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Document:	VAX/VMS Bad Block Locator Utility Reference Manual
Order Number:	AA-Z435A-TE
Revision:	000
Pages:	28
Original Filename:	aa-z435a-te.pdf

OCR Text

VAX/VMS
Bad Block
Locator Utility
Reference Manual
Order No. AA-Z435A-TE

software
lilgliftlall]

VAX/VMS
Bad Block Locator Utility
Reference Manual
Order Number: AA-Z435A-TE

September 1984
This document describes the Bad Block Locator Utility for use on VAX
processors.

Revision/Update Information:

This is a new manual.

Software Version:

VAX/VMS Version 4.0

digital equipment corporation

maynard, massachusetts

September 1984

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.

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

DIBOL

UNIBUS

DEC/CMS
DEC/MMS

EduSystem
IAS

VAX
VAXcluster

DECsystem—-10
DECSYSTEM-20

PDP
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DECUS

RSTS

DECnet

DECwriter

MASSBUS

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VMS

Emu
ZK-2305

This document was prepared using an in-house documentation production system.

All

page composition and make-up was performed by TgX, the typesetting system developed

by Donald E. Knuth at Stanford University. TgX is a registered trademark of the American
Mathematical Society.

BAD Contents
PREFACE

NEW AND CHANGED FEATURES

A4
vii

FORMAT

BAD-1

DESCRIPTION

BAD-2

LOCATING BAD BLOCKS

BAD-2

RECORDING BAD BLOCKS

BAD-2

Location of the Detected Bad Block File

BAD-2

2.2

Format of the Detected Bad Block File

BAD-3

RUNNING BAD ON DEVICES CONVERTED TO

NON-LAST-TRACK FORMAT

BAD-3

RUNNING BAD INTERACTIVELY FROM YOUR
TERMINAL

BAD-4

RUNNING BAD FROM COMMAND PROCEDURES

BAD-4

ERROR MESSAGES

BAD-5

COMMAND QUALIFIERS

BAD-6

/BAD_BLOCKS

BAD-7

/EXERCISE

BAD-9

/LOG

BAD-10

/OUTPUT

BAD-11

/RETRY

BAD-12

/SHOW

BAD-13

BAD Contents

INDEX

TABLES
BAD-1

Block-Addressable Devices

BAD-5

Preface

Intended Audience
This manual is intended for VAX/VMS system managers, operators, and
system programmers.

Structure of This Document
This document is composed of three major sections.

The Format Section is an overview of BAD and is intended as a quick

reference guide. The format summary contains the DCL command that
invokes BAD, listing all qualifiers and keywords. The usage summary

describes how to invoke and exit from BAD, how to direct output, and
any restrictions you should be aware of.
The Description Section explains how to use BAD.

The Qualifier Section describes each DCL command qualifier. Qualifiers
appear in alphabetical order.

Associated Documents
For additional information on the topics covered in this document, refer to
the VAX/VMS DCL Dictionary and the Guide to VAX/VMS System Management
and Daily Operations.

Conventions Used in This Document
Convention

Meaning

[rem)

A symbol with a one- to three-character

abbreviation indicates that you press a key
on the terminal, for example,

[RET] .

The phrase CTRL/x indicates that you must press
the key labeled CTRL while you simultaneously
press another key, for example, CTRL/C,
CTRL/Y, CTRL/O.

$ SHOW TIME

05-JUN-1985 11:56:22

Command examples show all output lines or
prompting characters that the system prints

or displays in black letters. All user-entered
commands are shown in red letters.

Preface

Convention

$ TYPE MYFILE.DAT

Vertical series of periods, or ellipsis, mean either
that not all the data that the system would
display in response to the particular command is
shown or that not all the data a user would enter
is shown.

file-spec,...

Horizontal ellipsis indicates that additional
parameters, values, or information can be
entered.

[logical-name]

Square brackets indicate that the enclosed item
is optional. (Square 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 (”). The term apostrophe

(') is used to refer to a single quotation mark.

New and Changed Features
The Bad Block Locator Utility no longer has an interactive interface. BAD
functions are performed using the DCL command ANALYZE/MEDIA, along
with the qualifiers documented here.

vii

BAD

BAD
The Bad Block Locator Utility (BAD) analyzes block-addressable
devices and records the locations of blocks that cannot reliably
store data. Table BAD—1 at the end of the description section
describes the devices that BAD can analyze.

FORMAT

ANALYZE/MEDIA device
Command Qualifiers

/BAD_BLOCKS]=flist)]

Defaults

None.

/[NOJEXERCISE[~(keyword],...]J)] /NOEXERCISE
7INOJLOG

/NOLOG

/[NOJRETRY
/SHOW/=(keywordy,...])]

/NORETRY
None.

/OUTPUT|<file-spec]

None.

Command Parameter
device

Specifies the device containing the volume that BAD will analyze. The device
name has the form
ddeu:

usage summary

or logical-name

Invoking

To invoke BAD, at the DCL command prompt enter the command ANALYZE
/MEDIA along with any parameters or qualifiers.
Exiting

Once invoked, BAD will run until completion. When BAD terminates, control
is returned to the DCL command level.
Directing Output

You can write the contents of the Detected Bad Block File (DBBF) to an

output file by specifying the /OUTPUT qualifier. See the description of the
/OUTPUT qualifier in the qualifier section.
Privileges/Restrictions

To ensure that the device is not accessed by any other programs, you must

allocate the device with the DCL command ALLOCATE. See the VAX/VMS
DCL Dictionary for more information on the ALLOCATE command.
After you have allocated the device, you must give the DCL command
MOUNT with the /FOREIGN qualifier. When the device is mounted foreign,

the operating system does not recognize it as a Files-11 volume, and BAD
can execute.

BAD-1

BAD
Description

DESCRIPTION

BAD locates bad blocks on a volume by testing whether the same data that is
written onto blocks can be read back. When it finds a bad block, BAD writes
the address of that block onto the Software Detected Bad Block File (SDBBF).
When you run BAD to test a device (using the /EXERCISE qualifier), keep in
mind that:

The device cannot be accessed by other programs,

The device cannot be mounted as a Files~11 volume,

The device is always purged by BAD’s testing procedure; any information
stored on the disk is destroyed.

Caution: There is no way to test the volume for bad blocks without destroying
its contents. However, you can update the DBBF without erasing the
volume’s contents by using the BAD qualifiers /NOEXERCISE and
/BAD_BLOCKS.
After BAD locates and records the bad blocks, you issue the DCL command

INITIALIZE to change the volume from unstructured format to Files-11
format and to allocate the faulty blocks to a special file on the volume called
[000000]BADBLK.SYS. In this way, users are protected from accessing them
for their files. For more information on Files-11 format and the INITIALIZE
command, see the VAX/VMS DCL Dictionary.

Locating Bad Blocks
To test the blocks on a volume, BAD

Writes a test pattern to each block on the disk

Reads the contents of the block into a buffer

Compares the data read back with the data written

If the data does not compare exactly, a block cannot reliably store data.

Recording Bad Blocks
When BAD locates a bad block, it records the address of the block.

Consecutive bad blocks are recorded as single entries for non-last-track
devices. After it finishes testing the disk, BAD writes the addresses of the bad
blocks into an area called the Detected Bad Block File (DBBF).

Location of the Detected Bad Block File
The location of the DBBF depends on whether the volume is a last-track
device, that is, one that contains more than 4096 blocks (512 bytes per block).
Last-track devices store bad block data on the last track of the disk.
The first half of the track is reserved for the Manufacturer’s Detected Bad
Block File (MDBBF). The MDBBF stores the bad blocks discovered by the
manufacturer when the device was originally formatted.
The second half of the track is reserved for the Software Detected Bad Block
File (SDBBF).

BAD-2

BAD
Description

Non-last-track devices are devices that contain 4096 blocks (512 bytes per
block) or less. These devices do not set aside the last track of the disk to store
bad block information. Instead, BAD creates the DBBF on the last good block
of the disk. There must be at least one reliable block in the last 256 blocks of

the volume for BAD to generate the DBBF.

2.2

Format of the Detected Bad Block File
If the volume is a last-track device, each DBBF entry contains the cylinder,

track, and sector address of the faulty block.
On volumes that are not last track, DBBF entries contain the number of bad
blocks minus 1, and the logical block number (LBN) of the faulty block or
sequence of faulty blocks. A single entry can address one bad block or several
contiguous bad blocks.
The DBBF can contain a maximum of 126 entries. For both last-track and
non-last-track devices, BAD terminates with an error message when the
maximum number of entries is exceeded. However, the contents of the

SDBBF on the medium remains intact.

Running BAD on Devices Converted to Non-Last-Track Format
If you have run the compatibility mode BAD using the /OVR (override)
qualifier on a device designated as last-track, the medium on the device has
been converted to non-last-track format. When you run the native mode BAD
on such a device, BAD treats it as a last-track device and will therefore fail
to find the Manufacturer’s Detected Bad Sector File (MDBSF). Depending on
which qualifiers you specify with the ANALYZE/MEDIA command, you can
expect the following results when running BAD on a converted device:
*

If you do not attempt to modify the medium on the device (if you specify
/NOEXERCISE /OUTPUT, for example), BAD will, upon failing to locate
the MDBSF, attempt to find the Software Detected Bad Sector File (SDBSF)
and will produce an output listing using the non-last-track format.

If you attempt to modify the medium preserving the SDBSF (if you specify
/EXERCISE=KEEP or /NOEXERCISE /BAD_BLOCKS, for example), BAD
will terminate with the following fatal diagnostic message:

% BAD-F-MDBSFRFAIL, Failed to read the manufacturer's detected bad sector file on DEVICENAME

Note that all attempts to preserve the SDBSF when modifying the medium on

a converted device will fail. However, if you do not attempt to preserve the
SDBSF (by specifying /EXERCISE=KEEP, for example), BAD will recreate the
MDBSF and SDBSF and will continue testing. For example, you could use the
following command to run BAD on the converted device DB1:
$ ANALYZE/MEDIA/OUTPUT=DB1TEST.ANL DB1

ANALYZE/MEDIA
DB1:

16-APR-1984 08:16:63.97

PAGE 1

(DBA1:), SERIAL NUMBER: O

SOFTWARE DETECTED BAD BLOCKS

LOGICAL BLOCK NUMBER

88308

COUNT

DEVICE DBA1:CONTAINS A TOTAL OF 340670 BLOCKS;

1 DEFECTIVE BLOCK DETECTED

ANALYZE/MEDIA/EXERCISE/OUTPUT=DB1TEST.
ANL DB1:

BAD-3

BAD
Description

Running BAD Interactively from Your Terminal
When you run BAD interactively from your terminal, use a sequence of
commands similar to the following:
$ ALLOCATE DBA2:
DBA2:

ALLOCATED

$ MOUNT/FOREIGN DBA2:

YMOUNT-1-MOUNTED

mounted on DBA2:

$ ANALYZE/MEDIA/EXERCISE DBA2:
$ INITIALIZE DBA2

The ALLOCATE command requests the allocation of a specific disk drive,

DBA2:. The response from the ALLOCATE command indicates that the

device was successfully allocated. The MOUNT/FOREIGN command
mounts the disk volume as a foreign disk. The MOUNT command response

indicates that DBA2: was successfully mounted. The ANALYZE/MEDIA
command invokes BAD. Specifying DBA2: and the /EXERCISE qualifier
causes BAD to analyze each block on this disk volume and to record the
bad blocks. The INITIALIZE command reformats the volume as a Files-11
volume and allocates the bad blocks to a special file on the volume called

[000000]BADBLK.SYS. Once allocated, they cannot be used by other files.

Running BAD from Command Procedures
You can invoke BAD from a VAX/VMS command procedure. Following is a
typical command procedure, named NEWDISK.COM, that invokes BAD and
gives other DCL commands.

$! THIS COMMAND PROCEDURE EXERCISES AND INITIALIZES THE
$! SPECIFIED DISK.

$!
$! P1 IS THE DEVICE
$! P2 IS THE VOLUME LABEL

$!
$!

$ IF P1 .EQS.
" THEN § INQUIRE P1 "DEVICE TO BE INITIALIZED"
$ IF P2 .EQS. "* THEN $ INQUIRE P2 "VOLUME LABEL"
$ ALLOCATE 'P1
$ MOUNT/FOREIGN 'P1

$ ANALYZE/MEDIA/EXERCISE 'P1
$ DISMOUNT/NOUNLOAD 'P1

$ INITIALIZE 'P1 'P2
$ EXIT

To run this command procedure, type the following command in response to
the DCL prompt:
@NEWDISK device volume-label

The operating system executes the commands in the order given within the
command procedure.

BAD—4

BAD
Description

Error Messages
The VAX/VMS Utilities Reference Volume lists the diagnostic messages
enerated by BAD, and provides explanations and suggested user actions
or these messages.

Table BAD-1

Block-Addressable Devices

Model

Code

Type

O rey

RBO2

Cart

2400

RLO2

Cart

2400

RMO3

Pack

RMOS

Pack

Cylinders

Bytes/Track

Bytes/Drive

512

10,240

10,485,760

512

10,240

10,485,760

3600

823

16,384

67,420,160

3600

823

16,384

256,196,608

3600

559

15,872

124,214,272

3600

569

15,872

124,214,272

Surfaces

RBSO

RMBO

RPOS

Pack

3600

a11

11,264

87,960,576

RPOS

Pack

3600

815

11,264

174,423,040

RPO7

Fix

3600

630

26,600

516,096,000

RKOS

Cart

2400

11,264

13,888,612

RKO7

Cart

2400

816

11,264

27,540,480

RXO1

Flop

360

3,328

266,266

RXO2

Flop

360

3,380

TUs8 @ DD

Cart.

Fix

6.656
@

256,256 ©

512,512 @
262,144

@ The RP07 has 16 surfaces but 32 tracks per cylinder.

BAD-5

BAD
Command Qualifiers

COMMAND

This section presents qualfiers for the ANALYZE/MEDIA command in

QUALIFIERS

alphabetical order. The qualifiers follow the standard rules of DCL grammar,

BAD-6

as specified in the VAX/VMS DCL Dictionary. Thus, you can abbreviate

any qualifier or keyword as long as the abbreviation is not ambiguous. The
asterisk and the percent sign can be used as wildcard characters unless
otherwise noted.

BAD
/BAD_BLOCKS

/BAD_BLOCKS
Adds the specified bad blocks to the DBBF. If the /BAD_BLOCKS

qualifier is specified along with the /EXERCISE qualifier, the medium
is tested once the bad blocks are added.

/BAD_BLOCKS/(=list)]

FORMAT

list

qualifier

keyword

Specifies codes for the the bad block locations to be added to the DBBF. If
you do not specify a value for the /BAD_BLOCKS qualifier, BAD prompts as
follows:
BAD_BLOCKS =

When it prompts, BAD reports any duplicate bad blocks. To terminate the
prompting session, type CTRL/Z.
Note: The term “block” denotes a standard unit of 512 bytes, whereas the

term “sector” denotes the physical size of the device sector, which is not
always the same for all devices. For example, an RL02 has a sector size of
256 bytes, while an RK07 has a standard sector size of 512 bytes.
Valid bad block location codes follow. You can specify them in any integer
combination or radix combination.

Code

Meaning

Ibn

Specifies the logical block number (LBN) of a single
bad block.

Ibn:count

Specifies a range of contiguous bad blocks starting
at the logical block number (LBN) and continuing
for “count” blocks.

sec.trk.cyl

Specifies the physical disk address (sector, track,

and cylinder) of a single bad sector. This code is
valid only for last track devices.

sec.trk.cyl:count

Specifies a range of bad sectors starting at the

specified physical disk address (sector, track, and
cylinder) and continuing for “count” sectors. This
code is valid only for last track devices.

EXAMPLES
@

§ ANALYZE/MEDIA/BAD_BLOCKS=(4.4.4:3) DB1:
The /BAD_BLOCKS qualifier in this example specifies a range of 3 bad
sectors beginning at the physical disk address sector 4, track 4, cylinder 4.
This range is added to the DBBF.

$ ANALYZE/MEDIA/EXERCISE/BAD_BLOCKS=(2) DB1

The command in this example adds the bad block specification to the DBBF

and then tests the medium. The bad block in this example is located at logical

block number (LBN) 2.

BAD-7

BAD
/BAD_BLOCKS

$ ANALYZE/MEDIA/EXERCISE/BAD_BLOCKS DB1
BAD_BLOCKS = 2 3
BAD_BLOCKS = 4

% BAD-I-DUPBLKNUM, duplicate block number 4, already exists in SDBBF
-BAD-I-SRCLIN, the source input entry was 4

BAD_BLOCKS =

BAD_BLOCKS=

BAD-8

In this example, BAD prompts for bad block specifications. Note that, in
prompt mode, BAD reports any duplicate bad blocks it detects.

BAD
/EXERCISE

/EXERCISE
Controls whether the medium should actually be tested. The default
is /NOEXERCISE.

FORMAT

JEXERCISE [~(keyword],...])]

qualifier
keywords

FULL
Causes BAD to test the medium using three test patterns (0’s, 1's, and “worst

/NOEXERCISE

case” ), instead of the default single “worst case” pattern. The FULL keyword

can be used only with /EXERCISE. Note that the “worst case” pattern always
remains on media tested with the /EXERCISE qualifier.

KEEP

Ensures the preservation of the current SDBBF. The KEEP keyword is the
default when /NOEXERCISE is specified.

NOKEEP

Causes BAD to create a new SDBBF. The NOKEEP keyword is the default
when /EXERCISE is specified. This keyword cannot be used with the
/NOEXERCISE qualifier.

PATTERN-(longword],...])

Allows users to specify the value of a test pattern to be used as “worst case.”

Up to an octaword of test pattern data may be specified in decimal (%D),
hexadecimal (%X), or octal (%O) radixes. The default radix is decimal.

The pattern is specified in longwords. If two or more longwords are specified,
they must be enclosed in parentheses and separated by commas.

—————————
S
[

EXAMPLES
0§ ANALYZE/MEDIA/EXERCISE=FULL DB1

The command in this example tests the medium using three test patterns. By
default, a new SDBBF is created.

$ ANALYZE/MEDIA/EXERCISE-KEEP DB1:

EE, DB1
XBADBADBA)
$ ANALYZE/MEDIA/EXERCISE=PATTERN=(YXFFEEFF

$ ANALYZE/MEDIA/NOEXERCISE/BAD_BLOCKS DB1

This command tests the medium while preserving the current SDBBF.

This command specifies a hexadecimal test pattern two longwords in length.
This command updates the DBBF without erasing the volume’s contents.

BAD-9

BAD
/LOG

/LOG
Specifies whether a message is sent to SYS$OUTPUT and to
SYS$ERROR indicating the total number of bad blocks detected
by BAD. The default is /NOLOG.

FORMAT

/[NOJLOG

EXAMPLE
$ ANALYZE/MEDIA /LOG DBB1:
Device DBB1:

contains a total of 340670 blocks;

11 defective blocks detected.

The command in this example requests BAD to report the total number of
bad blocks it detected on the device DBBI1:.

BAD-10

BAD
/OUTPUT

JOUTPUT
Specifies whether the contents of the DBBF are written to the

specified file. If you omit the /OUTPUT qualifier, no output is
generated.

When you specify /OUTPUT in conjunction with the /SHOW
qualifier, the default keyword for the /SHOW qualifier is AFTER.

FORMAT

JOUTPUT —[file-spec]

qualifier
keyword

file-spec
Identifies the output file for storing the results of the medium analysis. If you

specify a file type and omit the file name, the default file name ANALYZE is
used. The default file type is ANL. If you omit the file-spec, the results are
output to SYS$OUTPUT.

In place of the file-spec, you may specify an output device. In this case, BAD
writes the contents of the volume’s DBBF to a file called ANALYZE.ANL and
queues the file to the output device.
No wildcard characters are allowed in the file specification.

EXAMPLES
0

$ ANALYZE/MEDIA/OUTPUT=BADDBB.DAT DBA2:
The command in this example writes the contents of the DBBF from DBA2: to
the output file BADDBBF.DAT. Note that since /NOEXERCISE is the default,
the medium is not tested.

$ ANALYZE/MEDIA/OUTPUT=LPBO: DBA2:
The command in this example writes the contents of the DBBF from DBA2: to
the default file ANALYZE.ANL and queues the file to the print device LPB0:.

BAD-11

BAD
/RETRY

/RETRY
Enables the device driver to retry soft errors. The /RETRY qualifier

is used only in conjunction with the /EXERCISE qualifier. The default
is /NORETRY.

FORMAT

JEXERCISE /NORETRY
JEXERCISE /RETRY

EXAMPLE
$ ANALYZE/MEDIA /EXERCISE /RETRY DBAO:

The command in this example directs the device driver to retry soft errors.

BAD-12

BAD
/SHOW

/SHOW
Lists the contents of the DBBF before and/or after the medium is
exercised (tested).

FORMAT

/SHOW [=(keyword],...])]

qualifier
keywords

[NO]BEFORE,[NOJAFTER
Specifies whether the contents of the DBBF is listed before and/or after the
medium is exercised (tested). AFTER is the default.

EXAMPLES
£

$ ANALYZE/MEDIA/EXERCISE/OUTPUT/SHOW= (BEFORE,AFTER) DBA3:

The command in this example lists the contents of the DBBF both before
and after the disk DBA3: is exercised and directs the data to the currect

SYS$OUTPUT device.
B

$ ANALYZE/MEDIA/EXERCISE/OUTPUT/SHOW DBA3

The command in this example lists the contents of the DBBF only after the
disk DBA3: is exercised and directs the data to SYS$OUTPUT.

BAD-13

Index

Bad blocks

locating ® BAD-2

recording ® BAD-2
/BAD_BLOCKS qualifier*BAD-7

/RETRY qualifier * BAD-12
Running BAD

from command procedures ® BAD-4
in compatibility mode ®* BAD-3

in native mode ®BAD-3
interactively ® BAD-4

on coverted devices® BAD-3

Detected bad block file
format*BAD-3

location ® BAD-2
Directing output from BAD® BAD-1

/SHOW qualifier* BAD-13

/EXERCISE qualifier* BAD-9

Exiting from BAD ®BAD-1

Invoking BAD ® BAD-1

L
/LOG qualifier* BAD-10

o
/OUTPUT qualifierBAD-11

Index—1

VAX/VMS Bad
Block Locator Utility
Reference Manual

AA-Z435A-TE
_—

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