On Wed, Sep 2, 2015 at 4:31 PM, Josh Berkus <josh@agliodbs.com> wrote:
> On 09/02/2015 02:25 PM, Tomas Vondra wrote:
>>
>> As I explained, spindles have very little to do with it - you need
>> multiple I/O requests per device, to get the benefit. Sure, the DBAs
>> should know how many spindles they have and should be able to determine
>> optimal IO depth. But we actually say this in the docs:
>
> My experience with performance tuning is that values above 3 have no
> real effect on how queries are executed.
That's the exact opposite of my findings on intel S3500 (see:
http://www.postgresql.org/message-id/CAHyXU0yiVvfQAnR9cyH=HWh1WbLRsioe=mzRJTHwtr=2azsTdQ@mail.gmail.com).
merlin
