volume status: subject to mount verification, file high-water marking, writethrough caching enabled.
Volume is also mounted on NODE1, NODE4, NODE3.
Disk NODE2$DBC1:, device type RP06, is online, error logging enabled.
Error count
Owner process
Owner process ID
Reference count
Host name

00000000
0

"NODE2"

Operations completed
0
Owner UIC
[0,0]
Dev Prot
S:RWED,O:RWED,G:RWED,W:RWED
Default buffer size
512
Host type, available
V780, yes

Disk NODE2$DMAO:, device type RK07, is online, error logging enabled.
Error count
Owner process
Owner process ID
Reference count
Host name

""
00000000
0

"NODE2"

Operations completed
0
Owner UIC
[0,0]
Dev Prot
S:RWED,O:RWED,G:RWED,W:RWED
Default buffer size
512
Host type, available
V780, yes

The command line SHOW DEVICES /FULL NODE2$ produces a full display
of information about each device on NODE2 on the VAXcluster system.
Information is shown here only for the first three devices: a mounted device
and two that are not mounted.

4.1.3

Retrieving Magnetic Tape Device Information
You can use the DCL command SHOW MAGTAPE to display the current
characteristics and status of a specified magnetic tape device.
You can enter the SHOW DEVICES command to find available magnetic
drives on your system. The SHOW MAGTAPE or SHOW DEVICE
/FULL commands enable you to retrieve additional information about the
characteristics of a particular magnetic tape device.

4-6

Manipulating Files
4.1 Using DCL to Retrieve File Information

When you enter the SHOW MAGTAPE command at your terminal, you
receive the following prompt:
_Device:

You must then specify the name of the magnetic tape device for which you
want to display the characteristics and status.
The following example illustrates how the SHOW MAGTAPE command is
used to retrieve information about MTAO:
Example

$ SHOW MAGTAPE MTAO:
MTAO:,
device type TU77, is online, error logging is enabled

Error count
0
Operations completed
0
Owner process
" 11
Owner UIC
[0,0]
Owner process ID 0000000
Dev Prot S:RWED, O:RWED, G:RWED, W:RWED
Reference Count
0
Default buff er size
2048
Density
800
Format
Normal-11
Volume Status: no-unload on dismount, odd parity)

This SHOW MAGTAPE command displays the characteristics of the device
MTAO. Among other characteristics, it displays the device type, density, and
format.

4.1.4

Retrieving Disk File Protection Information
The DCL command SHOW PROTECTION displays the current process
default protection. This protection is applied to files created during your
terminal session or to batch jobs, where defaults from directories or previously
existing versions are not available.
You can change the default protection at any time with the SET
PROTECTION command. (The SET ACL and SET PROTECTION
commands are discussed in Section 4.3, which describes how to modify
file characteristics.)
This section is not applicable to magnetic tapes. Although you can use the
SHOW PROTECTION or SET PROTECTION commands to show or set
the default protection of magnetic tapes, the protection is not written to
the magnetic tape volume unless you specify the /PROTECTION= qualifier
with the INITIALIZE command when you are initializing the magnetic
tape volume. See the description of initializing magnetic tape volumes in
Chapter 3.
The next example illustrates how the SHOW PROTECTION command can
be used in conjunction with the SET PROTECTION command to display and
modify the protection characteristics of a disk file.

4-7

Manipulating Files
4.1 Using DCL to Retrieve File Information

Example
$ SHOW PROTECTION
SYSTEM=RWED, OWNER=RWED, GROUP=RE, WORLD=NO ACCESS
$SET PROTECTION=(GROUP:RWED,WORLD:RE)/DEFAULT
$ SHOW PROTECTION
SYSTEM=RWED, OWNER=RWED, GROUP=RWED, WORLD=RE

This SHOW PROTECTION command requests a display of the current
protection defaults. The SET PROTECTION/DEFAULT command is then
used to change the file access allowed to other users in the same group as
well as to miscellaneous system users.

4.1.5

Retrieving Disk Quota Information
Frequently, it is important to limit the amount of disk space certain users
consume. The VMS Disk Quota Utility (DISKQUOTA) gives the system
manager this capability. Users who have READ access to the quota file can
enter the SHOW QUOTA command to determine how much disk space any
user on the system has been allocated. Users who do not have READ access
to the quota file can use the SHOW QUOTA command to determine their
own allotments.
You can manage the checking on a per-volume basis at mount time by using
the MOUNT qualifier /[NO]QUOTA. (You can also use DISKQUOTA to
allow or disallow amounts of disk space.) You must have the VOLPRO user
privilege, or your UIC must match the UIC written on the volume, in order to
use the MOUNT command qualifier /QUOTA.
Enter the DCL command SHOW QUOTA to find out whether a quota exists
for any specific user on a specific disk. The display that results from the
SHOW QUOTA command gives the quotas used, authorized, and available.
A user can have a quota for any disk volume on the system. In some cases,
the user is permitted a certain authorized limit plus an overdraft limit.
Generally, only the authorized limit applies. However, certain system
programs, such as editors, can employ the overdraft feature when the
authorized limit is exceeded.
If you run out of disk space during the creation of a file, you receive a
system message. If you cannot obtain sufficient space by purging or deleting
unnecessary files, you may need to contact the system manager to increase
your disk quota. If you attempt to write a file to a spooled printer, you must
have WRITE access and have sufficient quota on the disk associated with that
printer.
Examples

$ SHOW QUOTA
User [DOCUMENTATION.MALCOLM] has 2780 blocks used, 7220 available,
of 10000 authorized and permitted overdraft of 500 blocks on DISK$

The SHOW QUOTA command displays the amount of disk space authorized,
used, and still available on the current default disk for the present user. The
permitted overdraft in this example is 500 blocks.

4-8

Manipulating Files
4.1 Using DCL to Retrieve File Information

$SHOW QUOTA /USER=[DOCUMENTATION,JONES]/DISK=XXX1:
%SYSTEM-F-NODISKQUOTA, no disk quota entry for this UIC

This SHOW QUOTA command displays the fact that the user with UIC
[DOCUMENTATION,JONES] has no disk quota allocation on device XXXl.
~

$ SHOW QUOTA /USER= [DOCUMENTATION ELAINE]
User [DOCUMENTATION.ELAINE] has 27305 blocks used, 2305 OVERDRAWN,
of 25000 authorized and permitted overdraft of 4000 blocks on DISK$
I

This SHOW QUOTA command illustrates a user with an overdrawn quota.

4.2

Using DCL to Modify File Characteristics
DCL provides commands that enable you to establish and modify the
characteristics of files residing on disk and magnetic tape volumes. The
following commands establish or modify file characteristics:
•

SET ACL

•

SET DIRECTORY (disk only)

•

SET FILE (disk only)

•

SET MAGTAPE (magnetic tape only)

•

SET PROTECTION (disk only)

•

SET VOLUME (disk only)

Each of these commands is discussed in detail in the Guide to Using VMS
Command Procedures. For a complete list of the command qualifiers and
parameters applicable to each of these DCL commands, see the VMS DCL
Dictionary.

4.2.1

Modifying Directory Characteristics
The DCL command SET DIRECTORY modifies the characteristics of one
or more directories. The following examples illustrate two uses of the SET
DIRECTORY command.
Examples

$ SET DIRECTORY/VERSION_LIMIT=5/CONFIRM [SMITH.FORTRAN]

In this example, the SET DIRECTORY command limits the number of
versions to five for files created after the command is issued. The /CONFIRM
qualifier requests that you confirm whether or not the specified directory
should actually be modified.
$ SET DIRECTORY/OWNER_UIC=[DOCUMENTATION,GRAY] [DAVIDSON], [USERS]

Here, the SET DIRECTORY command modifies both the [DAVIDSON] and
[USERS] directories, changing their owner UICs. Use of the /OWNER_UIC
qualifier requires SYSPRV or GRPPRV for changing the ownership at the
system or group level.

4-9

Manipulating Files
4.2 Using DCL to Modify File Characteristics

4.2.2

Modifying Disk File Characteristics
Use the DCL command SET FILE to modify the characteristics of one or more
files. The examples that follow illustrate three ways the SET FILE command
can be used to modify file characteristics.
Examples

$SET FILE/EXPIRATION_DATE=15-APR-1988:11:00 BATCH.COM;3

This SET FILE command requests that the expiration date of the file
BATCH.COM;3 be set to 11:00 A.M., April 15, 1988.
~

$SET FILE/BEFORE=15-APR-88/ERASE_ON_DELETE PERSONNEL*.SAL

This SET FILE command calls for all files that match the file specification
PERSONNEL•.SAL and that are dated before April 15, 1988. Disk locations
are erased for files that are deleted with commands such as DELETE or
PURGE.
$SET FILE/OWNER_UIC=[DOCUMENTATION,GRAY]/VERSION_LIMIT=100 MYFILE.DAT

This SET FILE command modifies the characteristics of the file MYFILE.DAT,
changing the owner UIC and assigning a file version limit of 100. Note that
the /OWNER_UIC qualifier requires SYSPRV or GRPPRV for changing the
ownership at the system or group level.

4.2.3

Modifying Magnetic Tape Device Characteristics
Use the DCL command SET MAGTAPE to define the default characteristics
associated with a specific magnetic tape device for subsequent file operations.
The device must not be currently allocated to any other user.
The following examples illustrate uses of the SET MAGTAPE command in
conjunction with the MOUNT command.
Examples

$MOUNT MTB1:/FOREIGN
$SET MAGTAPE MTB1: /DENSITY=800

The MOUNT command mounts a foreign tape on the device MTBl. The
SET MAGTAPE command defines the density at 800 bpi for writing to the
magnetic tape. (The density is reset only if the magnetic tape has never been
written before.)
~

$MOUNT MTAO:/FOREIGN
$SET MAGTAPE MTAO:/SKIP=FILES:4

The MOUNT command mounts a foreign magnetic tape on the device MTAO;
the SET MAGTAPE command directs the IJO subsystem to position the
magnetic tape to skip four files.
~

$MOUNT MTA1:/FOREIGN
$SET MAGTAPE/REWIND MTA1:

The MOUNT command mounts a foreign tape on the device MTAl; the SET
MAGTAPE rewinds the volume.

4-10

Manipulating Files
4.2 Using DCL to Modify File Characteristics

4.2.4

Modifying File Protection Characteristics
Use the SET PROTECTION command to change or reset the protection
characteristics for one or more files. If you include a protection code, the
file protection is changed to that specified in the code. When you omit
the protection code and do not use the /PROTECTION qualifier, the
file protection changes to the default file access established by the SET
PROTECTION/DEFAULT command. See the SET PROTECTION/DEFAULT
command for information on how to change the default file protection.
All disk and magnetic tape volumes have protection codes that restrict access
to the volume. The protection codes for magnetic tape volumes are assigned
with the INITIALIZE and MOUNT commands. Protection characteristics
on magnetic tape volumes cannot be changed by the SET PROTECTION
command.
For disk volumes, each file on the volume can have a different protection
associated with it. The SET PROTECTION command and other filemanipulating commands allow you to define the protection for individual
files.
If you omit both the code and the /PROTECTION file qualifier, your
current default protection (established by the SET PROTECTION/DEFAULT
command) is applied to the file.

The examples that follow illustrate using the SET PROTECTION command.
Examples

$ DELETE INCOME. DAT; 3
%DELETE-W-FILNOTDEL, error deleting DISK!: [SMITH]INCOME.DAT;3
-RMS-E-PRV, insufficient privilege or file protection violation
$ SET PROTECTION=OWNER:D INCOME.DAT;3
$ DELETE INCOME.DAT;3

The file INCOME.DAT;3 has been protected against deletion. This SET
PROTECTION command changes only the owner's DELETE access for the
file INCOME.DAT;3. Now the file can be deleted.
~

$ SET PROTECTION _$PAYROLL.LIS/PROTECTION=(SYSTEM:R,OWNER:RWED,GROUP:RW) ,_$PAYROLL.OUT/PROTECTION=(SYSTEM:RWED,GROUP:RWED,WORLD)

In this example, the SET PROTECTION command changes the protection
codes applied to two files. To the file PAYROLL.LIS, it gives the system
READ access, the owner READ, WRITE, EXECUTE, and DELETE access, and
users in the owner's group READ/WRITE access. To the file PAYROLL.OUT,
it gives the system and group all types of access; the current access for owner
does not change, but world is denied all types of access.

4-11

Manipulating Files
4.2 Using DCL to Modify File Characteristics
~

$ SET PROTECTION A.DAT, B.DAT/PROTECTION=OWNER:RWED, C.DAT

The SET PROTECTION command specifies that the file A.DAT should receive
the default protection established for the owner's files. The existing protection
for the file B.DAT is overridden, only for the OWNER category, to provide
READ, WRITE, EXECUTE, and DELETE access. Note that no protection is
specified for the file C.DAT at either the command or file level. Thus, like
A.DAT, C.DAT receives the default protection.
Since no version numbers are specified in this example, the protection settings
affect only the highest versions of the three files.
~

$ SET PROTECTION=OWNER:D _$[MALCOLM.SUB1]SUB2.DIR/PROTECTION=GROUP:D

This SET PROTECTION command changes the protection for the owner
and group categories of the subdirectory [MALCOLM.SUB1.SUB2] to permit
deletion. However, the protection for world and system categories is not
changed.

4.2.5

Modifying User Identification Code Characteristics
Although DIGITAL discourages it, you can use the DCL command SET UIC
to establish a new user identification code (UIC) as your default. To use this
command, however, you need a special privilege called Change Mode to
Kernel (CMKRNL).
If you have the appropriate privilege, you can use the SET UIC command to
gain access to a restricted file - that is, a file contained in a directory whose
protection restricts access to the owner of that directory. You can also use the
SET UIC command to gain access to a restricted magnetic tape volume.

The following examples illustrate how to use the SET UIC command.
Examples

$ SET UIC [370,10]

This command establishes your UIC as [370,10]. You can now read or modify
any files whose access is restricted to this UIC.
f:a

$ SET UIC [214,4]
$ SET DEFAULT [ANDERSON]

The SET UIC command sets your UIC to [214,4]; the SET DEFAULT
command sets the default directory name to [ANDERSON].
~

$ SET UIC [ELAINE]

This example sets the UIC to be that of the user named ELAINE. You can
optionally include the group name in the specification. For example, you
could set the UIC to [ET,ELAINE]. Note that, since the user name is unique
accross the system, the group name need not be included in the SET UIC
command description. However, the user's group name as well as the user
name will always be included in UIC displays.

4-12

Manipulating Files
4.2 Using DCL to Modify File Characteristics

4.2.6

Modifying Volume Characteristics
Use the DCL command SET VOLUME to modify the characteristics of one
or more mounted Files-11 disk volumes. In order to use this command, you
must have WRITE access to the index file on the volume. If you are not the
owner of the volume, you must have either a system UIC or the user privilege
SYSPRV. You must then specify the name of one or more mounted Files-11
volumes.
The examples that follow illustrate how the SET VOLUME command can be
used.
Examples

$ SET VOLUME/DATA_CHECK=(READ,WRITE) DBC5

This command requests that data checks be performed following all read and
write operations to DBCS.
~

$ SET VOLUME/LABEL= LICENSES DBC5:

This command encodes the label LICENSES on the volume DBCS. Note that,
if characters in labels are entered in lowercase, they are changed to uppercase
by the /LABEL qualifier.

4.3

Using DCL to Access Files
In addition to executing user programs that perform lfO operations on files
residing on disk and magnetic tape volumes, you can use DCL commands to
access disk and magnetic tape files for read and write operations.
Note that this section describes how to use DCL commands to access disk and
magnetic tape files at the file level (as opposed to the record level). Although
DCL does allow you to manipulate files at the record level, performance
considerations usually warrant the use of a conventional programming
language. DIGITAL recommends that you write programs using the VMS
Record Management Services (RMS) facilities that are specifically designed to
access files at the record level. You can write these programs in VAX MACRO
or in any of the higher-level languages supported by the VMS operating
system.
If you wish to access disk and magnetic tape files at the file level, you can
take advantage of DCL commands. As mentioned above, you cannot use
DCL commands to read or write files that are not in the standard formats
supported by the VMS operating system. If the file formats are not standard,
the volumes on which they reside must be mounted with the /FOREIGN
qualifier.

The following sections provide examples of the steps you can use to access
files on disk and magnetic tape volumes. In particular, these sections describe
how to manipulate disk and magnetic tape files (at the file level) for READ
and WRITE access.

4-13

Manipulating Files
4.3 Using DCL to Access Files

4.3.1

Accessing Disk Files for Read and Write Operations
You can access disk files for both read and write operations. The next
three sections show how to use DCL to access disk files for both types of
operations.
These sections contain examples of how to do the following:
•

Read files from a mounted disk volume

•

Write files to a disk volume that must first be allocated, initialized, and
mounted

•

Write files from a default directory to a volume that must first be
allocated, initialized, and mounted on a magnetic tape device

Although the examples used in the following sections show how to access
disk files on RK06/RK07 disk packs, they also apply to other devices.
4.3.1.1

Reading Files from a Disk Volume
To read the contents of a disk file, use the DCL command TYPE, which
displays the contents of a file on your terminal. To find the exact location of
the disk file you want to read, use the DCL command DIRECTORY.

For example, if you wish to read the contents of a file named HISFILE, which
is located somewhere in the directory [CHARLES] on a disk device whose
logical name is DISK$DOCUMENT, look for the exact location of HISFILE by
entering the following command:
$ DIRECTORY DISK$DOCUMENT: [CHARLES ... ]HISFILE.*

This command instructs the VMS operating system to search the entire
(CHARLES] directory, including all the subdirectories, for all file types and
version numbers of HISFILE. The following information will be displayed on
your terminal:
Directory DISK$DOCUMENT: [CHARLES.MEMO]
HISFILE.UPD;1
Total of 1 file.

This display informs you that there is only one version of HISFILE, that its
file type is UPD, and that it resides in the [CHARLES.MEMO] directory.
To read the contents of this file, enter the following command:
$ TYPE [CHARLES.MEMO]HISFILE.UPD

The contents of HISFILE will be displayed on your terminal.

4-14

Manipulating Files
4.3 Using DCL to Access Files

4.3.1.2

Writing Files to a Disk Volume
Before you can write files to a disk volume, the volume must be properly
prepared (see Chapter 3).

Because disks are random-access devices and since files must be listed in
directories, you must create a directory to contain your files on the disk
volume after you have initialized it, as in the following example:
$ CREATE/DIRECTORY DMA3: [PUBS]
$ DEFINE P DMA3: [PUBS]
$ COPY *. * P
$ COPY [PRIMER]*.* P
$COPY [COMMANDS]*.* P

The CREATE/DIRECTORY command creates a directory file named [PUBS]
on the device DMA3, and the DEFINE command defines the logical name
Pas DMA3:[PUBS]. The COPY command copies the highest versions of all
files in the current default directory and in the directories [PRIMER] and
[COMMANDS] to the newly created directory.

4.3.1.3

Writing Files from Disk Volumes to Magnetic Tape Volumes
The next example describes how to use DCL to write files from a default
directory on a disk volume to an ANSI-labeled magnetic tape volume. It
includes examples that show how to allocate, initialize, and use a magnetic
tape to copy a set of your disk files. The procedures are similar to those
for copying files from disk volumes to disk volumes. One main difference,
however, is that magnetic tapes are sequential-access devices and do not
have directories. (The characteristics of magnetic tape files are described more
thoroughly in the next section.)

First, allocate a drive as follows:
$ ALLOCATE MT: TAPE_DEVICE
%DCL-I-ALLOC _MARS$MTA2: allocated

This ALLOCATE command requests the allocation of a magnetic tape drive
whose name begins with MT. TAPE_DEVICE is a logical name, which in this
case refers to MTA2.
The system response indicates that unit 2 on controller A was available and is
now allocated to you. You can now physically load the magnetic tape on the
drive. Be sure the write ring on the magnetic tape is in place; if it is not, you
cannot write to the magnetic tape.
Next, initialize the magnetic tape by entering the following:
$ INITIALIZE TAPE_DEVICE: GMB001 _$ /PROTECTION=(GROUP:R,WORLD)

The INITIALIZE command specifies the logical name for the volume (TAPE_
DEVICE, which in this case refers to MTA2) and the volume label for the
magnetic tape volume (GMBOOl). The label can be no longer than six
characters. The /PROTECTION qualifier defines a protection code restricting
GROUP access to read and allowing no WORLD access. You can now enter
the MOUNT command to mount the volume and write files to it, as in the
following example:
$ MOUNT TAPE_DEVICE: GMB001
%MOUNT-I-MOUNTED, GMB001 mounted on _MTA2:
$ COPY *·* TAPE_DEVICE:

4-15

Manipulating Files
4.3 Using DCL to Access Files

The MOUNT command specifies the device name and volume label of the
volume on the device. The COPY command copies the highest versions of
all files in your default directory onto the magnetic tape. The file names, file
types, and version numbers of the output files default to the same file names,
file types, and version numbers as the input files.
If you enter the COPY command with the /LOG qualifier, the system will

send a message to the current SYS$0UTPUT device after each file has been
copied. You can also use the DIRECTORY command to verify that the files
were successfully copied.
$ DIRECTORY TAPE_DEVICE:

This DIRECTORY command lists the file names and file types of all files on
the magnetic tape.
When you have finished using the magnetic tape, dismount and deallocate it
as follows:
$ DISMOUNT TAPE_DEVICE:
$ DEALLOCATE TAPE_DEVICE:

If you do not dismount and deallocate the magnetic tape, the system does so

automatically when you log out.

4.3.2

Accessing Magnetic Tape Files for Read and Write Operations
When you request access to an ANSI-labeled volume or a file, the VMS
operating system checks at the volume and file level to ensure that your
process can access the volume or file. The level at which the system checks
access depends on the operation you request and the type of access the
operation requires.
When you access a volume or a file, the VMS software reads the volumeand file-header labels to determine whether access to the volume or file
is restricted. Which label is read depends on the operation requested. For
example, if you want to mount a volume, your process must have access to it.
Thus, the operating system reads the volume labels only.
This section describes file-level access for magnetic tapes. For more detailed
information on volume-level access and protection requirements for magnetic
tapes, see Chapter 2.
Your access to a particular file is determined by the protection that has
been set on that file. The expiration date field in the header can prevent
you from overwriting or appending to a file immediately preceding the one
in question. If the expiration date field has not been reached, the file has
not expired. You cannot overwrite an unexpired file unless you specify the
/OVERRIDE=EXPIRATION qualifier when you mount the volume.
The manner in which the file is accessed to perform an operation is called the
access type. READ or WRITE access, or both, are required.
Before accessing a particular file for a read or write operation, you may
want to search the magnetic tape volume for that file. The following section
describes how to use the DIRECTORY command to locate a file or group of
files on a magnetic tape volume.

4-16

Manipulating Files
4.3 Using DCL to Access Files

4.3.2.1

Locating ANSI-Labeled Magnetic Tape Files for READ or WRITE
Access
When you specify a VMS or ANSI file name for a file residing on magnetic
tape, the magnetic tape file system compares the file name with the file
header labels of each file until it finds a match in the file identifier field of the
file header labels.
If you supply a version number in the file name, it is compared with the

generation number and generation version-number fields in the first file
header label. If you do not specify a version number, the magnetic tape file
system neither defaults a version number nor checks the generation number
and generation version-number fields. The magnetic tape file system selects
the first file on the magnetic tape whose file name in the file identifier field
matches the specified file name.
Neither the directory nor the latest version number concept is supported by
the VMS operating system for magnetic tape volumes. VMS does not search
for or list the latest version of a specified file. The magnetic tape file system
cannot increment version numbers of files written to magnetic tape; therefore,
two or more files in the same volume set can have the same file name and
version number.
Because the magnetic tape file system selects the first matching file name
and version number (if specified), the position of the magnetic tape within
the volume set determines which file is returned on a search operation. A
search operation begins at the current position, so you may want to rewind
the volume set before accessing a file.
The search for a matching file and version number (if specified) continues at
the beginning of the header-label set of the next file. The search ends when
the magnetic tape is positioned at the file where the search began. If the
requested file is not found on the current volume, the remaining volumes in
the volume set are searched sequentially, according to their relative volume
numbers, until either a file name match occurs or the entire volume set is
searched.
If a file name match occurs, the internal file identification number is

constructed from the file section number, file sequence number, and relative
volume number. Although you can access a disk file by its file identification
number, you cannot access a magnetic tape file this way.
The VMS operating system does support the use of wildcard characters in
file specifications for magnetic tape volumes. However, there are certain
restrictions on using wildcard characters with magnetic tape files. Unlike files
on disk volumes, which support the asterisk ( • ), percent sign ( % ), ellipsis
( ... ), and minus sign (-)characters, magnetic tape volumes support only
the asterisk and percent-sign wildcard characters with VMS file names. ANSI
file names support only the asterisk wildcard character.
The asterisk wildcard character matches file specifications by field or portion
of a field. The percent sign wildcard character matches any character in a file
specification only by character positions within a field.
With VMS file names, you can specify the asterisk and the percent sign
anywhere in the file name and file type field to match file name specifications
by field or character position within a field. You cannot use the percent sign
in the version number field. Only the asterisk wildcard character can be used
in the version number field.

4-17

Manipulating Files
4.3 Using DCL to Access Files

With ANSI file names, a single asterisk in a field is the only wildcard
character that can be used. ANSI file names do support the special set of
ASCII "a" characters. Unlike VMS file names, which can consist of up to 39
characters each for the file name and file type, ANSI file names can have a
maximum of 17 characters in length. Whether you choose VMS file names or
ANSI file names depends on the type of applications you want to perform.
The examples that follow illustrate how to use wildcard characters in file
specifications to search for files on magnetic tape volumes. These examples
also show how the DIRECTORY command can be used in conjunction with
magnetic tapes. Note that the DIRECTORY command does not work the
same with magnetic tape files as with disk files.
Examples

$DIRECTORY MFA1:*.*;*

This command instructs VMS to search a volume set. Because asterisks are
used in the file specification and the asterisk is a valid wildcard character
for both ANSI and VMS file names, both VMS and ANSI file names will be
returned. Note that ANSI file names will be returned within quotation mark
characters.
~

$DIRECTORY MTA1:%*.*;*
$DIRECTORY MTAO:*.%*;*

In these two commands, the search can only match with VMS file names
because the percent sign is not valid for ANSI file names. In the second
command, the file type field must contain at least one character. Files with no
file type are not returned.
~

$DIRECTORY MTAO:*.;*

In this example, the DIRECTORY command instructs VMS to search for files
with ANSI file names, as well as VMS file names that have a null file type.

4.3.2.2

Reading Files on Magnetic Tape Volumes

When a magnetic tape file is accessed for a read operation, the magnetic tape
is positioned at the beginning of the file section after the file header labels.
You can use the DCL command TYPE to read a file or group of files on
the magnetic tape volume and to display the contents of the file on your
terminal. For example, if you want to read the contents of a file named
TESTFILE.DOC;l (which you know from your above directory searches is a
VMS file residing on the magnetic tape device MTAl), enter the following
command:
$ TYPE MTA1:TEST*.%*;*

You will then receive the following display on your terminal:
MTA1:TESTFILE.DOC;1
This is a test file.

When a file residing on a magnetic tape volume is accessed only for reading
the attributes in the header labels (rather than the data in the file section),
the magnetic tape file system returns the RMS attributes to your process. For
example, when you specify the DIRECTORY/FULL command for a volume,
file, or list of files, the magnetic tape file system selects the file identifiers from

4-18

Manipulating Files
4.3 Using DCL to Access Files

the header labels, returns the file attributes to your process, and positions the
magnetic tape after the header labels of the last file accessed.
A magnetic tape file opened for read access is closed either implicitly or
explicitly. The file is closed implicitly when the driver encounters a tape mark
while a file is being read. The magnetic tape file system then reads the trailer
labels, closes the file, and positions the magnetic tape at the next file.
The file is closed explicitly when you deaccess the file before all the data in
the file is read. The magnetic tape file system then closes the file without
reading the trailer labels, and the magnetic tape remains at the current
position.

4.3.2.3

Writing to Files on Magnetic Tape Volumes
When you use DCL to access an existing file for a write operation, one of
the following operations is actually being performed: append or update. The
difference between append and update write operations can be explained in
the following way:

•

Append Access
When a file is accessed for an append operation, the magnetic tape is
positioned at the EOF before the tape mark that precedes the trailer labels.
After the file is appended and closed, all files beyond the appended file
are lost. When the positioning is complete, the processing is handled as if
the file had been created as described in the section on file creation.

•

Update Access
When a file is accessed for an update operation, the magnetic tape is
positioned at the BOF section after the header labels. After the file is
written to and closed, all files beyond the updated file are lost. The
processing is handled as if the file had been created.

Note that you can update or append magnetic tape files only when the
header label contains a value of zero for the buffer offset length. For more
information on how to update and append magnetic tape files, see Chapter 5.
In addition to updating and appending files on a magnetic tape volume, you
can access a volume for a write operation by using the CREATE command to
write a new file to the magnetic tape volume. For example, you can enter the
following command string:
$ CREATE MTAO:MYFILE

You, can then write the contents of the file, without leaving the DCL
command level, before closing the file.
If you do not specify the /OVERRIDE=EXPIRATION qualifier, the magnetic
tape file system checks the expiration date field on the file before it allows
you to write to that file. When more than one file is to be overwritten,
the magnetic tape file system also checks the expiration date of the file
immediately following the file to be overwritten. For example, before you
append to a file, the magnetic tape file system checks the expiration dates
of both the file being appended and the file immediately following. If the
expiration date of either file has not been reached, the magnetic tape file
system does not allow you to append the file.

4-19

Manipulating Files
4.3 Using DCL to Access Files

When files are written to a magnetic tape volume, the magnetic tape file
system performs access checks, writes labels, and, if necessary, switches
volumes. If the new file will overwrite an existing file, the magnetic tape file
system checks the expiration date and accessibility fields of the existing file.
If overwriting is allowed, the magnetic tape file system overwrites the header
label set of the existing file, creates the file section, writes the trailer labels,
and writes two tape marks to denote the logical end-of-volume (EOV). All
files following the newly created file are lost.
To close a magnetic tape file that was opened for WRITE access, the magnetic
tape file system issues l:ommands to the driver to write the labels, which are
followed by a double tape mark that indicates the logical EOV.

4.4

Using Command Procedures to Access Foreign Volumes
The command procedures in this section allow you to create, read, or write
magnetic tape data in a simple, user-defined, foreign format.
$!
$!
FOREIGN.COM
$!
$! This is the master command procedure. It sets up the user account and
$! mounts the volume with the /FOREIGN qualifier. If the user wants to
$! read a foreign volume, the FORREAD.COM command procedure is called.
$! If the user wants to write a foreign volume the FORWRITE.COM
$! command procedure is called.
$!
verify_off_on = F$VERIFY ( 0 )
$
ON CONTROL_Y THEN GOTO clean_up
$
ON WARNING THEN GOTO clean_up
$
$

$!
$! If VOLPRO privilege is not set but the user account has SETPRV, VOLPRO is
$! set to allow the user to mount a new unformatted volume. If VOLPRO
$! privilege cannot be set, the user process is notified that the process
$! has insufficient privilege to write an unformatted volume. The user is also
$! asked whether to continue or exit the procedure.
$!
volpro_off _on = F$SETPRV ( "VOLPRO" )
$
IF F$PRIVILEGE ( "VOLPRO" ) THEN GOTO cont
$
WRITE SYS$0UTPUT "Insufficient Privilege to write an unformatted volume!"
$
INQUIRE/NOPUNC continue "Do you wish to continue (Y/N) ? "
$
IF .NOT. continue THEN GOTO clean_up
$
$ cont:
$
$!

$! Find out where the volume is mounted
$!
$ get_drive:
$
INQUIRE tape_drive "Tape drive"
$
IF tape_drive .EQS. "" THEN GOTO get_drive
$
tape_drive = tape_drive- 11 : 11 + 11 : "
$
IF .NOT. F$GETDVI (TAPE_DRIVE,"EXISTS")
$
THEN GOTO NOSUCHDEV
$
ASSIGN 'tape_drive' tape
$

4-20

Manipulating Files
4.4 Using Command Procedures to Access Foreign Volumes

$!
$! Try allocating and mounting the volume
$!
ALLOCATE tape:
$
MOUNT/NOASSIST/FOREIGN/OVERRIDE=(ACCESSIBILITY,EXPIRATION) tape:
$
$

$!
$! The user is asked whether a file will be read or written
$!
$

$ read_write:
$
INQUIRE/NOPUNC operation "Read or Write a file ? "
$
IF F$LOCATE ( operation, "READ" ) .EQ. 0 THEN GOTO read_op
$
IF F$LOCATE ( operation, "WRITE" ) .EQ. 0 THEN GOTO write_op
$
GOTO read_write
$
$ read_op:

©FORREAD
GOTO clean_up

$
$

$ write_op:

©FORWRITE

$ clean_up:
$

$!
$!
$!

Reset the user account the way it was before the command procedure began
SET NOON
DISMOUNT/NOUNLOAD tape:
DEALLOCATE tape:
DEASSIGN tape
volpro_off _on = F$SETPRV
verify_off_on = F$VERIFY

$
$
$

$
$
$
$

volpro_off _on )
verify_off_on )

$EXIT
$

$ NOSUCHDEV:
$
WRITE SYS$0UTPUT "No Such Device"
$
GOTO get_drive
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!
$!

FORWRITE.COM

Writes Data to a Foreign Volume

This command procedure writes data to a foreign volume.
The data format is as follows:
Each record is a block.
Records are variable length.
The first four characters of a record are digits that are
padded on the left with spaces. This sequence field starts at
1 and increases by 1 with each record.
The fifth character of a record is a comma.
The sixth through ninth characters are digits that are padded on the
left with spaces. This is a size field, which is the size of the data
field.
The tenth character of a record is a vertical bar.
The rest of the record is data.
Records are padded to be at least 20 characters long.

4-21

Manipulating Files
4.4 Using Command Procedures to Access Foreign Volumes

$!
$

seq_num = 0
spaces = "

! initialize the sequence number
"
! used to pad records less then 20 chars

$
OPEN/WRITE tape_file tape: ! open the output file
$ next_line:
$
$
$

$!
$!
$!

seq_num = seq_num + 1

! increment the sequence number

Prompt the user for the data
close the file and exit if -z is entered
READ/PROMPT= 11 Record # 'seq_num' : 11 /END_OF_FILE=end_of_input SYS$COMMAND user_data

$
$

$!
$!
$!
$
$
$

Find the size of the record and the number of pad characters needed
Note That a negative number of pad characters does not return any characters
data_size = F$LENGTH ( user_data )
pad_chars = 10 - data_size
IF pad_chars .LT. 0 THEN pad_chars = 0

$!
$!
$

Construct the output record using FAD
out_rec = F$FAO ( "!4UL,!4UL,!AS 11 , seq_num, data_size, user_data)
F$EXTRACT ( 1, pad_chars, spaces )

$
$
$

+ --

WRITE tape_file out_rec ! write the formatted output record
GOTO next_line

$ end_of_input:
$
CLOSE tape_f ile
$!
$!
$!
$!
$!
$!

FORREAD.COM

Reads Data from a Foreign Volume

This command procedure is called when data will be read. The procedure
reads data on a foreign volume. The data format is defined in
FORWRITE.COM command procedure.

$
$
$

seq_num = 0

! initialize the sequence number

$
OPEN/READ tape_f ile tape: ! open the output file
$ next_line:
$
$

seq_num = seq_num + 1

increment the sequence number

$
$
$
$
$
$
$

4-22

READ/END_OF_FILE=end_of_input tape_file in_rec
record_num = F$EXTRACT ( 0, 4, in_rec
-- 11 11 - - 11 11 - - 11 11
record_num = F$INTEGER ( record_num )
IF seq_num .NE. record_num THEN WRITE SYS$0UTPUT "Error possible data lost, record sequence broken!"

Manipulating Files
4.4 Using Command Procedures to Access Foreign Volumes

$!
$!
$!
$
$
$
$
$
$
$

Find the size of the data and extract the data
data_size = F$EXTRACT ( 5, 4, in_rec ) -- 11 11
data_size = F$INTEGER ( data_size )
data_rec = F$EXTRACT ( 10, data_size, in_rec

WRITE SYS$0UTPUT data_rec ! write the data output record
GOTO next_line

$ end_of_input:
$
CLOSE tape_f ile

4-23

Transferring Information

The VMS operating system provides various facilities for transferring
information contained on disk and magnetic tape media. In particular,
the DCL command COPY and the VMS Convert and Exchange Utilities can
be used to transfer disk and magnetic tape information.

5.1

Transferring Information Within and Across Operating Systems
In many cases, you will be able to transfer information without physically
transporting media. You may, however, find it necessary to transfer files
between systems that are not connected by a communications link. Under
these circumstances, you must be able to physically move your files from one
location to another. A convenient way to do this is to copy your files to a
portable volume, such as a magnetic tape reel or disk pack, and then carry
that volume to the location of the other system.
The VMS operating system supports the transfer of information contained
on disks and magnetic tapes both within the VMS system and across other
operating systems. It provides a number of facilities to assist you in both
types of information transfer. The two most frequently used facilities for
transferring information are the DCL command COPY and the VMS Exchange
Utility (EXCHANGE).
In many cases, you will find the COPY command and the Exchange Utility
sufficient for accomplishing information transfers. You may also find the VMS
Convert and Analyze/RMSJile Utilities useful for transferring information,
especially in foreign-volume or non-file-structured environments.
Under some circumstances, you will need to use the Backup Utility (BACKUP)
to transfer files. When using magnetic tape, for example, BACKUP is the only
means of transferring entire directory trees or files that are not sequentially
structured.
Each of the information transfer facilities provided by the VMS system, except
BACKUP, is described in the sections that follow. (See the VMS Backup Utility
Manual for information on the use of BACKUP.)

5.2

Using the COPY Command to Transfer Information
One way of transferring information on disk or magnetic tape media is to use
the DCL command COPY. The COPY command copies files from
•

Disk to disk

•

Disk to magnetic tape

•

Magnetic tape to disk

•

Magnetic tape to magnetic tape

The sections that follow describe how the COPY command is used with both
disk and magnetic tape files.

5-1

Transferring Information
5.2 Using the COPY Command to Transfer Information

5.2.1

Copying Files from Disk Volumes
This section describes how to use the COPY command to copy files from
disk volumes to other disk volumes and from disk volumes to magnetic tape
volumes.
The default format for files on disk volumes is called Files-11 Structure Level
2. You can also initialize disks in the Files-11 Structure Level 1 format, which
is the format used by other DIGITAL operating systems including RSX-llM,
RSX-llM-PLUS, RSX-110, and IAS.
In the following example, the COPY commands copy the highest versions of
all files in the current default directory and in the directories [PRIMER] and
[COMMANDS] to the directory [PUBS]:
$ DEFINE P DMA3: [PUBS]
$COPY*·* P:
$COPY [PRIMER]*.* P:
$COPY [COMMANDS]*.* P:

If you want to copy files from a disk directory - such as your default
directory - on a public disk volume to a private Files-11 disk volume, you
can also use the COPY command. Before copying these files, however, you
must set up (allocate, initialize, and mount) a disk device.

In the following example, assume that the disk device DMAS has been
allocated to your process and that a disk volume has been initialized and
mounted on that device. Also assume that you have a directory called
PRIVATE already created on that volume. Copy the highest version of all the
files in your default directory to the directory on that volume by entering the
following command:
$COPY *·*

DMA5: [PRIVATE]

You can also use the COPY command to copy files from a disk volume to a
magnetic tape volume. The procedure for copying files from disk volumes to
magnetic tape volumes is similar to those previously outlined for copying files
across disk volumes. Note that magnetic tapes are sequential-access devices
and do not have directories.
Again, you must set up (allocate, initialize, and mount) a magnetic tape
device before copying disk files to the magnetic tape volume. In the following
example, assume that MTA2 has been allocated to your process and that a
magnetic tape volume has been initialized and mounted on that device. You
can now use the COPY command to write files to the magnetic tape volume,
as in the following example:
$COPY *·*

MTA2:

In this case, the highest versions of all files in your default disk directory are
copied to the magnetic tape volume on MTA2. The file names, file types, and
version numbers of the output files default to the same file names, file types,
and version numbers as the input files.
If you enter the COPY command with the /LOG qualifier, the system sends
a message to the current SYS$0UTPUT device after each file has been
copied. To verify that the files were successfully copied, use the DIRECTORY
command. For example, the following command lists the file names and file
types of all files on the magnetic tape volume:
$DIRECTORY MTA2:

5-2

Transferring Information
5.2 Using the COPY Command to Transfer Information

When you copy files from disk to ANSI-labeled volumes, the following items
are not preserved:

5.2.2

•

Directory specifications

•

Individual file protection

•

User identification code (UIC)

•

Creation time (but the date is preserved)

•

Revision and backup dates and times

Copying Files from Magnetic Tape Volumes
This section describes how to use the COPY command to copy files from
magnetic tape.
The default format for files on magnetic tapes is the ANSI-labeled volume.
The VMS system supports sequential, relative, and indexed files on disks, but
only sequential files can be copied to ANSI-labeled volumes. The only valid
record formats are variable-length (ANSI D) and fixed-length (ANSI F). In the
example that follows, the ANSI file NEWINFO is copied from magnetic tape
volume to the file TESTING.DAT:
$ COPY MTA1:NEWINFO

TESTING.DAT

Although the VMS system supports stream and variable with fixed-length
control (VFC) records, it encodes these records in a variable-length format on
ANSI-labeled volumes. Non-VMS systems do not distinguish stream records
from VFC records; instead, they interpret both as variable-length records.
Therefore, neither stream nor VFC records should be created on volumes that
will be used for information interchange to a non-VMS system.
The full set of ASCII "a" characters are supported only for ANSI-labeled
volumes, not for disk volumes. Therefore, when you copy files with ANSI
file names from magnetic tape to disk, specify a standard VMS file name for
the output file name specification.
If you do not specify a VMS file name on output, your process receives the
following error message:
RMS-F-FNM, error in file name

This message indicates that the ANSI file name is not a valid file name
specification.
The entire set of Files-11 file names is supported for magnetic tapes. You
can copy a disk file with the following file name to a magnetic tape volume,
without having to modify the file name:
THIS-1S$A_VAXVMSLONG _FILE.LONG _EXT
You can also use the Exchange Utility to perform file transfers and format
conversions for DOS-11 magnetic tape volumes, Files-11 volumes, and RT11 block-addressable volumes. Refer to Section 5.4 of this manual or to the
VMS Exchange Utility Manual for more information.

5-3

Transferring Information
5.2 Using the COPY Command to Transfer Information

5.2.2.1

Continuing the Copy Command at End-of-Tape
When you are copying to or from a magnetic tape and that tape reaches the
end, the system suspends processing and sends a request to you to mount
the next magnetic tape in the volume set. An Operator Communication
Facility (OPCOM) message similar to the following may be displayed at your
terminal:

%%%%%%%%%%% OPCOM, 14-JUN-1985 15:23:31.78 %%%%%%%%%%%
request 3, from user PLAW
MOUNT new relative volume 2 (DWOQT2) on MTA1:

Note: Normally you do not see this message (messages may be sent only to the
operator's terminal that has been enabled for tape messages), and you
may not realize that another tape is needed to complete the read or write
operation.
See the Guide to Maintaining a VMS System for more information on OPCOM
messages.
If automatic volume switching is disabled or if the magnetic tape file system
cannot mount a given volume, you may need to mount a continuation
volume in a volume set. See Section 3.4.4.2 for information on mounting
a continuation volume. After loading the continuation volume on the drive
specified in the mount request, mount the volume by entering the REPLY
command with one of the following three qualifiers:

•

/TO=request_id [volume identifier] - Used for both read and write copy
operations. During a write operation, use the /TO qualifier if you want
the volume identifier specified in the mount request to be written on the
continuation volume.
For example, to respond to the mount request 3, mount volume DWOQT2
on drive MTAl and enter one of the following commands:
$ REPLY/T0=3
$ REPLY/T0=3 "DWOQT2"

The first REPLY command does not specify a volume identifier; the
second does.
•

/INITIALIZE_TAPE - Used for write operations if the volume identifier
on the continuation volume does not match the one specified in the
mount request. The file system reinitializes the tape and mounts
the volume with the new volume identifier. The magnetic tape file
system then performs access checks and initializes the volume as if the
INITIALIZE command had been specified. Any data on the tape prior
to specifying the /INITIALIZE_TAPE command is lost. Either of the
following REPLY commands is valid:
$ REPLY/INITIALIZE_TAPE=3
$ REPLY/INITIALIZE_TAPE=3 "DWOQT2"

The first command does not specify a volume identifier; the second does.
•

/BLANK_TAPE - Used to write to an unformatted volume. This
qualifier initializes the volume and requires the VOLPRO and OPER
privileges to avoid a runaway tape or timeout condition (see Chapter 3).
Either of the following· REPLY commands is valid:
$ REPLY/BLANK_TAPE=3
$ REPLY/BLANK_TAPE=3 "DWOQT2"

5-4

Transferring Information
5.2 Using the COPY Command to Transfer Information

The first command does not specify a volume identifier; the second does.
Specifying the volume identifier in either the MOUNT command or the
REPLY /TO command is essential during write operations because it ensures
that the correct volume is mounted on the drive and links the continuation
volume to the volume set.
You can omit the volume identifier with the REPLY /TO command under two
circumstances: (1) when reading from tape, the volume identifier is optional;
(2) during a write operation, you must omit the volume identifier to preserve
the accessibility code on a volume. If you initialize and mount a volume set
in which each volume has a unique accessibility character that you want to
maintain, avoid using the volume identifier since it causes the accessibility
character of the first volume in the set to overwrite the accessibility code on
the continuation volume. For example, to preserve the accessibility character,
enter the following command, where 3 is the request identification number:
$ REPLY/T0=3

Once it receives the REPLY command, the magnetic tape file system performs
checks on the continuation volume to ensure that it is the correct volume. As
long as it is the correct volume with proper access codes, the system mounts
the volume and reissues pending read or write requests to the continuation
volume. If the volume fails any of these access checks, the volume is not
mounted (or initialized and mounted, in the case of a blank tape).
The following examples illustrate ways of copying files to and from magnetic
tape volumes.
Examples

$ COPY /LOG MTA1: "%&*?!SKI! '""' SEASON. DAT
%COPY-S-COPIED, MTA1 : [] "%1h? ! SKI! """ . ; 1
copied to WRKD: [MANUAL]SEASON.DAT;1 (120 records)

Since the /LOG qualifier was specified, the system returns a message that
confirms the file was copied as specified and informs you how many records
were copied. The ANSI file %&•?!SKI!#"(# means space) is copied to the file
SEASON.DAT on the default disk and directory WRKD:[MANUAL]. The file
could not have been copied to disk unless the new file name was specified.
The VMS software provided defaults for segments of the file specification that
were not specified.
~

$ COPY /LOG FORTAP. DAT MTA1: "%&*?!SKI! 1111 11
%COPY-S-COPIED, WRKD: [MANUAL]FORTAP.DAT;1
copied to MTA1: 0"%&*?!SKI! """· ;O (120 records)

In this command an ANSI file name was specified as the output file
specification. Note that the trailing space in the file name %&•?!SKI!##"#
(where# means space) is truncated.
~

$COPY/LOG VAXVMS_LONG$FILE_NAME.LONG_EXT MTA1:
%COPY-S-COPIED, WRKD: [MANUAL]VAXVMS_LONG$FILE_NAME_EXT;1
copied to MTA1:VAXVMS_LONG$FILE_NAME.LONG_EXT;1 (80 records)

In this example, a VMS long file name with a long extension is copied to the
volume MTAl with the same file name and type that had been on the disk
volume.

5-5

Transferring Information
5.2 Using the COPY Command to Transfer Information

$ COPY %% . JOU;* MTA1: *. *
%COPY-S-COPIED, WRKD: [MANUAL]C6.JOU;1 copied to MTA1: []C6.JOU;1 (4 records)

In this example, all files with a two-character file name and a file type of JOU
are copied to the volume MTAl with the same file name and type as they
had on the disk volume. Version numbers are preserved.
~

$ COPY MTAO: *. * *
%COPY-S-COPIED, MTAO: []TASTETEST.DAT;1
copied to WRKD: [FOOD]TASTETEST.DAT;1 (249 records)
%COPY-S-COPIED, MTAO: []ALLAT;1 copied to WRKD: [FOOD]ALALL;1 (48 rcords)
%COPY-S-NEWFILES, 2 files created

In this example, neither file on the tape volume had an ANSI file name.
Therefore, both files were copied to the disk volume.
~

$ COPY MTA1: *. * [EX]
%COPY-S-COPIED, MTA1: [] .DAT;1 copied to WRKD: [EX]TEST.DAT21 records)
%COPY-E-OPENOUT, error opening WRKD: [EX] 11 %&*()!SKI! 111111 • ;1 as output
-RMS-F-FNM, error in file name
%COPY-W-NOTCOPIED, MTA1: [] 11 %&* ()!SKI! 1111 " . ; 1 not copied
%COPY-E-OPENOUT, error opening WRKD: [EX] 11 SANFRAN%%% 111111 • ;1 as output
-RMS-F-FNM, error in file name
%COPY-W-NOTCOPIED, MTA1: [] 11 SANFRAN%%% 111111 . ; 1 not copied
%COPY-S-COPIED, MTA1: []VAXVMS_LONG$FILE_NAME.LONG_EXT;1
copied to WRKD$: [EX]VAXVMS_LONG$FILE_NAME.LONG_EXT;1 (80 records)
%COPY-S-COPIED, MTA1: []C6.JOU;1 copied to WRKD: [EX]C6.JOU;1 (4 records)
%COPY-S-NEWFILES, 2 files created

The COPY command string specifies that all files on the volume mounted
on drive MTAl should be copied to the current default disk and directory
WRKD:[EX]. However, files with ANSI file names are not copied; VMS
returns an error message to the process.
The following sections provide guidelines for interchanging volumes.

5.2.3

Copying Files to and from Non-File-Structured Volumes
The VMS operating system supports the transfer of files between filestructured and non-file-structured volumes. You can use the COPY command
to transfer files in the following ways:
•

From file-structured volumes to non-file-structured volumes

•

From non-file-structured volumes to file-structured volumes

The next two sections contain examples of each type of transfer.
5.2.3.1

Copying Files to a Non-File-Structured Volume

This section contains a procedure for copying files from a file-structured
volume to a non-file-structured, or foreign volume.
The following procedure copies three files from an ANSI-labeled volume to a
foreign volume.

Mount the volumes involved in the copy operation as follows:
$MOUNT MTA1: FRESKI
%MOUNT-I-MOUNTED, FRESKI mounted on _MTA1:
$ MOUNT/FOREIGN MTAO:
%MOUNT-I-MOUNTED, mounted on _MTAO:

5-6

Transferring Information
5.2 Using the COPY Command to Transfer Information

Enter the COPY command string, including the full device and file
name specifications in the input specification, but specify the device
name only in the output specification. File names are specified on input
because the volume from which files will be copied is ANSI-labeled and
file-structured. However, only the device name is specified on output
because the volume to which the files will be copied is foreign and is not
file-structured.
$COPY/LOG MTA1:PROG1.EXE, PROG2.EXE, PROG3.EXE MTAO:
%COPY-S-COPIED, MTA1: []PROG1.EXE;1 copied to MTAO: (92 records)
%COPY-S-COPIED, MTA1: []PROG2.EXE;6 copied to MTAO: (70 records)
%COPY-S-COPIED, MTA1: []PROG3.EXE;2 copied to MTAO: (77 records)
%COPY-S-NEWFILES, 3 files created

Because no version numbers were specified for the files copied from the
ANSI-labeled magnetic tape volume, the first version of each specified file the
MTAACP finds on the ANSI-labeled volume will be the version of the file
that is copied to the foreign volume.
When you use the /LOG qualifier with the COPY command, the system
informs you which files are copied and tallies the number of records copied
and the number of files created.
When you copy files as shown in this example, the structure of the resulting
magnetic tape is referred to as unblocked, non-file-structured. Each file
record becomes a physical record on the magnetic tape. Each file boundary is
indicated on the magnetic tape by a single tape mark. Two consecutive tape
marks indicate end of volume. No label, file name, or attribute information is
present.

5.2.3.2

Copying Files from a Non-File-Structured Volume

This section contains a procedure for copying data segments from a nonfile-structured, or foreign, volume to a file-structured ANSI-labeled volume.
Note that you must specify a COPY command for each segment of data that
you copy from a foreign, or non-file-structured, volume to a file-structured
volume.

Mount the volumes as follows:
$ MOUNT/NOLABEL MTA1: II II COLD:
%MOUNT-I-MOUNTED, mounted on _MTA1:
$ MOUNT MTAO: FEVER SEASON:
%MOUNT-I-MOUNTED, FEVER mounted on _MTAO:

Enter a COPY command for each segment on the foreign volume to
be copied to files on the file-structured volume. Because the volume to
which data segments are copied is file-structured, you must specify a file
name in the output file specification.

5-7

Transferring Information
5.2 Using the COPY Command to Transfer Information

$COPY/LOG COLD: SEASON:FILE1.DAT
%COPY-S-COPIED, MTA1: copied to SEASON:FILE1.DAT;1 (92 records)
$COPY/LOG COLD: SEASON:FILE2.DAT
%COPY-S-COPIED, MTA1: copied to SEASON:FILE2.DAT;1 (62 records)
$COPY/LOG COLD: SEASON:FILE3.DAT
%COPY-S-COPIED, MTA1: copied to SEASON:FILE3.DAT;1 (23 records)
$COPY/LOG COLD: SEASON:FILE4.DAT
%COPY-S-COPIED, MTA1: copied to SEASON:FILE4.DAT;1 (48 records)
$COPY/LOG COLD: SEASON:FILE5.DAT
%COPY-S-COPIED, MTA1: copied to SEASON:FILE5.DAT;1 (37 records)
$COPY/LOG COLD: SEASON:FILE6.DAT
%COPY-S-COPIED, MTA1: copied to SEASON:FILE6.DAT;1 (10 records)

Since the /LOG qualifier was used with the COPY command, VMS informs
you that the files you specified were copied to the appropriate device and that
tallies the number of records transferred.

5.3

Using the Convert Utility to Transfer Information
This section describes how to use the VMS Convert Utility (CONVERT)
to transfer information to non-file-structured, or foreign, volume. It also
describes how the VMS Analyze/RMSJile Utility (ANALYZE/RMSJILE),
which is useful in determining record size, is used in conjunction with
CONVERT.
There may be cases where you will be unable to transfer information to a
non-file-structured, or foreign, volume by using the COPY command. For
example, files containing records smaller than 14 bytes cannot be copied
successfully to a foreign volume with the COPY command. However, they
can be transferred by using CONVERT.
CONVERT allows you to pad and extend the record size to make it suitable
for a foreign volume. The following procedure illustrates how to use the
Convert Utility:

Mount both volumes. Specify the /RECORDSIZE and /BLOCKSIZE
qualifiers in addition to either the /NOLABEL or /FOREIGN qualifier
when you mount the foreign volume.
$ MOUNT/FOREIGN/RECORDSIZE=80/BLOCKSIZE=2400 MTA1:
%MOUNT-I-MOUNTED, mounted on _MTA1:
$ MOUNT MTAO: LATER TODAY
%MOUNT-I-MOUNTED, LATER mounted on _MTAO:

The VMS operating system informs you that the foreign volume is
mounted on drive MTAl and that the target volume is mounted on
MTAO. The /RECORDSIZE and /BLOCKSIZE qualifiers specify the tape
is to be written as 80-byte records blocked in 2400-byte blocks.

Check the size of the largest record within a file. To do so, use the
Analyze/RMSJile Utility as shown in the following example:
$ ANALYZE/RMS_FILE/STATISTICS TODAY:TICKET.DAT
RMS File Statistics
TODAY: []TICKET.DAT;3

5-8

14-JUN-1988 21:33:20.07

Transferring Information
5.3 Using the Convert Utility to Transfer Information

FILE HEADER
File Spec: TODAY: []TICKET.DAT;3
File ID: (1,1,1)
Owner UIC: [012,141]
Protection: System:RWED, Owner:RWED, Group:WE, World:WE
Creation Date:
5-APR-1988 14:20:04.06
Revision Date:
17-NOV-1988 09:10:05.19, Number: 3
Expiration Date: none specified
Backup Date:
none posted
Contiguity Options: none
Performance Options: none
Reliability Options: none
Journaling Enabled: none
RMS FILE ATTRIBUTES
File Organization: sequential
Record Format: variable
Record Attributes:
carriage-return
Maximum Record Size: 255
Longest Record: 77
Blocks Allocated: 0, Default Extend Size: 0
End-of-File VBN: 1, Offset: %X'OOOO'
File Monitoring: disabled
Global Buffer Count: 0
The analysis uncovered NO errors.
ANALYZE/RMS_FILE/STATISTICS TODAY:TICKET.DAT

Extend the size of records smaller than 14 bytes to that specified in
the MOUNT command and ensure that the record size you specify is
sufficient. To do so, enter the following commands:
$ CDNVERT/PAD/FDL=SYS$INPUT
$_Input: TDDAY:TICKET.DAT
$_Output: MTA1:
RECORD
SIZE 80
FORMAT FIX 15 EXIT
$

Entering the CONVERT command string, along with the input and output
parameters, pads and extends the size of records when copying them
from the ANSI-labeled volume mounted on MTAO to the foreign volume
mounted on MTAl. The CONVERT command and qualifiers can pad
short records to correspond to the record size specified by the MOUNT
command in the first step. After you enter the command line, CONVERT
prompts you for input and output parameters. At the $-1nput: prompt,
supply the specification of the file containing the records that were too
short. At the $_Output: prompt, specify only the physical or logical
device name of the foreign volume. Pressing CTRL/Z terminates the
file description and causes CONVERT to run. To verify that the file was
copied to the foreign volume, you can rewind the foreign volume and
type the volume as shown in the steps below.

To rewind a foreign volume, enter the following SET MAGTAPE
/REWIND command string:
$ SET MAGTAPE/REWIND MTA1:
$

5-9

Transferring Information
5.3 Using the Convert Utility to Transfer Information

To verify the contents of a file, enter the TYPE command as follows:
$ TYPE MTA1:

This is a test file.
Some records contain less than 14 bytes.
This file was copied to a foreign volume with the
RMS Convert Utility.
Any record less than 80 bytes was extended and padded to
80 bytes.

The TYPE command types the first data segment on the volume. If you
copy multiple files to a foreign volume with the RMS Convert Utility,
each file is copied to the volume in a separate data segment. Therefore,
you must enter a TYPE command for each data segment copied to the
volume until you reach the segment that you want to verify.
This example produces what is referred to as a blocked non-file-structured
volume. Each record of the input file is placed into an 80-byte area of a
2400-byte tape block. Tape marks are used to delimit files, as in the previous
example.

5.4

Using the Exchange Utility to Transfer Information
The VMS system provides a utility called Exchange, which enables you to
read to or write from disk and magnetic tape media being exchanged with
DIGITAL-supported, non-VMS operating systems. With the VMS Exchange
Utility (EXCHANGE), you can manipulate mass-storage volumes written in
formats other than those normally recognized by VMS. You can also use
EXCHANGE to manipulate Files-11 files that are images of foreign volumes.
You can use EXCHANGE to transfer files between foreign volumes and VMS
file-structured volumes. You can also use EXCHANGB to perform volumespecific initialization and manipulation functions on the foreign volumes. The
Exchange Utility enables you to convert the format of the files, as appropriate,
when transferring files between volumes with different structures.
The Exchange Utility can perform file transfers and format conversions for the
following:
•

DOS-11 magnetic tape volumes

•

Files-11 volumes

•

RT-11 block-addressable volumes

In addition to transferring files, the Exchange Utility allows you to mount
and dismount foreign volumes, initialize foreign volumes, list directories
of volumes, delete files from block-addressable volumes, and locate bad
blocks on the volume. For further information on how to use EXCHANGE to
accomplish these tasks, see the VMS Exchange Utility Manual.

5-10

Transferring Information
5.4 Using the Exchange Utility to Transfer Information

5.4.1

Invoking and Terminating the Exchange Utility
To invoke EXCHANGE, enter the following command in response to the DCL
prompt:
$ EXCHANGE
EXCHANGE>

When you receive the EXCHANGE prompt (EXCHANGE> ), you are in
the Exchange Utility. Once you are in this utility, you can enter any of the
command strings supported for EXCHANGE. For example:
EXCHANGE> DIRECTORY MFAO:/VOLUME=DOS11/FULL

This command lists all the files on the DOS-11 magnetic tape mounted on
MFAO. In this case, the magnetic tape is rewound before the files are listed.
The following example illustrates the use of the MOUNT command within
the Exchange Utility:
EXCHANGE> MOUNT DMA1:
%EXCHANGE-I-WRITELOCK, volume is write-locked
%EXCHANGE-I-MOUNTED, volume DMA1: mounted

This command mounts the foreign volume that is loaded in the RK07 device
DMAl, making the volume available for subsequent commands. In this case,
EXCHANGE recognizes that the volume itself is write-locked, and displays
the message.
See the VMS Exchange Utility Manual for a complete list of all the commands,
qualifiers, and parameters that are supported for EXCHANGE.
To exit from EXCHANGE and return to DCL level, use the EXCHANGE
command EXIT or CTRL/Z.

5.4.2

Using EXCHANGE at DCL Command Level
In addition to using EXCHANGE interactively as a utility, you can use
EXCHANGE as a DCL command. To do this, append a command string to
the DCL command EXCHANGE as follows:
$EXCHANGE DIRECTORY DMA1:/VOLUME_FORMAT=RT11

This DCL command lists the directory of the RT-11 volume mounted (
/FOREIGN) on DMAl. At DCL level, EXCHANGE executes the single
command and returns to the DCL prompt.
At DCL level, you can process only one command at a time. Some tasks
for which EXCHANGE was designed, however, require more than one
EXCHANGE command. For example, the use of virtual devices requires
multiple EXCHANGE commands.
Tasks requiring more than one EXCHANGE command cannot be performed
at DCL level. You can, however, design a command procedure to execute
more than one EXCHANGE command for a particular task. In that case, you
could execute the command procedure without leaving the DCL command
level. For further details on how to construct command procedures using
EXCHANGE, see Section 5.5.

5-11

Transferring Information
5.5 Using Command Procedures to Transfer Information

5.5

Using Command Procedures to Transfer Information
You can design command procedures to facilitate routine transferring of
information on disk and magnetic tape media.
Two examples of command procedures are included in this section. The first
example is designed to transfer information by way of the COPY facility. The
second example employs the Exchange Utility to transfer the information.

5.5.1

Using a Command Procedure to Copy Files
The sample command procedure in this section can be used for a variety
of purposes. This procedure can copy from disk to similar disk, from disk
to dissimilar disk, and from magnetic tape to magnetic tape. Note that the
command procedure mounts the volume as non-file-structured.
If you are using magnetic tape media, this command procedure will not work
for multi-reel magnetic tape volume sets. Magnetic tape to magnetic tape
transfer is supported for single volumes only. The magnetic tape to magnetic
tape copy is accomplished using the asterisk ( *) wildcard character.

The sample command procedure is as follows:
$ vol_priv = f$setprv("volpro")
$ Type sys$input
$ on control_y then goto cleanup
$ on warning then goto cleanup
$ !

$ get_source:
$
write sys$output "Enter drive holding the write-locked master."
$
inquire source " [CS1$DRBO: , DBxx: , DDxx: , DJxx: , DLxx: , DMxx: , $
DQxx:, DRxx:, DUxx:, DYxx:, MFxx:, MTxx:, MUxx: ,] "
$
if source .eqs. "" then goto get_source
$
source= source -":"+":"
$

$ get_target:
$
inquire target "Enter drive holding the write-enabled target."
$
i f target .eqs. "" then goto get_target
$
target = target -": "+":"
$
kit_type := 'f$extract(0,1,source)
$
if f$locate("CS",source) .eq. f$length(source) .and. f$locate("CS",target) .eq. f$length(target) then goto prepare
$
*Note* -- This section checks to see if the console is configured
$
into the system.
$
If it does not exist, SYSGEN will be run to configure it in
$ !
$ !

$ connect_console:
$
! (NOTE* For 750,730 media copying CONSOLE must be configured)
$
if f$getdvi("CS:1","exists") then goto prepare
$
set noon
$
proc_priv = f$setprv("cmkrnl,cmexec")
$
run sys$system:sysgen
connect console
proc_priv = f$setprv(proc_priv)
$
set on
$

5-12

Transferring Information
5.5 Using Command Procedures to Transfer Information

$ !

$ prepare:
$
allocate 'source'
$
inquire start "Ready source volume ''source' for mounting and
$
press return"
$

$ begin:
$
allocate 'target'
$
mount/foreign 'source'
$
inquire start "Ready target volume ''target' for initialization and
$
press return"
$
volume_lbl = f$getdvi(source,"VOLNAM")
$
i f (volume_lbl . eqs. '"') then volume_lbl
"console"
$
init 'target' 'volume_lbl'
$
If (kit_type .eqs. "M") then goto tape_copy
$
mount/foreign 'target'
$
backup/physical/verify 'source' 'target'
$
goto copy_done
$

$ tape_copy:
$
mount/over:id 'target'
$
copy 'source'*·* 'target'*/log
$
$ copy_done:
dismount 'target'
$
deallocate 'target'
$
$
write sys$output "Copy is complete"
$
dismount/nounload 'source'

$
$
$
$
$ !

inquire answer "Do you want to make another copy of the Source volume?"
if .not. answer then goto new_source
write sys$output "Please place volume in the target device ''target'." "
goto begin

$ new_source:
deallocate 'source'
$
inquire answer "Do you want to make a copy using a new Source device?
$
if answer then goto get_source
$
goto finish
$
$

$ cleanup:
$
i f f$getdvi(target,"mnt") then
$
i f f$getdvi(source,"mnt") then

dismount 'target'
dismount 'source'

$ finish:
$
vol_priv = f$setprv(vol_priv)
$
if f$getdvi (target, "all") then deallocate 'target'
$
i f f$getdvi(source, 11 all 11 ) then deallocate 'source'
$
exit

5.5.2

Using a Command Procedure to Exchange Information
The following command procedure is designed to exchange files between the
console device and the current directory on disk. The files to be copied are
assumed to be in standard format as determined by file type.

5-13

Transferring Information
5.5 Using Command Procedures to Transfer Information

$ WRITE SYS$0UTPUT " Command file to copy files to/from the system"
$WRITE SYS$0UTPUT" console storage medium and the current directory."
$ WRITE SYS$0UTPUT II II
$ INQUIRE MOUNT "Is system console storage medium mounted (Y/N)?"
$ IF MOUNT THEN GOTO MOUNTED
$ WRITE SYS$0UTPUT "Please place the system console medium in the console drive"
$ INQUIRE MOUNT "and type ~ when ready"
$ RUN SYS$SYSTEM:SYSGEN
CONNECT CONSOLE
$ MOUNT/SYSTEM/FOREIGN CSA1: "VAX console"
$ !

$ MOUNTED:
$ INQUIRE DIR "Copy from console medium (Y/N)?"
$ IF DIR THEN GOTO FROMCON
$ INQUIRE SOURCE "Enter file name(s)"
$ IF SOURCE .EQS. "" THEN GOTO EXIT
$ EXCHANGE COPY /LOG 'SOURCE' CSA1:
$ GOTO EXIT
$ !

$ FROMCON:
$ INQUIRE SOURCE "Enter console file name"
$ IF SOURCE .EQS. "" THEN GOTO EXIT
$ EXCHANGE COPY /LOG CSA1: 'SOURCE' *
$ EXIT:
$ DISMOUNT CSA1:
$ MOUNT/SYSTEM/FOREIGN/NOWRITE CSA1: "VAX console"

5-14

VMS Disk Files and Volumes

A.1

Files-11 Disk Structure
The VMS system recognizes two disk file structures: Files-11 On-Disk
Structure Level 1 and Files-11 On-Disk Structure Level 2. Files-11 On-Disk
Structure Level 2 is the default disk structure of the VMS system, and Files11 On-Disk Structure Level 1 is a structure used by DIGITAL's RSX-llM,
RSX-llD, RSX-11M-PLUS, and IAS operating systems.
Nine files control the structure of a Files-11 On-Disk Structure Level 2
volume. Only five of these files are used for a Files-11 On-Disk Structure
Level 1 volume. Table A-1 identifies all nine files, which are referred to as
reserved files, and indicates to which Files-11 On-Disk Structure Level they
pertain.
Table A-1

VMS Reserved Files

Reserved File

File Name

Index file

INDEXF.SYS;1

Storage bit map file

BITMAP.SYS; 1

Bad block file

BADBLK.SYS; 1

Master file directory

000000.DIR; 1

Core image file

CORIMG.SYS; 1

Volume set list file

VOLSET.SYS;1

Continuation file

CONTIN.SYS; 1

Backup log file

BACKUP.SYS; 1

Pending bad block

BADLOG.SYS;1

Structure
Level 1

x
x
x
x
x

Structure Level 2

x
x
x
x
x
x
x
x
x

All the files listed in Table A-1 are listed in the master file directory (MFD),
[000000].

A.1.1

Index File
Every Files-11 volume has an index file, which is created when the volume
is initialized. This index file identifies the volume to the operating system as
a Files-11 structure and contains the access data for all files on the volume.
The index file, which is listed in the master file directory as INDEXF.SYS;l,
contains the following information:
•

Bootstrap block - The volume's bootstrap block is virtual block number
1 of the index file. If the volume is a system volume, this block contains
a bootstrap program that loads the operating system into memory. If
the volume is not a system volume, this block contains a program that
displays the message that the volume is not the system device but a
device that contains users' files only.
A-1

VMS Disk Files and Volumes
A.1 Files-11 Disk Structure

A.1.2

•

Home block - The home block establishes the specific identity of the
volume, providing such information as the volume name and protection,
the maximum number of files allowed on the volume, and the volume
ownership information. The home block is virtual block number 2 of the
index file.

•

Alternate home block - The alternate home block is a copy of the home
block. It permits the volume to be used even if the primary home block
is destroyed.

•

Alternate index file header - The alternate index file header permits
recovery of data on the volume if the primary index file header becomes
damaged.

•

Index file bit map - The index file bit map controls the allocation of
file headers and thus the number of files on the volume. The bit map
contains a bit for each file header allowed on the volume. If the value of
a bit for a given file header is 0, a file can be created with this file header.
If the value is 1, the file header is already in use.

•

File headers - The largest part of the index file is made up of file
headers. Each file on the volume has a file header, which describes
such properties of the file as file ownership, creation date and time, file
protection, and location of the data in the file. The file header contains all
the information needed for gaining access to the file.

Storage Bit Map File
The storage bit map file controls the available space on a volume; this file
is listed in the master file directory as BITMAP.SYS;l. It contains a storage
control block, which consists of summary information intended to optimize
the Files-11 space allocation, and the bit map itself, which lists the availability
of individual blocks.

A.1.3

Bad Block File
The bad block file, which is listed in the master file directory as
BADBLK.SYS;l, contains all the bad blocks on the volume. The system
detects bad disk blocks dynamically and prevents their reuse once the files to
which they are allocated have been deleted.

A.1.4

Master File Directory
The master file directory (MFD) itself is listed in the MFD as 000000.DIR;l.
The MFD, which is the root of the volume's directory structure, lists the
reserved files that control the volume structure and may list both users' files
and users' file directories. Usually, however, the MFD is used to list the
reserved files and users' file directories; users seldom enter files in the MFD,
even on private volumes. In fact, on a private volume, it is most convenient
for a user to create a directory that has the same name as the user's default
directory on a system disk. For an explanation of users' file directories and
file specifications, see the VMS DCL Concepts Manual.
When the VMS Backup Utility (BACKUP) creates sequential disk save sets, it
stores the save set file in the MFD.

A-2

VMS Disk Files and Volumes
A.1 Files-11 Disk Structure

A.1.5

Core Image File
The core image file is listed in the MFO as CORIMG.SYS;l. It is not
supported by the VMS operating system.

A.1 .6

Volume Set List File
The volume set list file is listed in the MFO as VOLSET.SYS;l. This file is
used only on relative volume 1 of a volume set. The file contains a list of the
labels of all the volumes in the set and the name of the volume set.

A.1 . 7

Continuation File
The continuation file is listed in the MFO as CONTIN.SYS;l. This file is used
as the extension file identifier when a file crosses from one volume to another
volume of a loosely coupled volume set. This file is used for all but the first
volume of a sequential disk save set.

A.1.8

Backup Log File
The backup log file is listed in the MFO as BACKUP.SYS;l. This file is
reserved for future use.

A.1.9

Pending Bad Block Log File
The pending bad block log file is listed in the MFO as BAOLOG.SYS;l. This
file contains a list of suspected bad blocks on the volume that are not listed in
the bad block file.

A.1.10 Files-11 On-Disk Structure Level 1 Versus Structure Level 2
For reasons of performance and reliability, Files-11 On-Disk Structure Level
2, a compatible superset of Structure Level l, is the preferred disk structure on
the VMS system. At volume initialization time (see the INITIALIZE command
in the VMS DCL Dictionary), Structure Level 2 is the default. Structure Level 1
should be specified only for volumes that must be transportable to RSX-1 lM,
RSX-110, RSX-11M-PLUS, and IAS systems, as these systems support only
that structure level. Additionally, you may be required to handle Structure
Level 1 volumes transported to VMS from one of the above systems.
Where Structure Level 1 volumes are in use on the system, you should bear
in mind the following limitations on them:
•

Directories - No hierarchies of directories and subdirectories, and no
ordering of directory entries (that is, the file names) in any way. RSXllM, RSX-110, RSX-llM-PLUS, and IAS systems do not support
subdirectories and alphabetical directory entries.

•

Disk quotas -

•

Multivolume files and volume sets -

•

Placement control -

Not supported.
Not supported.

Not supported.

A-3

VMS Disk Files and Volumes
A.1 Files-11 Disk Structure

•

Caches - No caching of file header blocks, file identification slots, or
extent entries.

•

System disk -

•

VAXcluster access -

•

Clustered allocation -

Not supported.

•

Backup home block -

Not supported.

•

Protection code E - Means extend for the RSX-1 lM operating system
but is ignored by VMS.

•

File versions -

•

Enhanced protection features (for example, Access Control Lists) supported.

•

Long file names -

Not supported.

•

RMS journaling -

Not supported.

•

RMS execution statistics monitoring -

Cannot be a Structure Level 1 volume.
Local access only; cannot be shared across a cluster.

Limited to 32,767; version limits are not supported.
not

Not supported.

Future enhancements to VMS software will be based primarily on Structure
Level 2, so that further restrictions on Structure Level 1 volumes might be
incurred.

A-4

VMS ANSI-Labeled Magnetic Tape

This appendix briefly describes ANSI labels, data, and record formats
supported by the VMS operating system. It also describes support for the
various ANSI labels on VMS. Note, however, that the VMS software also
supports the ISO standard. For a complete description of these labels, please
refer to the ANSI X3.27-1978 or ISO 1001-1979 standard.

B.1

Logical Format of ANSI-Labeled Volumes
The format of VMS ANSI-labeled magnetic tape volumes is based on Level
3 of the ANSI standard for magnetic tape labels and file structure for
information interchange. This standard specifies the format, content, and
sequence of volume labels, file labels, and file structures. According to this
standard, volumes are written and read on 9-track magnetic tape drives only.
The contents of labels must conform to prescribed data and record formats.
All labels must consist of ASCII "a" characters.
The VMS ANSI-labeled format allows you to write binary data in the file
sections (see Figure B-1) of files. However, if you plan to use such files for
information interchange across systems, make sure that the recipient system
can read the binary data.

B.2

VMS Magnetic Tape Ancillary Control Process (MTAACP)
The VMS magnetic tape ancillary control process (MTAACP) is the internal
software process of the operating system that interprets the logical format
of VMS ANSI-labeled volumes. Transparent to your process, the MTAACP
process reads, writes, and interprets VMS ANSI labels before passing this
information to VMS Record Management Services (RMS) and Queue I/O
($QIO) system services. These services in turn read, write, and interpret the
record format of the data written in the file section.

B.3

Basic Components of the VMS ANSI-Labeled Format
The format of VMS ANSI-labeled magnetic tape consists of four basic
components:
•

Beginning-of-tape (BOT) and end-of-tape (EOT) markers

•

Tape marks

•

File sections

•

Volume, header, and trailer labels

Figure B-1 displays the arrangement and function of these components.

B-1

VMS ANSI-Labeled Magnetic Tape
B.3 Basic Components of the VMS ANSI-Labeled Format

Figure B-1

Basic Layout of a VMS ANSI-Labeled Volume

Beginning-of-Tape
Marker (BOT)
Volume Label
(VOL1)
File Header Labels
(HDR1, HDR2, HDR3)
Tape Mark (TM)

File Section

Tape Mark (TM)

Marks beginning of writeable area on a volume

Identifies the volume

Describes and delimits each file

Separates header labels from file section

Contains user data. Data in volumes interchanged to
non-VAX/VMS systems must be ASCII "a" characters.
Data in volumes interchanged to VAX/VMS systems can
be in binary form.

Separates file section from trailer labels

File Trailer Labels
(EOF1, EOF2, EOF3,
EOV1, EOV2, EOV3)

Describes and delimits files. When a volume is continued, EOV labels are written instead of EOF labels. EOF3
or EOV3 labels are written only when a HDR3 label is
written.

Tape Mark

Indicates the logical end-of-volume. Two consecutive
tape marks are always written after the trailer labels of
the last file on a volume.

Tape Mark

Scratch Tape

Indicates tape that is blank or that has not yet been
overwritten. Scratch tape can exist between the logical
end of volume and the EOT marker.

End of Tape
Marker (EOT)

Marks beginning of the end of the writeable area.

ZK-981-82

B.3.1

Beginning-of-Tape and End-of-Tape Markers
Every volume has beginning-of-tape (BOT) and end-of-tape (EOT) markers.
These markers are pieces of photoreflective tape that delimit the writable
area on a volume. ANSI standards require that a minimum of 14 feet to a
maximum of 18 feet of magnetic tape precede the BOT marker; a minimum of
25 feet to a maximum of 30 feet of magnetic tape, of which 10 feet must be
writable, must follow the EOT marker. The EOT marker indicates the start of
the end of the writable area of the tape, rather than the physical end of the
tape. Therefore, data and labels can be written after the EOT marker.

B-2

VMS ANSI-Labeled Magnetic Tape
B.3 Basic Components of the VMS ANSI-Labeled Format

B.3.2

Tape Marks
Tape marks separate the file labels from the file sections, separate one file
from another, and denote the logical end-of-volume. On the basis of the
number and relative placement of tape marks written on a volume, the VMS
system determines whether a tape mark delimits a label, a file, or a volume.
Tape marks are written both singly and in pairs. Single tape marks separate
either a file section from the header and trailer labels or one file from another.
When written after a set of header labels, a single tape mark signals the
beginning of a file section. When written before a set of trailer labels, a single
tape mark indicates the end of a file section. When written after a trailer label
set, a single tape mark separates one file from another.
Double tape marks indicate that either an empty file section exists or the
logical end-of-volume has been reached. The VMS system creates an empty
file when a volume is initialized.

8.3.3

Labels
Labels identify, describe, and control access to volumes and their files. The
VMS ANSI-labeled format supports volume, header, and trailer labels. The
volume labels are the first labels written on a volume. They identify the
volume and the volume owner and specify access protection. Header and
trailer labels are sets of labels that identify, describe, and delimit files. Header
labels precede files; trailer labels follow files.
Table B-1 lists the labels supported by the VMS operating system. All other
ANSI labels are ignored by VMS on input.
Although each type of label uses a different format to organize its contents,
all labels conforming to Version 3 of the ANSI standard must consist of ASCII
a" characters. Some labels contain reserved fields designed for future system
use or future ANSI standardization. Reserved fields also must consist of
ASCII a" characters; however, VMS ignores these characters on input.
11

8.4

Volume and File Configurations
VMS ANSI-labeled volumes support four file/volume configurations:
•

Single-file/single-volume

•

Single-file/multivolume

•

Multifile/single-volume

•

Multifile/multivolume.

All these configurations conform to the following guidelines:
•

The file sequence number field allows as many as 9999 file sections for
one file. In effect, the file length is unlimited.

•

Only one file section of a given file is written on a volume.

B-3

VMS ANSl-Labe1ed Magnetic Tape
8.4 Volume and File Configurations

•

When multiple sections exist for one file, each file section is written
to a separate volume in the volume set. The file section numbers of
each section are written consecutively in ascending order (section n+l is
written immediately following section n); file sections of other files are
not interspersed.

Each of the file/volume configurations is illustrated in the subsections that
follow.
Table B-1
Symbol

B.4.1

Labels and Components Supported by VMS

Meaning

BOT

Beginning-of-tape marker

EOF1

First end-of-file label

EOF2

Second end-of-file label

EOF3

Third end-of-file label

EOF4

Fourth end-of-file label

EOT

End-of-tape marker label

EOV1

First end-of-volume label

EOV2

Second end-of-volume label

EOV3

Third end-of-volume label

EOV4

Fourth end-of-volume label

HDR1

First header label

HDR2

Second header label

HDR3

Third header label

HDR4

Fourth header label

VOL1

First volume label

VOL2

Second volume label

Tape mark

TMTM

Double tape mark indicates an empty file section or the logical end-ofvolume

Single-File/Single-Volume Configuration
A single-file/single-volume configuration consists of one file on one volume.
The components of the ANSI-labeled format for this configuration are
illustrated in Figure B-2.

B-4

VMS ANSI-Labeled Magnetic Tape
8.4 Volume and File Configurations

Figure B-2

• • •

Single-File/Single-Volume Configuration

BOT

VOL 1

HDR1

HDR2

HDR3

First File

EOF1

EOF2

EOF3

TM TM

Scratch
Tape

•••
ZK-346-81

B.4.2

Single-File/Multivolume Configuration
A single-file/multivolume configuration consists of one file that spans two or
more volumes in a volume set. Figure B-3 illustrates the components of the
ANSI-labeled format for this configuration.

B.4.3

Multifile/Single-Volume Configuration
A multifile/single-volume configuration consists of two or more files on
a single-volume. It is the most common file and volume configuration.
Figure B-4 illustrates the components of the ANSI-labeled format for this
configuration.

B-5

VMS ANSI-Labeled Magnetic Tape
8.4 Volume and File Configurations

Figure B-3

•••

Single-File/Multivolume Configuration

BOT

VOL 1

HDR1

HDR2

HDR3

First Section of First File

EOV2

EOV3

TM TM

• • •

HDR2

HDR3

EOT

• • •

Continuation Volume

• • •

BOT

VOL 1

HDR1

Second Section of File

JMEOF1

EOF2

EOF3

TM TM

• • •

*When the driver encounters an EOT marker during a write operation, the MTAACP writes
the appropriate trailer labels and performs a volume switch, if necessary.

ZK-347-81

B-6

VMS ANSI-Labeled Magnetic Tape
B.4 Volume and File Configurations

Figure B-4

Multifile/Single-Volume Configuration

• • •

BOT

VOL 1

HDR1

TM EOF1

EOF2

EOF3

HDR2

HDR1

HDR3

HDR2

HDR3

Second File

EOF2

EOF3

TM TM

Scratch
Tape

EOT

Scratch
Tape
ZK-345-81

B.4.4

Multifile/Multivolume Configuration
A multifile/multivolume configuration consists of two or more files that span
two or more volumes in the same volume set. Figure B-5 illustrates the
components of the ANSI-labeled format for this configuration.

B-7

VMS ANSI-Labeled Magnetic Tape
B.4 Volume and File Configurations

Figure 8-5

Multifile/Multivolume Configuration

First Volume

• • •

BOT

VOL 1

HDR1

HDR2

HDR3

First File

EOF3

TM • • •

HDR1

HDR2

First Section of Nth File

EOT TM

EOV1

EOV2

EOV3

TM TM

• • •

HDR1

HDR2

HDR3

Continuation Volume

• • •

BOT

VOL 1

Second Section of Nth File

EOF3

TM. • • •

HDR1

HDR2

First Section of (N+ 1)th File

EOT TM

EOV1

EOV2

EOV3

TM TM

*When the driver encounters an EOT marker during a write operation, the MT AACP writes
the appropriate trailer labels and performs a volume switch, if necessary.
ZK-348-81

8.5

Volume Labels
The sections that follow describe the first volume (VOLl) and second volume
(VOL2) labels.

8-8

VMS ANSI-Labeled Magnetic Tape
B.5 Volume Labels

8.5.1

VOL 1 Label
The SO-character volume label (VOLl) is the first label written on a VMS
ANSI-labeled volume. It defines the label type, name, and owner of the
volume. Although there are many fields in a VOLl label, this section
describes only those fields that you can access or that can inhibit access
to a volume and its files on VMS.

B.5.1.1

Volume Identifier Field
The volume identifier field is a 6-character field that contains the name of the
volume. You specify the volume identifier in the command string when you
initialize or mount a volume (see Chapter 3). The volume identifier consists
of six ASCII a" characters. Lowercase characters are not in the a" set, but if
you specify them, VMS will change them to uppercase. If you specify fewer
than six characters, VMS pads the field by right-justifying the field with the
ASCII space character.
/1

8.5.2

B.5.1.2

Accessibility Field
The accessibility field is a one-character field that allows an installation to
control access to a volume. See Section 2.1.3 for a description of accessibility
support.

B.5.1.3

Implementation Identifier Field
The implementation identifier field contains the identifier of the
implementation that creates the magnetic tape. This field controls how
certain implementation-specific fields and volume labels are interpreted. The
magnetic tape file system's implementation identifier is DECFILEll A.

B.5.1.4

Owner Identifier Field
The owner identifier field is available to the user. This field does not affect
the checking of a user's access to a volume, except as noted in Chapter 3.

VOL2 Label
In addition to the first volume (VOLl) label described above, VMS also
provides a second volume (VOL2) label, the volume-owner field.
The volume-owner field contains the VMS protection information that has
been written on the magnetic tape. A second volume label is written only
if a VMS protection scheme had been specified on either the MOUNT or
INITIALIZE command.
The volume-owner field also contains a value that incorporates the user
identification code (UIC) with the VMS protection code specified for a volume.
By default, VMS does not write a UIC to this field, thus allowing all users
READ and WRITE access. Note, however, that EXECUTE and DELETE access
are not applicable to magnetic tape volumes. Also note that, regardless of the
protection code that you specify, both system users and the volume owner
always have READ and WRITE access to a volume. The contents of the
volume-owner field depends on the VMS protection code that you specify.

B-9

VMS ANSI-Labeled Magnetic Tape
B.6 Header Labels

8.6

Header Labels
The VMS operating system supports four file-header labels: HDRl, HDR2,
HDR3, and HDR4. The HDR3 and HDR4 labels are optional. The following
sections describe and illustrate each file-header label.

8.6.1

HDR1 Label
Every file on a volume has a HDRl label, which identifies and describes the
file by supplying the VMS MTAACP with the following information:

B.6.1.1

•

File identifier

•

File-set identifier

•

File section number

•

File sequence number

•

Generation and generation version numbers

•

File creation and expiration dates

•

Accessibility code

•

Implementation identifier

File Identifier Field
The file identifier field contains the first 17 characters of the file name you
specify. The remainder of the file name is written into the HDR4 label,
provided that this label is allowed. If no HDR4 label is supported, a file name
longer than 17 characters will be truncated. You may use either an ANSI file
name or a VMS file specification of the following format:
filename. type ;version

VMS file specifications are a subset of ANSI file names. However, ANSI file
names are valid only for magnetic tape volumes; VMS file specifications are
valid for disk and tape volumes. Both types of file specifiers are compatible
with compatibility mode.
A VMS file specification consists of a file name, a file type, and an optional
version number. Valid file names contain a maximum of 39 characters. Valid
file types consist of a period followed by a maximum of 39 characters. The
semicolon separates the version number from the file type.
Except for wildcard characters, only the characters A through Z, 0 through
9, and the special characters ampersand ( & ), hyphen ( - ), underscore (-)
and dollar sign ( $ ) are valid for VMS file names and types. The period and
semicolon are the only other valid special characters, and they are always
separators.
ANSI file names do not have a file type field. An ANSI file name consists of
a 17-character name string, a period, a semicolon, and an optional version
number. You can specify a name string consisting of a maximum of 17 ASCII
"a" characters, but you must enclose the string in quotation marks (as in, for
example, "file name"). When you specify fewer than 17 characters, the string
is padded on the right with spaces to the 17-character maximum size. If you
specify a file name that has trailing spaces, VMS truncates them when the

B-10

VMS ANSI-Labeled Magnetic Tape
8.6 Header Labels

file name is returned. In addition, the space-padded field prevents you from
specifying a unique file name that consists of spaces.
Although you can specify longer file names (up to 79 characters), only the
first 17 characters of the file name will be used in interchange.
The quotation mark character requires special treatment because it is both
the file name delimiter and a valid ASCII "a" character that can itself be
embedded in the name string. You must specify two quotation marks
for each one that you want the VMS system to interpret. The additional
quotation mark informs VMS that one of the quotation marks is part of the
name string, rather than a delimiter.
Embedded spaces also are valid characters, but embedded tabs are not.
Lowercase characters are not in the ASCII "a" character set, but if you specify
them, VMS converts them to uppercase characters.
If you do not specify a file type or version number on input, VMS will supply
a period (the default file type) and a semicolon (the default version number).
However, the period and semicolon will not be written to this field on the
tape.

Although the VMS operating system considers version numbers for ANSI
and VMS file names to be part of the file name specification, the version
number of a file is not written to the file identifier field but is mapped to
the generation number and generation version-number fields as described in
Section B.6.1.4.
Examples below display ANSI file names. The input is the format that you
specify. The output shown displays the VMS format returned to your process
and the format written to the label. The number sign ( #) in the examples
indicates a space character. In the last example, a VMS file name is enclosed
in quotation marks, like an ANSI file name, on input. However, the VMS
operating system returns the file name to the process as a VMS file name,
rather than an ANSI file name. Therefore, when you enclose a valid VMS file
name in quotation marks on input, VMS parses the file name as a VMS file
name.
Input
"AB2&D""FgHI*k4""#-M";2
"##########"

"""""""""""""""""""""""""""·
"DWDEVOP.DAT"
"VMS_LONG_FILENAME.LONG_FILETYPE"
Output to User Process
"AB2&D""FGHI*K4""#-M";2

"" .
""""""""""""""""""""""""""""

DWDEVOP.DAT;
VMS_LONG_FILENAME.LONG_FILETYPE
Output to HDR1 Label
AB2&D"FGHI*K4"#-M

B-11

VMS ANSI-Labeled Magnetic Tape
8.6 Header Labels

#################
"""""""""""""####
DWDEVOP.DAT######
VMS_LONG_FILENAME

B.6.1.2

File-Set Identifier Field
The 6-character file-set identifier field denotes all files that belong to the
same volume set. The file-set identifier for any file within a given volume set
should always be the same as the file-set identifier of the first file on the first
volume that you mount. For VMS, the file-set identifier is the same as the
volume identifier of the first volume that you mount.

B.6.1.3

File Section Number and File Sequence Number Fields
The file section number is a 4-character field that specifies the number of the
file section.

The file sequence number is a 4-character field that specifies the number of
the file in a file set.

B.6.1.4

Generation Number and Generation Version-Number Fields
The generation number (a decimal number from 0001 to 9999) and generation
version-number (a 2-digit decimal number) fields store the file version number
specified on input and written by the system on output. The VMS operating
system does not increment the version number of a file, even when the
version of the specified file already exists on the volume. Therefore, if the file
that you specify has the same file name and version number as an existing
file, you will have at least two files with the same version number on the
same volume set.

On input, VMS computes the version number by using this calculation:
version number =
[(generation number - 1) * 100]

+ generation version-number + 1

Version numbers larger than 32,767 are divided by 32,768; the integer
remainder becomes the version number.
On output, the generation number is derived from the version number with
this calculation:
generation number = [(version number - 1)/100]

If there is a remainder after the version number is divided by 100, the
remainder becomes the generation version number. It is not added to 1 to
form the generation number.

B.6.1.5

B-12

Creation Date and Expiration Date Fields
The creation date field contains the date the file is created. The expiration
date field contains the date the file expires. The system interprets the
expiration date of the first file on a volume as the date that both the file
and the volume expire. The creation and expiration dates are stored in the
Julian format. This 6-character format (#YYDDD) consists of a space ( # ), the
year, and the day. Only dates are relevant for these fields; time is always
returned as 00:00:00:00.

VMS ANSI-Labeled Magnetic Tape
8.6 Header Labels

By default, the current date is written to both the creation and expiration
date fields when you create a file. Because the expiration date is the same
as the creation date, the file expires on creation and you can overwrite it
immediately. If the expiration date is a date that is later than the creation
date and if the files you want to overwrite have not expired, you must specify
the /OVERRIDE=EXPIRATION qualifier with the INITIALIZE or MOUNT
command.
To write dates other than the VMS defaults in the date fields in this label,
specify the creation date field (CDT) and the expiration date field (EDT) of the
RMS date and time extended attribute block (XABDAT).
When you do not specify a creation date, VMS RMS defaults the current date
to the creation date field. To specify a zero creation date, you must specify
a year before 1900. If you specify a binary zero in the date field, the system
will write the current date to the field.
For details on the XABDAT, see the VMS Record Management Services Manual.

B.6.2

B.6.1.6

Accessibility Field
The contents of this field are described in Section B.5.1.2.

B.6.1.7

Implementation Identifier Field
The implementation identifier field specifies, using ASCII "a" characters, an
identification of the implementation that recorded the Volume Header Label
Set.

HDR2 Label
The HDR2 label describes the record format, maximum record size, and
maximum block size of a file.

B.6.2.1

Record Format Field
The record format field specifies the type of record format the file contains.
The VMS operating system supports two record formats: fixed length (F) and
variable length (D). When files contain record formats that the system does
not support, it cannot interpret the formats and classifies them as undefined.

Fixed-length records are all the same length. No indication of the record
length is required within the records because either the HDR2 label defines
the record length or you specify the record length with the /RECORDSIZE
qualifier. A fixed-length record can be a complete block, or several records
can be grouped together in a block.
Fixed-length blocked records are padded to a multiple of 4 records. Variablelength records are padded to the block size. If a block is not filled, it will be
padded with circumflex characters (A). The standard does not allow records
containing only circumflexes; the system will interpret this as padding, not
data.
Figure B-6 shows a block of fixed-length records. Each record has a fixed
length of 50 bytes. All six records are contained in a 300-byte block. The
records are blocked-that is, grouped together as one entity-to increase
processing efficiency; when records are blocked, you can access many of them
with one I/O request. The block size should be a multiple of the record size.

B-13

VMS ANSI-Labeled Magnetic Tape
8.6 Header Labels

Figure 8-6

REC
50 Bytes

Blocked Fixed-Length Records

REC
50 Bytes

BLOCK
300 Bytes

ZK-353-81

The size of a variable-length record is indicated by a record control word
(RCW). The RCW consists of four bytes at the beginning of each record. A
variable-length record can be a complete block, or several records can be
grouped together in a block.
Two variable-length records are shown in Figure B-7. The first consists of
54 bytes, including the RCW. The second consists of 112 bytes, including the
RCW. The records are contained in a 166-byte block.
Do not use system-dependent record formats on volumes used for information
interchange. VMS system-dependent formats are stream and variable with
fixed-length control (VFC).
Figure 8-7

Variable-Length Records

Record Size = 54 Bytes

RCW
54

DATA
50 Bytes

Record Size = 112 Bytes

DATA

RCW
112

108 Bytes

Pad
Characters
14 Bytes

BLOCK
180 Bytes

ZK-354-81

8.6.2.2

Block Length Field

The block length field denotes the maximum size of the blocks. According to
the ANSI standard, valid block sizes range from 18 to 2048 bytes. However,
the VMS operating system allows you to specify a smaller or larger block size
by using the /BLOCKSIZE qualifier with the MOUNT command. To specify
the block size using VMS RMS, see the BLS field in the file access block (FAB)
in the VMS Record Management Services Manual. When you specify a block
size outside the ANSI standard range, the volume may not be processed
correctly by other systems that support the ANSI standards.

8-14

VMS ANSI-Labeled Magnetic Tape
B.6 Header Labels

B.6.2.3

Record Length Field
The record length field denotes either the size of fixed-length records or the
maximum size of variable-length records in a file. Valid VMS record sizes
vary, depending on the record format. The range for fixed-length records is
1 to 65,534 bytes; the range for variable-length records is 4 to 9,999 bytes,
including the 4-byte RCW. Therefore, the maximum length of the data area of
a variable-length record is 9,995 bytes. To comply with ANSI standards, the
record size should not be larger than the maximum block size of 2,048 bytes,
even though VMS allows larger record sizes (when the block size is larger).

For volumes containing files that do not have HDR2 labels, you must specify
MOUNT /RECORDSIZE=n at mount time. The variable n denotes the record
length in bytes. Files without HDR2 labels were created by a system that
supports only level 1 or 2 of the ANSI standard for magnetic tape labels and
file structure. Records should be fixed length because this is the only record
format that either level supports. If you do not specify a record size, each
block will be considered a single record.

B.6.2.4

Implementation-Dependent Field
The implementation-dependent field contains two 1-character subfields that
describe how the VMS operating system interprets record format and form
control.

The first subfield, character position 16, denotes whether the RMS attributes
are in this label or the HDR3 label. If character position 16 contains a space,
the RMS attributes are in the HDR3 label; if it contains any character other
than a space, character position 16 is the first byte of the RMS attributes in
the HDR2 label. The attributes appear in character positions 16 through 36
and 38 through 50.
For volumes created by any VMS version up to and including Version 2.0,
the system-dependent fields of the HDR2 label contain the RMS file attributes
in binary format. For volumes created on VMS versions later than Version
2.0 (Version 2.1 to the present), the magnetic tape file system stores the RMS
attributes.
The second subfield, the form control field at character position 37, specifies
the form control that defines the carriage control applied to records within
a file. Possible values supported for VMS magnetic tape volumes are listed
below.

B.6.2.5

First byte of record contains FORTRAN control characters.

The record contains all form control information.

space

Line-feed/carriage-return combination is to be inserted between records
when the records are written to a carriage-control device, such as a line
printer or terminal. If form control is not specified when a file is created,
this is the default.

Buffer-Offset Length Field
For implementations that support buffer offsets, the buffer-offset length
field indicates the length of information that prefixes each data block. The
magnetic tape file system supports the input of buffer offset, which means
that the buffer-offset length obtained from the HDR2 label (when reading the
file) is used to determine the actual start of the data block. The magnetic tape
file system does not support the writing of a buffer offset.

Note that, if you open a file for append or update access and the buffer-offset
length is nonzero, the open operation will not succeed.

B-15

VMS ANSI-Labeled Magnetic Tape
B.6 Header Labels

B.6.3

HDR3 Label
The HDR3 label describes the RMS file attributes. For RMS operations, data
in the HDR3 label supersedes data in the HDR2 label.
Although the HDR3 label usually exists for every file on a VMS ANSI-labeled
volume, there are two situations when this label will not be written. The
first is when an empty dummy file is created during volume initialization; no
HDR3 label is written because the empty file does not require RMS attributes.
The second is when you specify MOUNT /NOHDR3 at mount time. You
should use the /NOHDR3 qualifier when you create files on volumes that
will be interchanged to systems that do not process HDR3 labels correctly.
The RMS attributes describe the record format of a file. These attributes are
converted from 32 bytes of binary values to 64 bytes of ASCII representations
of their hexadecimal equivalents for storage in the HDR3 label.

B.6.4

HDR4 Label
The HDR4 label contains the remainder of a VMS file name that would not
fit in the HDRl file identifier field.

B. 7

Trailer Labels
The VMS operating system supports two sets of trailer labels: end-of-file
(EOF) and end-of-volume (EOV). A trailer label is written for each header
label.
EOF and EOV labels are identical to their file header label counterparts except
that:
•

The label identifier field (characters 1-3) contains EOF or EOV.

•

The block count field (characters 55-60) in the EOFl and EOVl labels
contains the number of data blocks in the file section.

The particular label that VMS writes depends on whether a file extends
beyond a volume. If a file terminates within the limits of a volume, EOF
labels are written to delimit the file (see Figure B-2). If a file extends across
volume boundaries before terminating, EOV labels are written, indicating that
the file continues on another volume (see Figure B-3).

B-16

Index
Allocation (cont'd.)

A
Access
append operation• 4-19
CONTROL• 2-9, 2-11, 2-12
DELETE•2-9, 2-11, 2-12
EXECUTE• 2-9, 2-11
file attributes• 4-18
READ• 2-9, 2-11
to file• B-13
magnetic tape• 4-16
to volume
magnetic tape• 4-16
types of• 2-2, 4-20
update operation• 4-19
WRITE• 2-9, 2-11
Access category
summary of• 2-1
Access Control Entry
See ACE
Access control list
See ACL
Accessibility field•2-12, B-9, B-13
Access type
CONTROL•2-2
DELETE•2-2
EXECUTE•2-2
READ•2-2
WRITE•2-2
ACE (access control entry)• 2-8, 2-9, 2-12
ACL (access control list)
default protection• 2-8
defining with DCL • 2-3
description of• 2-3
SHOW ACL command• 2-13
ACL-based protection• 2-3
See ACL
ALLOCATE command• 3-20
See also Allocation
/GENERIC qualifier• 3-2
magnetic tape• 4-1 5, 5-2
Allocation
of disk drive• 3-1
generic• 3-2, 3-3
of disk volume• 4-8, 4-9

of magnetic tape drive• 3-1
of magnetic tape volume• 4-1 5
ANSI data• B-1
ANSI file name• 4-18, B-10
ANSI-labeled magnetic tape
mounting• 3-12
ANSI-labeled volume• B-1, B-3
accessibility protection• 2-4
copying files from • 5-3
format• B-1
ANSI standard • B-1
structure of magnetic tape• 1-6
Append access• 4-19
ASCII "a" character set• 5-3, B-1, B-3
percent sign• 4-18
Asterisk (*)
wildcard character• 4-1 7

B
BACKUP .SYS• A-3
Backup log file• A-3
Backup operation• 1-8
BADBLK.SYS • A-2
Bad block file• A-2
BADLOG.SYS • A-3
Batch job
accessing devices• 3-21
Beginning-of-tape marker
See BOT marker
Binary data• B-1
Bit map
index file• A-2
storage• A-2
BITMAP .SYS• A-2
Blocked record • B-13
Block length field• B-14
Bootstrap block• 1-5, A-1
BOT (beginning-of-tape) marker• B-2
Buffer-offset length field• B-1 5

lndex-1

Index

c
Close operation • 4-19, 4-20
Command procedure• 1-8
accessing foreign volumes• 4-20
login•2-8
magnetic tape restriction • 4-1
setting up disk volume• 3-21
setting up magnetic tape volume• 3-22
setting up volume• 3-20
using to copy files• 5-12
CONTIN.SYS • A-3
Continuation file• A-3
Continuation volume
mounting• 3-1 7
CONTROL access• 2-3
See Access
Convert Utility (CONVERT)
using to transfer information• 5-8
COPY command • 4-1 , 5-1
ANSI-labeled volumes
copying from • 5-3
disk files• 5-2
/LOG qualifier• 5-7
magnetic tape• 4-15
copying files from • 5-3
copying to• 5-2
non-file-structured volumes• 5-6
Core image file• A-3
CORIMG.SYS • A-3
Corruption of data • 3-19
CREA TE command
magnetic tape• 4-19
CREA TE/DIRECTORY command• 2-12 4-15
Creation date field • B-1 2
'
zero creation date• B-13

D
DCL commands
restrictions on• 4-1
DEALLOCATE command • 3-20
magnetic tape• 4-16
Default protection • 2-8
DELETE access
See Access
explicity assigning• 2-12

lndex-2

Device
accessing in batch job• 3-21
magnetic tape
retrieving information • 4-6
protection• 2-13
Directory
creating• 4-15
protection• 2-12
DIRECTORY command•2-13, 4-2, 4-18
/FULL qualifier• 4-18
magnetic tape• 4-4, 5-2
Disk
accessing
examples of• 4-13
allocating to process• 3-1
allocation of space on• 1-4, 4-8, 4-9
basic concepts• 1-2
block
cluster• 1-2
description of• 1-2
copying files• 5-2
deallocating drives• 3-20
default format• 5-2
file
copying• 5-1
See also COPY command
copying to magnetic tape• 4-15
file characteristics
modifying• 4-10
mounting• 3-8
See also MOUNT command
protection• 2-6
structure
Files-11•1-5
volume protection
See Protection
access types• 2-5
volume set
See Volume set
Disk quota• 4-8
Disk structure
Files-11 • A-1
DISMOUNT command• 3-18, 3-20
/FOREIGN qualifier• 3-19
magnetic tape • 4-16
/NOUN LOAD qualifier• 3-18
/UNIT qualifier• 3-18
Dismounting
foreign volumes• 3-19
volumes• 3-18

Index

DOS-11
volume•5-3, 5-10
Double tape mark• B-3

E
End-of-tape marker
See EOT marker
EOF (end-of-file) label• B-3, B-16
EQT (end-of-tape) marker• 8-2
EOV (end-of-volume) label• B-3, B-16
Exchange Utility (EXCHANGE)• 5-1, 5-10
DCL level • 5-11
DIRECTORY command• 5-11
exiting from • 5-11
invoking• 5-11
MOUNT command • 5-11
EXECUTE access
See Access
Expiration date field• 4-16, B-12
Extent• 1-2

F
File
copying from magnetic tape• 5-3
copying to magnetic tape• 4-15
creating • 1-6
identifier field• B-10
index file• 1-6
nonstandard format• 4-2, 4-13
privileges• 2-8
reserved files
list of• A-1
volume configurations• B-3, 8-4, B-5, 8-7
File access
See Access
on disk
examples of• 4-13
on magnetic tape volumes
examples of• 4-13
File access block (FAB) • B-14
File header• 1-5
description of• 1-6
Files-11 structure• A-2
File header label
See Header label

File name
ANSl•4-18
VMS•4-18
File protection• 2-8
See also Protection
Files-11 disk
Exchange Utility (EXCHANGE)• 5-3, 5-10
structure• 1-2, A-1
Level 1•5-2
Level 2•5-2
reserved files• A-1
structure levels compared• A-3
File section number field• 8-12
File sequence number field • B-12
File-set identifier field• B-12
File specification• B-10
ANSl•4-18
File type field• B-10
Fixed-length record • B-13
Foreign volumes
mounting • 3-8
See also MOUNT command• 3-8
Format
ANSI-labeled volume• 8-1

G
Generation version number• 8-12

H
Header label • B-3
HDR1 label•2-4, B-10
accessibility field• B-13
creation date field • B-1 2
expiration date field• B-12
file identifier field • B-10
file section number field• B-12
file sequence number field• 8-12
file-set identifier field • B-12
generation number field• 8-12
generation version-number field• B-12
HDR2 label • B-10, B-13
block length field • 8-14
buffer-offset length field • B-1 5
record format field• 8-13
record length field • B-15

lndex-3

Index

Header label
HDR2 label (cont'd.)

Label (cont'd.)

system-dependent field • 8-15
HDR3 label• 8-10, 8-16
RMS attributes field • 8-16
HDR4 label•8-10, 8-16
information on• 1-7
on magnetic tape• 4-1 7
Home block• 1-5, A-1

HDR3•8-16
HDR4•8-16
header• 8-9
ISO• 8-1
trailer• 1-7, 8-16
VOL 1 •8-8
Logical name table• 3-7
Login command procedure• 2-8

Identifier field
file • 4-1 7, 8-10
file-set• 8-12
implementation• 8-9
owner•3-13, 8-9
volume•3-13, 3-17, 8-9
Index file• 1-6, 3-9
bit map•A-2
description of• 1-5
INDEXF.SYS • A-1
INITIALIZE command• 3-3
See also Volume
continuation volumes• 3-1 7
Files-11 On-Disk Structure• 3-4
magnetic tape• 5-2
protection codes• 4-11
using to set protection• 2-6
Initializing
disk volume• 3-4
magnetic tage volume• 3-5
magnetic tape volume• 4-7
volume•3-3
Installation routine• 2-4
Interchange environment
protection• 2-7
ISO standard• 8-1
structure of magnetic tape• 1-6

Magnetic tape
accessing
examples of• 4-13
allocation of• 3-1, 4-15
ANSI-labeled
mounting• 3-1 2
basic concepts of• 1-6
block• 1-7
copying files from• 5-3
deallocating drives• 3-20
density• 1-7
DOS-11•5-3, 5-10
file• 1-7
reading • 4-18
file protection

L
Label
ANSI• 8-1, 8-3
EOF (end-of-file)• 8-16
EOV (end-of-volume)• 8-16
HDR1 •8-10
HDR2•8-13

lndex-4

See Protection
initializing• 3-5
installation routine• 2-4
interrecord gap (IRG) • 1-7
label format• 3-12
modifying device characteristics• 4-10
mounting • 3-11
See also MOUNT command• 3-11
reading from• 4-19
record blocking• 1-7
record format • 5-3
retrieving device information• 4-6
specifying block size• 3-12
specifying record size• 3-15
9-track drive• 8-1
volume•5-2
See Volume
volume protection
See Protection
volume set
See Volume set
writing files to• 4-1 5, 4-19

Index

Magnetic tape ancillary control process
See MTAACP
MAIL
protection• 2-13
Master file directory
See MFD
Media
See Disk
See Magnetic tape
MFD (master file directory)• A-2
MOUNT command• 2-6, 3-6, 3-20
/ASSIST qualifier• 3-7
/A UT OMA TIC qualifier• 3-18
/BIND qualifier• 3-9
/BLOCKSIZE qualifier• 3-12, 5-8, B-14
/CACHE=T APE_DAT A qualifier• 3-14
/FOREIGN qualifier• 3-13, 4-13, 5-6
/GROUP qualifier• 3-7
/HDR3 qualifier• 3-1 5
/INITIALIZE qualifier• 3-18
magnetic tape• 5-2
/NOLA BEL qualifier• 5-8
/OVERRIDE qualifier• 3-13, 4-16
/OWNER_UIC qualifier• 3-14
protection codes • 4-11
/PROTECTION qualifier• 3-14
qualifiers• 3-12
/RECORDSIZE qualifier• 3-15, 5-8, B-15
specifying logical names• 3-6
specifying record size• 3-15
specifying UIC • 3-14
/SYSTEM qualifier• 3-7
Mount request• 3-7
MT AACP process• B-1
Multifile/multivolume configuration• B-7
Multifile/single-volume configuration• B-5
Multivolume file• 1-7

0
OPCOM message
continuation volume request • 5-4
Operator Communication Facility
See OPCOM
Ownership
display• 2-13

p
Pending bad block log file• A-3
Percent sign (%)
wildcard character• 4-17
Private volume
See Volume
Privileges
BYPASS•2-3
GRPPRV•2-1
SYSNAM•2-6
SYSPRV•2-1, 2-6, 3-9
VOLPRO (volume protection override)• 2-3,
3-4,3-8
Protection
access category
summary of• 2-1
ACL-based • 2-3
categories of• 2-1
changing• 2-6
default• 2-8
changing• 2-10
device• 2-13
directory• 2-12
disk volume• 2-6
display• 2-13
file•2-1, 2-8
default• 2-10
directory• 2-8, 2-11
disk• 2-8, 2-9
magnetic tape• 2-3, 2-8, 2-12
for interchange environments• 2-7
mail file• 2-13
mask•2-6
nonfile device• 2-14
UIC-based • 2-1
volume•2-1
ANSI-labeled• 2-4
disk•2-5
magnetic tape• 2-5, 2-6
Protection code
changing• 2-10
for magnetic tapes • 3-14
for volumes • 3-14
specifying• 2-9

lndex-5

Index

SET PROTECTION command (cont'd.)

Q
Queue 1/0 services
$QIO call • B-1

R
RCW (record control word)• B-14
READ access
See Access
Read operation• 4-14
continuation volumes• 5-5
disk •4-14
magnetic tape• 4-16, 4-19
ANSI-labeled• 4-1 7
Record
number of bytes in• 3-15
Record control word
See RCW
Record format
fixed-length • B-1 3
variable-length• B-13
Record format field • B-13
Record length field • B-1 5
Record Management Services (RMS)
See VMS RMS
Reinitalizing
volumes• 3-19
REPLY command
/BLANK_TAPE qualifier• 5-5
/INITIALIZE_TAPE qualifier• 5-5
/TO qualifier• 5-4, 5-5
RMS (Record Management Services)
See VMS RMS
Root volume• 3-8
RT-11
volume • 3-12
block-addressable • 5-3, 5-10

s
SET ACL command• 4-9
SET DIRECTORY command• 4-9
SET FILE command• 4-9, 4-10
SET MAGT APE command• 4-9, 4-10
SET PROTECTION command• 4-9, 4-11

lndex-6

/DEFAULT qualifier• 2-10
SET VOLUME command• 4-9
SHOW ACL command•2-13, 4-2
SHOW command• 4-1
SHOW DEVICES command• 2-13, 3-16, 4-2,
4-4
SHOW MAGT APE command• 4-2, 4-6
SHOW PROCESS command• 2-13
SHOW PROTECTION command•2-13, 4-2, 4-7,
4-8
SHOW QUOTA command•4-2, 4-8
Single-file/multivolume configuration• 8-5
Single-file/single-volume configuration• 8-4
Storage bit map file• A-2
Stream record type• B-14
SUBMIT command• 4-1
System-dependent field• 8-15
System privilege• 2-1

T
Tape
See Magnetic tape
Tape mark• 8-3
Tape marker
BOT•B-3
EOT•8-3
Terminal
protection• 2-14
Trailer label• 1-7, 8-3, 8-16
TYPE command
foreign volumes • 5-10
magnetic tape• 4-18

u
UIC
default protection• 2-8
format• 2-1
specification • 3-14
UIC-based protection• 2-1, 2-12
default• 2-8
to bypass• 2-3
Update access • 4-19
User category
types of access• 2-2

Index

User identification code
See UIC

v
Variable-length record• B-14
Version number• 4-17, B-11
VFC (variable with fixed-length control) record
format • B-14
VMS Record Management Services
See VMS RMS
VMS RMS (Record Management Services) • B-1 ,
B-13,B-14
attributes• B-15, B-16
VOL 1 label• 2-4
See Volume label
VOL label
See Volume label
VOLSET .SYS• A-3
Volume
ANSI-labeled magnetic tape• B-3
copying files from• 5-3
mounting• 3-12
continuation• 3-17
file configurations• B-3, B-4, B-5, B-7
foreign• 3-8
header labels• 3-15
initializing• 3-3, 3-4, 3-5
label•B-3
label format• 3-12
magnetic tape• 5-2
ANSI-labeled• 5-3
copying files from• 5-3
deallocating • 4-16
dismounting• 4-16
initializing• 4-15
mounting• 3-11
record format• 5-3
writing files to• 4-15
modifying characteristics of disk• 4-13
mounting• 3-6, 3-8
See also MOUNT command
mounting with EXCHANGE• 5-11
mounting without HDR2 labels • B-1 5
operator assistance • 3-7
owner field • B-9
private• 3-1
Volume identifier field• 3-17, B-9

Volume label
EOF (end-of-file) label• B-3
EOV (end-of-volume) label• B-3
VOL 1 label• B-8
accessibility field • B-9
volume identifier field• B-9
VOL label• B-3
Volume protection
See Protection
Volume RT-11 •3-12
Volume set
adding to• 3-11
adding volumes• 3-11
creating • 3-9, 3-10
creation of• 3-10
defining• 3-10
disk•3-9
add volume • 3-11
mounting • 3-8
initializing• 3-9
list file• A-3
loosely coupled• A-3
magnetic tape
automatic volume switching • 3-17
continuation volumes• 3-17
creating • 3-16
mounting • 3-15
maximum number in set• 3-11
mounting• 3-6, 3-8
See also MOUNT command
naming• 3-9, 3-10
processing continuation volumes• 3-15
Volume sets
privileges• 3-9

w
Wildcard character
used in directory specifications• 4-4
used with file • 4-17
used with magnetic tape • 4-1 7
WRITE access
See Access
Write-back caching• 3-14
Write operation• 4-14
continuation volumes• 5-5
disk •4-15
magnetic tape • 4-1 5, 4-16, 4-19
ANSI-labeled• 4-1 7

lndex-7

Index

x
XA8DA T (extended attribute) block• 8-13
CDT (creation date) field• 8-13
EDT (expiration date) field• 8-13

z
Zero creation date• 8-13

lndex-8

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