Re: SSA vs SCSI - general IO troubleshooting
From: Patrick B. O'Brien (pobrien_at_DOIT.NV.GOV)
Date: 03/24/05
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Date: Thu, 24 Mar 2005 09:02:07 -0800 To: aix-l@Princeton.EDU
I/O seems to be the bottleneck for me, mostly.
You might look at 5L's migratelp.
You'd first run lvmstat -e -v vg_name to find your hotspots.
The man for these looks good.
________________________________
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of
Mark Schlechte
Sent: Thursday, March 24, 2005 8:46 AM
To: aix-l@Princeton.EDU
Subject: SSA vs SCSI - general IO troubleshooting
I'm trying to figure out what kind of performance differences there are
between good ol SSA compared to some SCSI Ultra 320 disks or even if
that is my problem.
Server A is a 6-way 6F1 668MHZ, 8GB ram with a number of internal SSA
disks and 13 oracle databases.
The disk is a mix of some RAID5, and RAID1 over 2 adapters.
Server B is a 2-way 6C3 1.2GHZ, 2GB ram with 6 SCSI disks and 4 oracle
databases.
This disk is just JBOD using a single 6203 SCSI adapter.
Due to oracle licensing costs we are moving one of the databases off the
6F1 onto the 2-way 6C3.
Our testing indicates very high I/O rates on the SCSI disk and tasks
take way to long to complete.
I'm wondering where I should focus my effort on trying to aleviate the
disk I/O bottleneck.
Is it SSA vs SCSI, the adapter (cache on the SSA adapter), more memory,
should I look at vmtune settings, etc.
I did run filemon while testing was going on.
CPU utilization is 67.7%
Most active Segments (all page table entries)
Most Active Physical Volumes (all hdisks show util 1.00)
Lots of questions I know, just looking for any general comments on where
people would start first.
Mark
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