Re: more 10K disks or less 15K disks

With the increase in the number of disks that we can afford to have in
1 box..we will definitely plan on having WAL on dedicated disks.
Previously..we were stuck with the chassis limitation of 6 disks per
box.

On Thu, Apr 29, 2010 at 12:25 PM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:
> On Thu, Apr 29, 2010 at 11:26 AM, Anj Adu <fotographs(at)gmail(dot)com> wrote:
>> All the disks are usually laid out in a single RAID 10 stripe . There
>> are no dedicated disks for the OS/WAL as storage is a premium
>
> You should at least investigate the performance difference of having a
> separate volume for WAL files on your system.    Since WAL files are
> mostly sequential, and db access is generally random, the WAL files
> can run really quickly on a volume that does nothing else but handle
> WAL writes sequentially.  Given the volume you're handling, I would
> expect that storage is not any more important than performance.
>
> The fact that you're asking whether to go with 12 or 24 600G disks
> shows that you're willing to give up a little storage for performance.
>  I would bet that the 24 10k disks with one pair dedicated for OS /
> pg_xlog would be noticeably faster than any single large volume config
> you'd care to test, especially for lots of active connections.
>