Re: Space reclamation of offsite copy pool takes forever

2002-11-11 22:39:12
Subject: Re: Space reclamation of offsite copy pool takes forever
From: "Seay, Paul" <seay_pd AT NAPTHEON DOT COM>
Date: Mon, 11 Nov 2002 22:38:25 -0500
This is why I do not use the reclaimation process.  I have written a process
that does MOVE DATA vvvvvv reconstruct=yes commands for the volumes that
have less than a reclamation number.  I set the reclamation in the storage
pool to 100 so they will not reclaim.

Then I can run as many simultaneously as my drives can handle, usually 5 to
6.  Yes, from the same storage pool.

We actually do this because we use closed box and the tapes may return
before they are empty, so 14 days before there return I move the data to new
volumes going offsite.  I also have a second threshold.  If the tape has
been offsite more than say 14 days and is less than say 10% utilized I
reclaim them as well.

There are many beauties to this process and only a couple negatives.  You
get your tapes refreshed at the offsite no matter what.  You can use closed
box.  Keeps the tapes full at whatever level you want.  Allows you to have a
built in scratch pool for disaster recovery.  Keeps collocated volumes down
to a minimum (fewer mounts).  On the negative side, it requires tape drives.
The process is home grown using TSM selects and AIX KSH scripts.

We use separate pools for database and exchange backups or similar type
data.  Those backups do not have to be recycled before return because there
are always full copies of these offsite.

Maybe ITSM development will take a look at doing something like this in the
future.  This is the case for smaller storage pools and more of them.

Paul D. Seay, Jr.
Technical Specialist
Naptheon Inc.

-----Original Message-----
From: Brazner, Bob [mailto:Bob.Brazner AT JCI DOT COM]
Sent: Monday, November 11, 2002 6:44 PM
Subject: Space reclamation of offsite copy pool takes forever

Reclamation of our offsite copy pool is taking forever.  Right now, we have
200+ volumes in that pool.  Normally, threshold is set at 60% and I get
maybe 8 or 9 volumes returned after processing for 7 hours (on beefy AIX,
with TSM at 5.1.5).  Lately I've tried setting the threshold at 99, then 98,
then 97, etc., but I don't see much improvement in overall freeing up of
tapes.  It appears that most of the time is taken up with mounting input
volumes.  Even though we have a 3494, I'd say 80% of the time is spent
waiting for tape mounts.  Is there any way to get space reclamation to free
up offsite tapes faster?  Note, for my onsite tape pool, I do not see this
problem (e.g., I can easily free up 30 tapes in 5 hours or less).

Bob Brazner
Johnson Controls, Inc.
(414) 524-2570