On Wed, Mar 13, 2013 at 7:26 AM, Shaun Thomas <sthomas@optionshouse.com> wrote:
> On 03/12/2013 05:49 PM, Gregg Jaskiewicz wrote:
>
>> So out of 6 disks then having 4 in Raid 1+0 configuration and other
>> two in mirror for WAL. That's another option then for me to test.
>
>
> That is an option, but it's not necessarily a good one. If all you have are
> six disks, you are probably better off just doing a big RAID-10 for
> everything.
When you've got a smallish number of drives, one big RAID-10 should be
the starting point, and until benchmarks or testing show otherwise
it's usually the best answer.
Note that due to some issues with fsync (esp on ext2/3 partitions) it
is often STILL useful to make a separate partition on that one big
RAID-10 for pg_xlog to live on.
The only real exception to one big RAID-10 on a smallish number of
disks is an almost read only database. In that case using a RAID-5
might be acceptable for the greater amount of storage you can get.
Something like a log analysis or reporting db for instance.