On Sun, 25 Jan 2009, M. Edward (Ed) Borasky wrote:
> Actually, this isn't so much a 'pgbench' exercise as it is a source of
> 'real-world application' data for my Linux I/O performance visualization
> tools. I've done 'iozone' tests, though not recently. But what I'm
> building is an I/O analysis toolset, not a database application.
Are these performance results when the analysis tools are active or
inactive? Have you investigated whether the analysis tools might be
slowing the I/O down at all?
> ...they told me that it was because the drive was re-ordering operations
> according to its own internal scheduler!
A modern SATA drive with native queuing will do that. SCSI drives have
been doing that for twenty years or so.
Matthew
--
I pause for breath to allow you to get over your shock that I really did cover
all that in only five minutes... -- Computer Science Lecturer