ADSM-L

Slow Reclamation from disk

2015-10-04 17:10:42
Subject: Slow Reclamation from disk
From: David Longo [mailto:David.Longo AT HEALTH-FIRST DOT ORG]
To: ADSM-L AT VM.MARIST DOT EDU
I have old TSM server 3.7.4.0 on AIX 4.3.3 with 3575-L32 library with
C-XL drives.  New server is TSM 4.2.1.9 on AIX 4.3.3 ML09 and
IBM 3584-L32 library with 8 FC-AL drives.

Having the 3584 running for about 6 weeks now, I see what some of
the talk about slownes in the last year actually is.  On BOTH TSM
systems there is slowness in offsite tape reclamation WHEN some
of the files being reclaimed are still on the Disk stgpool.

When tape reclamation starts, it figures out which tapes to reclaim and
where the data is - understand.  Then when it actually starts it
will copy files that are STILL in disk stgpool first before files that
are only on tape - makes sense.  Then move to files that are only on
tape.  However, when it is copying files from disk it is MUCH slower
than when copying from tape - I would say 10 times slower.

But when doing a MIGRATION disk to tape or BACKUP STGPOOL
fromdisk to tape on either system, it's like going from idle to 4th gear!
This slownes can happen on  thses system when there is NO OTHER
ACTIVITY but this single reclamation.

Having two different systems to compare at the same time seems
to indicate that this is NOT a disk problem or a tape problem (except
that the 3584 may not handle it quite as well).  Also our old system
tended to have disk pool emptier when reclaimation started and this
wasn't really noticed on that system until  I started paying close
attention.

I again point out that my 3584 really smokes when doing everything
else BUT reclamation from disk to tape.  So does the 3575 - relatively
speaking.

(My 3584 library is library F/W 2360 and drives are 18N2 as delivered,
I don't think this is problem but included for completeness).

It seems that this is some inherent Tivoli design flaw/feature in the
RECLAMATION process.  Anyone with detail  knowledge of
Reclamation can provide some insite?  Andy Raibeck?

Thanks,


David B. Longo
System Administrator
Health First, Inc.
3300 Fiske Blvd.
Rockledge, FL 32955-4305
PH      321.434.5536
Pager  321.634.8230
Fax:    321.434.5525
david.longo AT health-first DOT org



"MMS <health-first.org>" made the following
 annotations on 03/11/02 11:37:16
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