Look in the manuals about "collocation". It is turned on at the
storagepool level.

        Look also in the archives as there are a lot of threads about
pros and cons about using it.

Ben


-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Alexander Lazarevich
Sent: Wednesday, May 19, 2004 11:01 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Data organization on tape storage pool?


Hi TSMers,

TSM 5.1.6.5 on windows 2K server. Library is overland storage neo 4100
with 60 LTO-2 tapes, and 2 X LTO-2 HP drives. Setup the system last
July, works just fine. But I'm a little curious how data is organized on
tape volumes. I don't have a problem with anything, but I'm very curious
what the logic is to how the server decides what data is put on what
volume.

For example, I noticed that data from a single client is on several
different tapes. And as data is put on the tape storage pool, the server
finds the tape which has a volume status of 'filling', and there is only
one such tape, so it dumps data on there regardless of what client that
data belongs to. Also, space reclamations can further jumble up the data
on tapes, so that a client may have data on several different tapes.

My questions is this: is there any way to control the organization of
the data on the tape storage pool. For example, could I force all data
from a single client to be put on a single tape, and if it needed
another tape for data, it would grab a scratch tape only, and avoid
putting data on a tape that has other client data on it. In addition to
that, the server would probably be forced to have x many tapes with a
volume status of 'filling', one for each client that backs up, right?
Space reclamations could work fine, it just deletes the old data, then
moves any data from a tape belonging to that client back onto another
tape belonging to that client.

I suppose in this scenario, there might be a lot of waisted tape space,
because many clients have more data than the 200GB LTO-2 can store, so
each client might have one tape which is only using, in theory, 1% of
capacity.

Anyone have any comments? Should I just leave it alone? Did tivoli study
and come up with the best way to organize the data? Or is this something
that people mess around with to get better performance?

Thanks in advance,

Alex
---                                                               ---
   Alex Lazarevich | Systems Administrator | Imaging Technology Group
    Beckman Institute | University of Illinois | www.itg.uiuc.edu
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