Jeff,
> Let's say you had a server with 6 separate 15k RPM SCSI disks, what raid
> option would you use for a standalone postgres server?
>
> a) 3xRAID1 - 1 for data, 1 for xlog, 1 for os?
> b) 1xRAID1 for OS/xlog, 1xRAID5 for data
> c) 1xRAID10 for OS/xlong/data
> d) 1xRAID1 for OS, 1xRAID10 for data
> e) .....
>
> I was initially leaning towards b, but after talking to Josh a bit, I
> suspect that with only 4 disks the raid5 might be a performance detriment
> vs 3 raid 1s or some sort of split raid10 setup.
Knowing that your installation is read-heavy, I'd recommend (d), with the WAL
on the same disk as the OS, i.e.
RAID1 2 disks OS, pg_xlog
RAID 1+0 4 disks pgdata
--
--Josh
Josh Berkus
Aglio Database Solutions
San Francisco