Alexander,
> Hmmm. Seems to me that this setup would be better than one RAID5 with three
> 36Gb disks, wouldn't you think so? With one RAID5 array, I would still have
> the data and the WAL on one volume...
Definitely. As I've said, my experience with RAID5 is that with less than 5
disks, it performs around 40% of a single scsi disk for large read-write
operation on Postgres.
If you have only 3 disks, I'd advocate one disk for WAL and one RAID 1 array
for the database.
--
Josh Berkus
Aglio Database Solutions
San Francisco