Re: Bad iostat numbers - Mailing list pgsql-performance

From Scott Marlowe
Subject Re: Bad iostat numbers
Date
Msg-id 1165250254.14565.333.camel@state.g2switchworks.com
Whole thread Raw
In response to Re: Bad iostat numbers  (Scott Marlowe <smarlowe@g2switchworks.com>)
List pgsql-performance
On Mon, 2006-12-04 at 10:25, Scott Marlowe wrote:
>
> OTOH, with the choice at my last place of employment being LSI or
> Adaptec, LSI was a much better choice.  :)
>
> I'd ask which LSI megaraid you've tested, and what driver was used.
> Does RHEL4 have the megaraid 2 driver?

Just wanted to add that what we used our database for at my last company
was for lots of mostly small writes / reads.  I.e. sequential throughput
didn't really matter, but random write speed did.  for that application,
the LSI Megaraid with battery backed cache was great.

Last point, bonnie++ is a good benchmarking tool, but until you test
your app / postgresql on top of the hardware, you can't really say how
well it will perform.

A controller that looks fast under a single bonnie++ thread might
perform poorly when there are 100+ pending writes, and vice versa, a
controller that looks mediocre under bonnie++ might shine when there's
heavy parallel write load to handle.

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