Re: Bad iostat numbers

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.