DB2 LUW 9.5 performance issue

Michael Levine

DB2 LUW 9.5 performance issue
Hi List,



I have a difficult time following the digest version and I'm sorry if I
have not replied to all replies. Working with IBM we have identified
the cause (but not the fix) of the performance issue with 9.5. Using
DB2TOP we observed that with any type of non-matching index access (lots
of scanning) the asynchronous read I/O/second is three times faster on
64 bit UDB 8.2 and 9.1 than on 64 bit 9.5. During the queries we
observed A_SYNC I/O/second of 22,000 on 8.2 and 9.1 and only
7,000/second on 9.5. This was on identical hardware, identical queries
with the same bufferpool sizes, data and table structures. The UDB DB
cfg and instance parms were as close as possible - actually for the
testing we took the out of the box defaults. Prefetch options had
minimal affect and the bufferpools were purposely very small (5000 4k
pages).



Has anyone noticed similar behavior with 9.5 vs. 8.2 or 9.1 running in
64 bit (Red Hat) LINUX OS?



Regards,

Mike



Michael Levine
Senior Database Consultant
CGI-AMS
email: [login to unmask email]
Office: (850) 219-7719





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