Poweredge 800 multi-disk SATA slowdown?
blc at redhat.com
Tue Jul 26 13:54:36 CDT 2005
Does anybody else have a Poweredge 800 with multiple SATA drives? I'm
running Fedora Core 4 and seeing some unexpected bottlenecks when
accessing multiple drives at one time.
There are 4 drives in my system. If I do a raw read for 10G of any
single drive, the sustained transfer rate is about 55MB/s. Very nice.
The odd thing is, if I do a raw read of any two drives, 10G each, the
sustained transfer rate of each drive is only about 27MB/s. Likewise,
reading 4 drives in parallel always tops out at around 13MB/s per drive.
Would you expect this?
I know this isn't an all-inclusive benchmark like Bonnie++ or IOZone,
but it's akin to the workload this particular system does.
This is with a 2.6.12 kernel and the ata_piix driver using the 4 port
Any advice or insight appreciated.
-Brendan (blc at redhat.com)
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