Re: SSD + RAID

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Scott Marlowe wrote:
On Thu, Nov 19, 2009 at 10:01 AM, Merlin Moncure <mmoncure@xxxxxxxxx> wrote:
pgbench is actually a pretty awesome i/o tester assuming you have big
enough scaling factor
Seeing as how pgbench only goes to scaling factor of 4000, are the any
plans on enlarging that number?
I'm doing pgbench tests now on a system large enough for this limit to matter, so I'm probably going to have to fix that for 8.5 just to complete my own work.

You can use pgbench to either get interesting peak read results, or peak write ones, but it's not real useful for things in between. The standard test basically turns into a huge stack of writes to a single table, and the select-only one is interesting to gauge either cached or uncached read speed (depending on the scale). It's not very useful for getting a feel for how something with a mixed read/write workload does though, which is unfortunate because I think that scenario is much more common than what it does test.

--
Greg Smith    2ndQuadrant   Baltimore, MD
PostgreSQL Training, Services and Support
greg@xxxxxxxxxxxxxxx  www.2ndQuadrant.com


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