PERC 4 performance

Herman Sheremetyev mlists at
Wed Apr 7 16:47:01 CDT 2004

Hi All,

My apologies for the cross-post.  I just installed Redhat EL 3 ES on a
Dell PowerEdge 2650 with a PERC 4/DC card (LSI PCI RAID controller) and
the performance seems no better than when I tried the PERC3 (Adaptec
onboard RAID controller).  I've played around with stripe size and other
various options while creating the arrays and I can't seem to get any
noticeable performance boost.  My best so far is about 22M/sec for
reading and around 20M/sec for writing, this is with 128K stripe size
and IO set to Cached.  These are pretty sad numbers to get from a top of
the line RAID controller and 5 10K RPM SCSI drives in RAID5.  In
comparison my laptop gets about 30M/sec reading speeds with 5400K RPM
IDE drive, and my 3ware IDE RAID controller performs even better on a
couple 7200K RPM drives in RAID1.  I've tried both the megaraid and
megaraid2 driver with no large difference between the two.

The tests I've tried are somewhat primitive, I've tried hdparm -t and
"cat /dev/sda > /dev/null" while running "vmstat 1".  Should I try some
other method to test this?  Any advice from anybody using these LSI RAID
cards on what kind of performance I should be expecting?  The
performance with software RAID on the same drives blows this card way
which seems very wrong to me.



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