Under the covers the VTS is, guess what, ADSM/TSM.

Now, that said, each logical volume is 800MB.  The append operation that TSM
would be doing to each tape could be nasty.  What has to happen is the
logical 800MB volume has to be recalled appended to, and rewritten to a new
tape.  So, I would expect a lot of reclamation going on in the VTS as a
result because every time a backup was run it would have to rebuild the
append.

I might be totally wrong about this, but thinking how a computer works and
the VTS, I have to believe it would be nasty.

Now, there is a possibility.  Set your TSM reclamation to 100% for that
pool.  Mark every volume in the pool read only each day or after every
backup cycle.  A script would easily do this.  This would cause every
collocation to go to a new volume each backup cycle.  That would eliminate
the VTS reclamation, but may make things ugly.  So, I would tradeoff and set
the reclamation to a number say, 90 or 95%.  Or only mark a volume read only
when it gets more than x percent full.  It is all about tradeoffs.

One day collocation groups will come.  Just a matter of time.

Paul D. Seay, Jr.
Technical Specialist
Naptheon Inc.
757-688-8180


-----Original Message-----
From: Bill Boyer [mailto:bill.boyer AT VERIZON DOT NET]
Sent: Friday, October 04, 2002 9:58 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Anyone using VTS for storage pool volumes?


We have a client that wants to move their small occupancy nodes to their VTS
and turn on collocation. Is there anyone using a VTS for TSM storage pool
volumes? I would like to hear about your experiences. I'm just not
comfortable with how appending data to an existing VTS volume works. Seems
like you would be doing a lot of reclamation within the VTS.

TIA,
Bill Boyer
DSS, Inc.