SUMMARY: wait io and SAN

From: <>
Date: Thu Feb 13 2003 - 04:36:09 EST

thanks all who replied.

Darren Dunham pointed out,  that wait io on a system with

fast disks doesnt mean that the amount of requested io is very high

so the disks are not slow.

joe fletcher reported about a similar experience but they found out

that the reporting tool did wrong reporting instead of the disks being slow

I read a similar thing on the internet pointing to mpstat not reporting

Some pointed to the hba and and said to get a new driver update.

Others reminded that parallel to tuning the san side you can tune

the oracle side. On is a good paper on the aspects of

tuning oracle in a san enviroment.

the tool to use is iostat to see the amount of wait queue and the

percentage of disk usages. on the san side this would be




                      Gesendet von:            Kopie:                                                   
                      sunmanagers-admin@sunm   Thema:    wait io and SAN                                
                      12.02.2003 13:38                                                                  


we have a 12 CPU Server with a oracle database running on it
OS: 5.8
SAN: EMC Symmetrix
HBA: Emulex
when running batch jobs we experience high values of wait io
on all CPU's (20 - 60 % using mpstat). The amount for every single CPU is
about the same.
Performance checks on the SAN side didn't show any performance

I would have thought that SAN disks would have a better performance than
Has anyone a similar experience or information about finding the cause
of the wait io?

thanks in advance,
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Received on Thu Feb 13 04:41:39 2003

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