ADSM-L

Getting a Feel for Offsite Storage

2015-10-04 18:03:06
Subject: Getting a Feel for Offsite Storage
From: INTERNET.OWNERAD at SNADGATE
To: Jerry Lawson at ASUPO
Date: 11/26/97 5:45PM
Are you using DRM, or doing the management "manually"?

I can only speak for the manual process, as we have been doing it before DRM
became available.

I run the backup of the tape and DASD pools daily, to keep the process
shorter.  Do the DASD pools first - they run faster, since the number of tape
mounts are fewer (no input mounts).  Try to do them before a pool migrates -
as I understand it, once a tape is copied to tape by migrate, even if you
have caching turned on, the backup comes from tape.

Each day, I update the status on all FULL, Copypool tapes that are still
on-site and change them to offsite.  The messages that are generated from
this are trapped by a TMS routine that will tell the operator which tapes are
to go offsite.

Copypool tapes will be managed like any other tape pool - when the reclaim
threshold is reached, the tape will be reclaimed.  This process is different
for a copypool tape, though, in that the offsite tape can obviously not be
mounted for the reclaim.  Therefore, the data in the primary tape pool is
used as the source for creation of a new copypool tape.  When the process is
complete, the old copypool status changes to EMPTY, but it is not scratched,
since it is offsite.  Our practice here is to issue the Update Volume command
to change the status of all Empty, offsite tapes back to READWRITE.  This
then scratches the tapes.  We trap the messages through TMS, and inform the
tape management folks in the Data Center to have the tapes sent back from
offsite storage, and returned to the scratch pool.

The reclaim threshold is an interesting issue - as you probably know, it is
set at 60% (40% in use) for a normal tape pool.  I can't remember what the
default is for a copypool, but many will set it to 100%.  We did this for a
while, but wound up with a lot of tapes with one file on them.  We wanted to
set the pool at 10%, but had difficulty getting it there - it is currently
set at 4%.  Why did we have difficulty?  Once you have the copypool
established, and there are a fair number of tapes in it (for us,
approximately 3000), moving the reclaim threshold even 1% causes a lot of
tapes to be reclaimed.  and since the tapes are all offsite, (and our pools
are not collocated), there are sometimes 100 tape mounts required for a
reclaim.  It took us a week to go from 3 to 4 %.  (As I think of it, that was
when we ran expiration daily; we now run it weekly, so maybe the problem
won't be so severe.)

Hope this helps.

Jerry Lawson
jlawson AT thehartford DOT com


______________________________ Forward Header __________________________________
Subject: Getting a Feel for Off-site Storage
Author:  INTERNET.OWNERAD at SNADGATE
Date:    11/26/97 5:45 PM


I just created my first copy pool and ran a backup of my two primary tape
storage pools to the copy pool.  Once I "check out" the tapes in the copy
pool to send them off-site I still have a record of the tapes in the copy
 pool as available volumes but they are in an "offsite" state.  What's the
best way to manage the copy pool ?  Obviously I'll want to run at least a
weekly backup of my primary tape storage pool and I'll want to use new
tapes for the weekly backups.  How are other people managing copy pools and
what are some ways to set up a tape rotation for the copy pool.  I'm kind
of in that stage where I feel almost warm and fuzzy since I now have a
backup of my backup but now I am saying to myself "NOW WHAT"

Any suggestions or recommendations ?

Thanks
Scott Temonia
Network Engineer
Laitram Corporation
stemonia AT laitram DOT com
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