Re: Re: index and data tablespaces on two separate drives or one RAID 0?

On Fri, Jul 6, 2012 at 8:51 PM, ach <alanchines(at)gmail(dot)com> wrote:

> > My fastest postgresql servers have everything on one raid10, using 16 or
> > 20 15000 rpm SAS2 drives on a 1gb flash-backed cache controller.
>
> Thank you - that affirms what'd been my own growing supposition, and the
> plan
>
> > why?
>
> Really? ...Well, I mean, I'd just been going with what I'd seen asserted
> as
> the solid baseline position: WAL should be on its own separate drive,
> devoid of any interference and/or interruption other than just writing WAL.
> To see that challenged is surprising; are you saying my interpretation on
> that point would be incorrect, and that assumption would be wrong?
>
> Thank you again for your feedback!
>
>
I wouldn't make any assumptions, and benchmark various configurations using
your hardware and your data usage pattern. Sometimes "common knowledge"
doesn't apply to your specific problem.

http://www.slideshare.net/selenamarie/what-assumptions-make-filesystem-io-from-a-database-perspective