* Setting NR_STRIPES high increases RAID5 performance
@ 2005-09-21 9:33 bart
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From: bart @ 2005-09-21 9:33 UTC (permalink / raw)
To: linux-raid@vger.kernel.org
Hi,
When testing a soft RAID5 (8 SATA drives, Marvell chip) with iometer I noticed
that the read performance did drop much less when adding randomness to the drive
access as the write performance (read 80MB/s->40MB/s, write 70MB/s->9MB/s). Such a
difference I can't explain by the read-compute-write of the parity stripe.
I found that increasing NR_STRIPES from 256 to (8*1024) did increase the throughput
for write from 9MB/s to 35 MB/s. This is still less as I would expect from 8
SATA disks in parallel. Could it be the raid5d thread is not waken up enough
or has not enough priority? Anybody knows any other #defines that could help
here?
Bart
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