| From: | Greg Smith <greg(at)2ndquadrant(dot)com> |
|---|---|
| To: | Ivan Voras <ivoras(at)freebsd(dot)org> |
| Cc: | Janning <ml(at)planwerk6(dot)de>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Disk performance |
| Date: | 2010-06-15 18:07:57 |
| Message-ID: | 4C17C17D.8070404@2ndquadrant.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
Ivan Voras wrote:
> (or if you are looking at raw numbers: a 15,000 RPM drive will sustain
> 15000/60=250 random IOs per second (IOPS)
That's only taking into account the rotation speed--a 15K drive can do
250 physical commits per second if you never seek anywhere. A true IOPS
number also considers average seek latency. A decent 15K drive will be
around 4ms there, which makes for 167 IOPS total.
Random note: this discussion is on the wrong list. There are more
people interested in this topic who post regularly on pgsql-performance
than pgsql-general.
--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.us
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