LinHES Forums
http://forums.linhes.org/

Increase RAID5 Write Performance
http://forums.linhes.org/viewtopic.php?f=3&t=19792
Page 1 of 1

Author:  mihanson [ Mon Apr 13, 2009 8:01 pm ]
Post subject:  Increase RAID5 Write Performance

I came across this post on the Gentoo forums and found it helped my software RAID5 write performance. I saw ~100% increase in my write performance over the default settings.

Check your write cache stripe size (Substitute for md0 if your array is something other than /dev/md0):
Code:
# cat /sys/block/md0/md/stripe_cache_size
256


Then try increasing it to 512, 1024, 2048, 2096, 8192:
Code:
# echo 512 > /sys/block/md0/md/stripe_cache_size


cd to your raid array (i.e. cd /path/to/mounted/raid5/array) and then benchmark performance. It's best to do this when your array is otherwise idle. I used an empty 15GB file to test.
Code:
# dd if=/dev/zero of=bigfile bs=1M count=15000 ; rm -f bigfile

and note the MB/s when it finishes. I found that a seting of 8192 was optimal for my array. Anything bigger saw diminishing returns.

Page 1 of 1 All times are UTC - 6 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/