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AN-014

November 2000

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Document:	Accessing SCSI & IDE disk drives with CHARON-VAX
Order Number:	AN-014
Revision:	0
Pages:	2
Original Filename:	AN-014.pdf

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CHARON-VAX application note
AN-014 Accessing SCSI & IDE disk drives with CHARON-VAX
Author:

Software Resources International

Date: 29-Nov-2000

CHARON-VAX can directly access a SCSI or IDE disk attached to a CHARON-VAX host system and
use it just like a physical disk on a MicroVAX. It is even possible boot a VAX operating system from
this attached SCSI or IDE disk. As an example, this note documents the procedure for attaching a
SCSI or IDE disk to CHARON-VAX. To understand the throughput, we have indicated the disk I/O
performance we measured with a Digital RZ-25E SCSI disk attached to CHARON-VAX running under
Windows 2000.

Step 1: Connecting a SCSI or IDE disk to a CHARON-VAX host
Physically connect the required disk to the host system. In case of an IDE disk connect the drive to the
IDE main board connectors, use a SCSI controller card or embedded SCSI controller in case of a
SCSI disk. The procedure for detecting and configuring physical SCSI or IDE disks depends on the
operating system used:
Windows NT/2000.
Ensure that the attached disk is not allocated to Windows. Run the utility “Disk Administrator”
(Windows NT) or “Disk Manager” (Windows 2000) to make sure that the disks dedicated to CHARONVAX are not allocated by the Windows operating system.
OpenVMS
Any disks visible under the host system can be used by CHARON-VAX. Note that the disks should be
dismounted or mounted as foreign under the host’s OpenVMS before using of them under CHARONVAX.
Linux
Under Linux just note the names of the connected disks to be used when configuring CHARON-VAX.

Step 2: Configuring CHARON-VAX
Use the process described in the CHARON-VAX Users Guide to identify and configure your SCSI or
IDE disks. See the section on mapping physical host system disks in the chapter on Emulation of
Components. This allows you to associate the SCSI or IDE disks to CHARON-VAX, for example:
Windows 2000 or Windows NT:
SET DUA file[2]=”\\.\PhysicalDrive1”
OpenVMS:
SET DUA file[2]=”DKA100:”
Linux:
SET DUA file[2]=”/dev/hda”

Test Environment & Test Procedure Description
For the performance measurement the following configuration was used:
Component
Base system

Disks
Ethernet
Operating System

Description
Intel P2 system 500Mhz, 2CPU’s
64Mb RAM
S3 video board
SCSI adapter NCR
FDD 3.5”
IBM 9 GB IDE ATA (Disk0),
Digital RZ-25E SCSI (Disk1)
4 port card using Digital 143 chipset
Windows 2000 Professional

Purpose/ Comment

Disk Caching is enabled

©2000 Software Resources International. This document is provided for information only and is not a legally binding offer.
Software Resources International reserves the right to change the product specifications without prior notice or retire the
product. The CHARON name and its logo are a registered trademark of Software Resources International. For further
information: www.charon-vax.com, Email: vaxinfo@vaxemulator.com

CHARON-VAX application note AN-014
Four groups of tests were performed:
1. Copying one big file and then a large group of small files from one folder to another on the same
attached disk (Disk1):
a. On a physical disk mapped as a disk device under CHARON-VAX
b. On a disk image placed on the disk, used in the test a.
2. Copying one big file and then a large group of small files between:
a. A physical disk mapped as a disk device under CHARON-VAX (Disk1) and disk image
placed on the main disk (Disk0) of the host system
b. Two disk images, one of them was placed on the main disk of the host system (Disk0),
and the other on the physical disk, used in the test a (Disk1).

Observed disk performance
File Transfer on the same disk:
1a. Disk1, used as a physical drive:
Test Description
Copying one large file
Copying a large group of files

Copied Blocks
111573
108798

Time, sec
127
300

Speed, Kb/sec
439.26
181.33

1b. Using a CHARON-VAX disk Image placed on the attached Disk1:
Test Description
Copying one large file
Copying a large group of files

Copied Blocks
111573
108799

Time, sec
182
257

Speed, Kb/sec
306.52
211.7

Copied Blocks
111573
111573
108799

Time, sec
50
40
189

Speed, Kb/sec
1115.73
1394.66
287.82

108799

130

418.46

File Transfer between disks:
2a. Disk1, used as a physical drive:
Test Description
Copying one large file (Disk0->Disk1)
Copying one large file (Disk1->Disk0)
Copying a large group of files (Disk0>Disk1)
Copying a large group of files (Disk1>Disk0)

2b. Using a CHARON-VAX disk image placed on the attached Disk1:
Test Description
Copying one large file (Disk0->Disk1)
Copying one large file (Disk1->Disk0)
Copying a large group of files (Disk0>Disk1)
Copying a large group of files (Disk1>Disk0)

Copied Blocks
111573
111573
108799

Time, sec
93
60
147

Speed, Kb/sec
599.85
929.80
370.06

108824

120

453.43

Conclusions for this particular configuration:
1.

Copying between disks or disk images located on different drives is faster than using a single
drive. This is probably due to the use of a dual CPU system.

Copying large files gives a higher throughput than copying groups of small files.

There is no clear speed advantage between using a full disk or a disk image, transfer speed highly
depends on file size. In terms of ease of use, a disk image file can be more easily handled by the
host operating system (e.g. backup).

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