On Sat, 12 May 2007, Bertrand Renuart wrote:
> I always have been told (S/P)ATA disks should somehow be avoided in server
> systems. This mainly because the high rate of interrupt requests generated
> by the IO subsystem will constantly interrupt the CPU which then becomes
> unavailable for other server tasks. SCSI disks should be preferred mainly
> for that reason.
>
> Can someone confirm this statement?
The interrupt rate has nothing to do with the type of disk, and a lot to
do with the controller. There is a CPU difference between $50
consumer IDE/SATA adapters, and $300 server grade IDE/SATA adapters.
You'll want the controller to support fast DMA at minimum.
> FYI, we have to upgrade one of our development machine - hence the question.
> This machine is mainly used to run unattended software builds -> moves large
> quantity of small files and requires lots of CPU.
However, even the $50 adapters are way faster than what you could get
10 years ago. I would start with a higher end $50+ adapter (you want
it reliable). If you get a lot of "system" CPU time during heavy disk
IO, then the $300 adapter will relieve that. For example, a super cheap
ATA adapter was giving us 25% system CPU on backups on a 1.8Ghz Celeron.
Replacing that with a more expensive (but < $100) IDE adapter reduced
system time to 1% or so.
--
Stuart D. Gathman <stuart@bmsi.com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.
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