It isn't the stripe so much as the disk read block size. If your block size
is 8kb (which is common), then a sep of 32 means that every read against the
file will take 2 disk reads, whether or not you need it for the item you
want. Going to a sep of 128 would mean every read would take 8 physical disk
reads - the opposite of tuning.
RAID & striping by themselves help throughput; further tuning ignores the
disk setup.
If you have RAID0+1 for Unidata, you've made a good choice. Find out your
disk read/write block size (I would be astonished if it were 128K), and tune
your seperation for it.
Btw, if you have RAID5, you've made a poor choice for U2.
"Our greatest duty in this life is to help others. And please, if you can't
help them, could you at least not hurt them?" - H.H. the Dalai Lama
"When buying & selling are controlled by legislation, the first thing to be
bought & sold are the legislators" - P.J. O'Rourke
Dan Fitzgerald
From: "Chuck Mongiovi" <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: <[email protected]>
Subject: [U2] AIX disk performance and UniData
Date: Wed, 28 Sep 2005 17:02:41 -0400
Hey all,
I'm having some system performance issues and I was wondering if there's a
way to resize UniData files to take advantage of AIX system's striping ..
We have all of our logical volumes striped - one is 2 disks stripes, one is
3 disks .. they're both setup with a stripe size of 128k .. So - my
question
is if I raise the modulo on files with a MOD of less than 128 to 128 or 256
(prime of course) will I see a more even usage of my disks?
Does anyone have any experience with this at all?
-Chuck
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