From: Willeat, Todd (TWilleat@MHP.SMHS.COM)
Date: Mon Jul 22 2002 - 16:26:39 EDT
Make sure the write cache is enabled. Twice I had problems where the cache
became disabled and there was a noticable decrease in I/O (although not that
bad). The first time, the cache was replaced and that lasted for a few
weeks. The next time, the card was replaced and its been fine ever since.
Use scraidmgr -U -l 'scradi0' to check...
-----Original Message-----
From: L [mailto:leed@CHELE.CAIS.NET]
Sent: Monday, July 22, 2002 2:47 PM
To: aix-l@Princeton.EDU
Subject: 2498 Ultra3 and 2104 RAID5 configure performance very very bad
???
we have IBM P660 and AIX 4.3.3 O.S. on it. The P660 have 2498 Ultra SCSI3
RAID adapter card and connect seperate cables to 2104 disk array. We
configure 6 disks hardware RAID5 through "PDAM". while I load data from
LTO tape driver (high speed tape driver 15~30MB/sec) to this RAID5. the
performance is very very slow. Load 2Gb data toke 2hours to finish. I
use "topas" to check and found this RAID5 wrte speed is "550KByte/sec". I
called IBM support and support engineer told me nothing he can help.
Does anyone have expereince on it and can give me suggestion?
The configuration on 2498 RAID5 are:
6 disks raid 5
stripe size: 16K
command Queue Depth: 16
Thanks.
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