On Fri, 2006-02-10 at 11:24 +0100, Markus Schaber wrote:
> For lots non-read-only database workloads, RAID5 is a performance
> killer. Raid 1/0 might be better, or having two mirrors of two disks
> each, the first mirror holding system, swap, and the PostgreSQL WAL
> files, the second one holding the data.
I was under the impression that it is preferable to keep the WAL on
its own spindles with no other activity there, to take full advantage
of the sequential nature of the WAL writes.
That would mean one mirror for the WAL, and one for the rest.
This, of course, may sometimes be too much wasted disk space, as the WAL
typically will not use a whole disk, so you might partition this mirror
into a small ext2 filesystem for WAL, and use the rest for files seldom
accessed, such as backups.
gnari
