ADSM-L

Reclamation

2000-07-14 13:30:45
Subject: Reclamation
From: Gerald Wichmann <gwichmann AT SANSIA DOT COM>
Date: Fri, 14 Jul 2000 10:30:45 -0700
We have a magstar that just recently received an upgrade by adding a 2nd
tape drive to it.. previously when doing reclamation we have our reclamation
pool configured as 8GB of sequential file space on one of the internal
drives. This worked great but there was a little thrashing going on during
reclamation.. the reclamation process would start and copy data from tape to
the pool. The pool would fill up fairly quickly and kick off migration back
to tape.. with only 1 tape drive, the reclamation process would halt until
migration finished.. and well it would alternate like that until reclamation
was complete.

Now that theres a 2nd tape drive, we have a problem..

Reclamation starts and uses one of the drives. The pool fills up and starts
a migration process which mounts a scratch tape in the 2nd drive.
Reclamation fails because it fills up the reclamation pool and then
basically keeps cycling until the migration pool frees up enough space to
allow the reclamation process to continue. So in a sense theres still
thrashing going on but with lots of failure messages in the activity log
saying the reclamation pool is full.

Now that there?s two tape drives it seems logical to stop using the disks as
a reclamation pool and just have reclamation go tape to tape. The disks were
purchases specifically for reclamation but I suppose we could find other
uses for them. My question is mostly just to pick everyone?s mind about this
configuration and what would be the best given this situation.

Gerald Wichmann
RS Engineer
Sansia System Solutions
408-844-8893 work
408-844-9801 fax
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