Re: Disk performance

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@2ndQuadrant.com   www.2ndQuadrant.us