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Document:	AN-021
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Original Filename:	AN-021.pdf

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CHARON-VAX application note
AN-021 Multi-volume VMS tape backup using MTD
Author:

Software Resources International

Date: 19 July 2001

The MTD utility is designed to generate CHARON-VAX tape image files from physical tapes and
vice-versa. The advantage of using tape image files is that emulated tape operations are not slowed
down because of physical tape movements. The ability of CHARON-VAX to dynamically change its
device mapping while it is running allows multi-volume operations with tape image files.
The following is an example of multi-volume backup of VAX/VMS running on CHARON-VAX for
Windows. The example is based on a configuration where the emulated tape drive MUA0 is used for a
backup operation in VAX/VMS:
1. In the configuration file is initially specified:
set MUA file[0]="image tape0.img" size[0]=409600

2. Boot VAX/VMS on CHARON-VAX, log in on the console terminal and start the backup:
VMS> backup/log/noassist/ignore=label dua0:[000000...]*.txt mua0:test.bck/rewind

3. When VMS prompts for a new tape in the console terminal, enter in the CHARON-VAX
command console the following commands:
set MUA file[0]="image tape1.img"
set MUA loaded[0]=yes

4. Enter "yes" to the backup prompt in the console terminal
5. Repeat 3 and 4 with a new tape image name until the backup is completed
6. Instruct VMS to dismount the emulated tape drive
7. You can now transfer the tape images (tape0.img … tapeN.img) off-line with MTD to an attached
physical SCSI tape drive at any convenient moment.
Backup restoration can be done in CHARON-VAX using the attached physical tape drive directly.
Assuming a running VMS system on CHARON-VAX:
1. Insert the first tape into the drive and enter in the CHARON-VAX command console the
following command (assuming the address of the SCSI drive is correct for this example):
set MUA file[0]="\\.\SCSI 2:0:3"

2. In the console terminal enter:
VMS> cre/dir dua0:[tst]
VMS> backup/restore/log/noassist/ignore=label mua0:test.bck/rewind dua0:[tst...]

3. VMS will process the first tape, eject it and ask for the second - load it and enter "yes", etc.
In the above example the physical tape drive is directly addressed via its SCSI port (no Windows
driver loaded). Direct SCSI addressing allows a faster transfer compared to the Win32 tape API. On
the other hand, the Win32 tape API can be used with non-SCSI tape drives.
[30-18-021]
©2001 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