[Beowulf] posting bonnie++ stats from our cluster: any comments about my I/O performance stats?

Rahul Nabar rpnabar at gmail.com
Fri Sep 25 17:08:00 EDT 2009


On Fri, Sep 25, 2009 at 3:59 PM, Joe Landman
<landman at scalableinformatics.com> wrote:
> Looks like your IOP latency is around 50ms.  If you think about this, it
>  seems a little high, even for a RAID5.  I'll do some measurements here on
> our big units and we can compare.

Thanks again Joe!

About the latency:

It could have something to do with the fact that the overall latency
on our network has been pretty crappy (I believe). Round trip
ping-pong times in the 150 microsec range. Not sure.

> 466 IOP is ok ... basically 4 drives will give you this (5 RAID5 drives -> 4
> drives of data).  If you are IOP bound, you can do better, if this matters.

Sure, I'd have to figure out *iff* I  (or rather all my apps.) am IOP
driven. Not sure, I don't have a good answer for you. Of course, maybe
I am just missing a crucial simple step in figuring that out. Do let
me know.

On the other hand regarding our expansion plans: Our code is working
OK on this client that has the 466 IOPS. Ergo any larger
storage+network solution that can provide *at least* 466 IOPS ought to
work for us. Of course, assuming IOP is a good metric in the first
place. But that's back to the same point.

-- 
Rahul

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