ADSM-L

IBM 7331-205 to 305 conversion woes

1998-03-17 13:07:05
Subject: IBM 7331-205 to 305 conversion woes
From: Donald Coleman <coleman AT POST.QUEENSU DOT CA>
Date: Tue, 17 Mar 1998 10:07:05 -0800
We recently converted one of the IBM 7331 tape libraries on our ADSM system
from model 205 (7 GB 8mm Drives) to model 305 (20 GB AME (Mammoth) 8mm
drives. The existing tapes in the library were full and the expectation was
to copy the 7GB tapes over to the 20 GB tapes gradually.

While the new drives wre supposed to read 7GB tapes, a microcode error in
the drives meant that if you read a 7GB tape on a drive, in order to read or
write a 20GB tape on the same drive you had to:

    1. Clean the drive.
    2. Reset the memory in the drive (hold down the eject button for 10
seconds).
    3. Power the tape library off and on.

IBM is awaiting a fix from Exabyte (Tape Drive Manufactuer) for this problem.

This provided a major problem in trying to move the 7GB tapes off the
library. We also noticed that while the mammoth drives would read 7GB tapes
they would not do so reliably. MOVE DATA's would terminate with I/O errors.

To get around the problem,  we

   -  interchanged tapes and SCSI id's with a 7331-205 on the same SCSI
card. DRIVE3 became DRIVE1, etc.
   -  moved the 7 GB tapes to free slots in other tape libraries (MOVE DATA)

   - switched the tapes and addresses back to their original locations.

   - marked the 7GB tapes as "unavailable" so they wouldn't mount.

   - moved data from the other libraries to the new 20GB tapes to free up
space to repeat the process.

Since we were short on space on our remaining libraries, the above procedure
had to be repeated several several times in order  to move the 20 full 7GB
tapes off the library. The process took about a week.


 -----------------------------------------------------------
   Don Coleman,
   Queen's University Information Technology Services
   Kingston, Ont. Canada  K7L 3N6
   Tel: (613) 545-2034   Email: Don.Coleman AT QueensU DOT CA
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