[CentOS] Write performance with 3ware 9550

Mon Oct 16 20:24:13 UTC 2006
Bowie Bailey <Bowie_Bailey at BUC.com>

William L. Maltby wrote:
> On Fri, 2006-10-13 at 11:44 -0400, Bowie Bailey wrote:
> > Kirk Bocek wrote:
> > > <snip>
> > Right now, I am not looking for maximum performance.  I am just
> > trying to determine why there is a 3x difference in write
> > performance between two identical machines.
> 60 vs. 40 conductor cables on UDMA? have you wiggled/reseated them?

These are SATA drives, but I have checked the cable connections.

>  PS sizes similar and simailar load?

Identical PS.  Load should be similar.  Tests have been done at
runlevel 5 with nobody using the system.

> /var/log/messages BogoMips the same?

I'm not familiar with this.

> Mem config same?

Yep.  They've both got 16GB of RAM (6GB allocated to Huge Pages and
about 9GB free).

> Same "load". Does top in a "long" screen show any diference in number
> of loads or total load being imposed? Keep an eye out for excessive
> wait channels in top (have to change defaults of fields displayed and
> order) or in ps?

I haven't seen that.  I'll keep an eye on it next time.

> Are you using the sar reports, which can be helpful in the case of
> large unknowns.

I haven't used the sar reports.  Sar tends to be a bit cryptic.  If
you can give me a useful command line, I'll check it out.