ADSM-L

SSA Disk performance

2005-02-02 11:39:10
Subject: SSA Disk performance
From: "Loon, E.J. van - SPLXM" <Eric-van.Loon AT KLM DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 2 Feb 2005 17:39:19 +0100
Hi *SM-ers!
We are currently struggling with our SSA disk performance.
For some strange reason we see that although all disks use LVM mirroring,
the reads are not balanced. In most case one disk is used for 60 or 70%
while it's mirror is just using 3%.
We also measured the disks performance. We created a file on a raw logical
volume and measured around 15 Mbytes/sec. We created a JFS filesystem on the
same disks and reran the test: 40 Mbytes/sec. I cannot explain this
difference! RAW should perform better that JFS on AIX 4.3.3, right?
Today we upgraded AIX to the latest maintenance level (11) and installed the
latest firmware on the disks, but performance hasn't improved.
I was hoping that TSM-ers with AIX performance knowledge can help me out
here, I'm stuck right now...
Thank you VERY much in advance for any reply!!
Kindest regards,
Eric van Loon
KLM Royal Dutch Airlines


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