ADSM-L

Does Reclamation work for Tape Capacity?

2001-01-24 12:33:35
Subject: Does Reclamation work for Tape Capacity?
From: Scott Foley <sfoley AT NETDOCUMENTS DOT COM>
Date: Wed, 24 Jan 2001 10:19:59 -0700
I have a new setup of TSM and after a few months of random offsite storage I
am now sending copypool tapes offsite every day.  These tapes have a
capacity of 60 Gig, but currently the daily backup only needs 3 to 4 Gig on
them.  For the past week I have sent one database tape and one data tape
offsite each day.  Currently I have 10 data tapes offsite in the copypool,
but only 3 onsite in the tapepool.  In the next month I will send 30
additional tapes offsite that have 3-4 Gig on each for a total of 40 tapes
that hold less that 100 Gig (actual capacity = 2.4 T).  I want to combine
these 40 copypool tapes onto only 2 or 3 copypool tapes.

I had one person tell me that the reclamation process should do this for me.
I don't see this happening.  If I look at the copypool tape that was sent
offsite yesterday it lists a capacity of 2 Gig.  Utilization is 100% and
reclaim space is 0%.  This all sounds right, except that the capacity is
actually 60 Gig.  If the reclaim process is simply using the reclaim
percentage, and calculating that on the data, not the tape capacity,  then
it will be a long time until this tape is reclaimed.

So should the reclamation process work to combine tapes that are at .05%
capacity?  I don't see this happening.  I run "upd stg copypool reclaim=60"
and "upd stg copypool reclaim=100" two hours latter.  Nothing else is
happening on the system during this time.

If this won't work I am looking at using the "move data" command to move
data from an offsite copypool tape to a new onsite tape.  I then hope that a
subsequent move data from another offsite tape will move the data to the
same onsite tape.  Once this onsite tape is full (or within 5 days), I will
send it offsite and assume that the 7-8 offsite tapes that I used to make
the new one will eventually turn to a vault retrieve status.

If this is the way to go will I cause undue tape use If I do this
"reclamation" once a week?  I still want to send a new tape offsite each
day, that probably only has 3-4 Gig on it.  I can see myself combining seven
3 Gig tapes to one, then that 21 Gig tape and seven more 3 gig tapes to one,
then that 42 Gig tape and seven more 3 Gig tapes to one to get a full tape.
This process would take three weeks.  As our data grows, it will be less
common.

Any experience or advice would be appreciated.

Thank You
Scott Foley