Hi Miles, Paul Zarnowski and others who responded to my question!
Just to let you know the status of my performance problem: we converted the
database RAW LV's to JFS and we enabled AIO and direct I/O. This caused CPU
wait to go down from an average of 40% to about 25%. Sequential I/O rate
measure outside of TSM went up from 10 Mb./sec. to around 40 Mb./sec.
But TSM does not benefit from this at all. We checked everything outside of
TSM, so I will now create a software call at IBM. The database itself has to
be the bottleneck.
Again, thank you VERY much for all your help!!!
Kindest regards,
Eric van Loon
KLM Royal Dutch Airlines
-----Original Message-----
From: Miles Purdy [mailto:purdym AT FIPD.GC DOT CA]
Sent: Wednesday, February 02, 2005 19:04
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: SSA Disk performance
Hi Eric,
I'd like to help you out.
Check this out first:
http://www.samag.com/documents/s=1146/sam0109j/0109j.htm
And maybe contact me offline and I will see what I can do.
Miles
----------------------------------------------------------------------------
------------------
Miles Purdy
System Manager
Information Systems Team (IST),
Farm Income Programs Directorate (FIPD),
Agriculture and Agri-Food Canada (AAFC)
6th Floor 200 Graham Ave. Mailing: PO box 6100
Winnipeg, MB, CA R3C 4N3
R3C 4L5
Office contact: Mobile contact:
purdym AT fipd.gc DOT ca
purdym AT rogers.blackberry DOT net
ph: (204) 984-1602 fax: (204) 983-7557 Cell: (204) 291-8758
"If you hold a UNIX shell up to your ear, can you hear the C?"
----------------------------------------------------------------------------
---------------------
>>> Eric-van.Loon AT KLM DOT COM 02-Feb-05 10:39:19 AM >>>
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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