Hello all,

I think I should share my experience and ask for experience and opinions.
The environment (we are installing for a customer):
IBM 3583 with 3 drives + SAN Data Gateway Module connected to IBM 2109
(i.e. Brocade) switch
TSM server v4.2.1.15 (or may become 4.2.2) on Windows 2000 (its a small
shop)
3x MgSysSAN on AIX 4.3.3 (rest is LAN)

According to Tivoli flash 2 we could have problems only if there are at
least two Windows-based TSM servers or Storage Agents. And we have only
one - ought to be no problem.
One of the drives will be used from IBM iSeries server so the library was
"zoned" through SDG module to allow TSM & SAN access only to drives 2&3
from one FC port. Drive 1 was left to iSeries through other FC port of SDG
module. Library sharing with iSeries is not a threat.
Here comes the problem. After reconfiguration of SDG Windows box lost the
first drive (the iSeries one) and drive 2 (former \\.\TAPE02) became
\\.\TAPE01. Drive 3 (former \\.\TAPE03) became \\.\TAPE02. All this was
due to Windoze "wizdom" and happened on the TSM server. Drives were empty
at this moment so server ended up with library not working (all later
mount attempts failed due to element mismatch and drives went offline).

Now the question I am asking myself and hoping for your help.
Mount retension of drives is not zero. If drive transition happens during
write operation on drive 2 and drive 3 holding a tape because of mount
retension the next block written will go to \\.\TAPE02 but this might be
drive 3. Tivoli's temporary resolution for flash 2 is by using SCSI
Reserve command.
1. Will the drive 3 be RESERVED when is idle with cartridge loaded or not?

2. Which piece of software will issue Reserve and Release SCSI commands -
TSM or Ultrium driver?
3. Wouldn't Windows plug-n-pray reset SCSI bus thus unlocking device?
I already scheduled some additional test to perform myself at customer's
SAN TSM zone. For most of you this might be very deep technically but I am
afraid of potential data corruption/loss this might lead to. Any opinions
would be highly appreciated.

Zlatko Krastev
IT Consultant