[CentOS] Write performance with 3ware 9550

William L. Maltby CentOS4Bill at triad.rr.com
Mon Oct 16 21:05:52 UTC 2006

On Mon, 2006-10-16 at 16:24 -0400, Bowie Bailey wrote:
> William L. Maltby wrote:
> > On Fri, 2006-10-13 at 11:44 -0400, Bowie Bailey wrote:
> > > Kirk Bocek wrote:
> > > > <snip>

WOW! Do I have a typo bug or what?

> > 
> > > 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.
> <snip>

> > /var/log/messages BogoMips the same?
> I'm not familiar with this.

In /var/log/messages (and dmesg too, IIRC) is a "rating" of performance
for the CPU. "BogoMIPS" is the name. Also in there is "Detected xxxx.x
MHz processor". I was thinking if there is any substantial difference,
maybe that is a clue.

E.g. if PS is weak, one of the processors may run slow. I just finished
chasing some junk caused by a weak PS. AMD 2200+, s/b 1.8GHz, was
running 1.38GHz.

Popped in a 575 watt (425 continuous) PS and all is good again.

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

In BIOS, same timings on memory (CAS, etc.)?

> > 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.

It has been so long since I did admin jobs for real, I can't help you.
But there's lots of strong admins here.

Guys/gals, help the man out here?

> Thanks!

Sorry I can't be more help. I just acquired my first two SATA drives and
have yet to install and start using them.

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