Bowie Bailey wrote:
Joshua Baker-LePain wrote:
On Thu, 12 Oct 2006 at 4:22pm, Bowie Bailey wrote
I have two identical servers. The only difference is that the first
one has Maxtor 250G drives and the second one has Seagate 320G
drives.
OS: CentOS-4.4 (fully patched)
CPU: dual Opteron 280
Memory: 16GB
Raid card: 3ware 9550Sx-8LP
Raid volume: 4-disk Raid 5 with NCQ and Write Cache enabled
On the first server I have decent performance. Nothing spectacular,
but good enough. The second one has about 1/3 the write speed. I
can't find any difference between the systems. Both of them have
the same stripe size, both have ext3 filesystems, both have write
caching and NCQ turned on. I have already increased the read ahead
setting to 16384 on both servers.
Turn off NCQ. Last I knew, this was still 3ware's recommendation.
I can try that, but when I tested on the first server, I found that
disabling NCQ increased the read performance by 10M/s and decreased
the write performance by 10M/s. Maybe I'll get different results from
the Seagate drives.
Here's what I'm getting from a dual Opteron 275 box, Centos 4.4-64bit,
2gb RAM and an 8 drive array of 750gig Seagates:
Version 1.03 ------Sequential Output------ --Sequential Input-
--Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
/sec %CP
localhost.locald 4G 248901 96 138957 40 308874 42
625.8
I've been applying all the various tricks that came up during the last
couple of threads. Turning NCQ off definitely made a big difference for me.
Cheers,
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