ADSM-L

[ADSM-L] Possible performance issue with TSM 7.1.0.x / DB2 10.5.x in large dedup environment

2014-08-19 06:29:39
Subject: [ADSM-L] Possible performance issue with TSM 7.1.0.x / DB2 10.5.x in large dedup environment
From: Bent Christensen <BVC AT COWI DOT DK>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 19 Aug 2014 12:27:39 +0200
Hi all,

Just wanted to direct your attention to this blog entry by Josh-Daniel Davis if 
you are using TSM 7.1 in a large dedupped environment: 
http://omnitech.net/reference/2014/08/04/db2-10-5-0-1-negative-colcard

We had a backup system in flames and 2 severity 1 PMRs open for more than 6 
weeks with TSM L2 support and DEV being pretty clueless, and yesterday the 
problem was solved (fingers crossed) by changing the COLCARD value from a 
negative to a positive value as described in the above blog.

We experienced this problem as db2syscs.exe constantly utilizing 80-85 % CPU on 
a 32-core server, growing queue of dereferenced chunks, fragments in FILE 
devclass pool volumes not being removed which renders those volumes unusable 
and expiration, reclamation and client backups failing or running very slow.

There are no fixes (yet) and TSM support recommends regularly monitoring of the 
db2 tables for negative COLCARD values.

Apparently a DB2 APAR IT03792 exists but it is pretty new and has not been 
published to external IBM websites yet. A TSM APAR is on its way.

 - Bent 


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