chrism@xxxxxxxxx wrote:
> 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.
With NCQ off, I get these results:
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
Second 50G 20853 8 41899 11 192713 23 116.9
1
Write performance increased by 2M/s and read performance decreased by 2M/s.
What tweaks have you applied so far? I would expect a 4-drive array
to be slower than an 8-drive array, but not this much!
--
Bowie
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