[ADSM-L] Controling FILLING tapes at end of Migration

2012-03-12 19:38:23
Subject: [ADSM-L] Controling FILLING tapes at end of Migration
From: Roger Deschner <rogerd AT UIC DOT EDU>
Date: Mon, 12 Mar 2012 18:32:41 -0500
I'm having a problem with FILLING tapes multiplying out of control,
which have very little data on them.

It appears that this happens at the end of migration, when that one last
collocation group is being migrated, and all others have finished. TSM
sees empty tape drives, and less than the defined number of migration
processes running, and it decides it can use the drives, so it mounts
fresh scratch tapes to fill up all the drives. This only happens when
the remaining data to be migrated belongs to more than one node - but
that's still fairly often. The result is a large number of FILLING tapes
that contain almost no data. A rough formula for these almost-empty
wasted filling tapes is:

 (number of migration processes - 1) * number of collocation groups

Is there a way, short of combining collocation groups, to deal with this
problem? We've got a very full tape library, and I'm looking for any
obvious ways to get more data onto the same number of tapes. Ideally,
I'd like there to be only one FILLING tape per collocation group.

Roger Deschner      University of Illinois at Chicago     rogerd AT uic DOT edu
               Academic Computing & Communications Center ======I have
not lost my mind -- it is backed up on tape somewhere.=====

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