DB2 LUW 9.5 on 64bit Red Hat LINUX

Michael Levine

DB2 LUW 9.5 on 64bit Red Hat LINUX
Is anybody running DB2 LUW 9.5 (FP2a) on 64 bit Red Hat LINUX using 64GB
of memory on HP hardware? We are having performance problems that I
can't believe are actual bugs. First we cannot run with Instance memory
set to automatic (the server crashes). We have it capped at 32 GB to
prevent crashes. Now when we run a query with any WHERE predicate the
performance is terrible (when compared to the exact queries and data on
32 bit UDB 8.2). It runs fine when there is no where predicate! IBM
has been working with us on this and all of our database configuration
and instance level parms are OK. I was wondering how many sites are
running OK with this configuration?



Thanks,

Mike





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




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Philip Gunning

Re: DB2 LUW 9.5 on 64bit Red Hat LINUX
(in response to Michael Levine)
Well, the fact you have 64GB of memory doesn't really come into play. What
are the sizes of your bufferpools and sheapthes? That will tell us how much
you are how much memory you are using. You can also run db2mtrk -i or d to
collect current DB2 memory usage, and also db2pd -osinfo. You didn't say
what release of Redhat you were on. Some releases of Redhat and SUSE
(Novell) need to be at a certain level to support setting instance memory to
automatic. You can check out the What's new and release notes for 9.5 and
they will tell you what level your OS needs to be at to support instance
memory(automatic). If however you are on a supported version of Redhat re:
instance memory set to automatic then you need to make sure your kernel
parms do not specify more memory than you have, if they do DB2 will try and
use it, and your instance and OS could crash. You may be running exact
queries but the access plans could be different because of any number of
reasons. What is the difference in access plan on the new? I have clients
running 9.5 on SUSE Linux, over 2,000 trans per sec no problem. The
performance on 9.5 has been better than expected. Sounds like you have
problems with your OS release or possibly other DB2 settings. I doubt the
query is using same access plan so it is not an apples to apples comparison.
If it is then I'd look at runstats first, any optimizer related changes and
general DB2 cfg parameter differences. Also, did you migrate from 8.2 to 9.5
or is the 9.5 install new? This will affect DBM CFG and DB CFG parameter
settings. PG



From: DB2 Data Base Discussion List [mailto:[login to unmask email] On Behalf
Of Levine, Michael
Sent: Thursday, January 08, 2009 5:41 PM
To: [login to unmask email]
Subject: [DB2-L] DB2 LUW 9.5 on 64bit Red Hat LINUX



Is anybody running DB2 LUW 9.5 (FP2a) on 64 bit Red Hat LINUX using 64GB of
memory on HP hardware? We are having performance problems that I can't
believe are actual bugs. First we cannot run with Instance memory set to
automatic (the server crashes). We have it capped at 32 GB to prevent
crashes. Now when we run a query with any WHERE predicate the performance
is terrible (when compared to the exact queries and data on 32 bit UDB 8.2).
It runs fine when there is no where predicate! IBM has been working with us
on this and all of our database configuration and instance level parms are
OK. I was wondering how many sites are running OK with this configuration?



Thanks,

Mike





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





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< http://idug.org/lsAU > IDUG 2009 - Australasia * 18-20 March * Melbourne,
Australia

< http://www.idug.org > IDUG.org was recently updated requiring members to
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______________________________________________________________________

* IDUG 2009 Rome, Italy * 5-9 October * http://IDUG.ORG/Events *
______________________________________________________________________



IDUG.org was recently updated requiring members to use a new password. You should have gotten an e-mail with the temporary password assigned to your account. Please log in and update your member profile. If you are not already an IDUG.org member, please register at http://www.idug.org/component/juser/register.html