[CentOS] Write performance with 3ware 9550

[Bowie Bailey]

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.

-- 
Bowie