Peformance Tuning Opterons/ Hard Disk Layout

Hello Again

In the below statement you mention putting each database on its own raid
mirror.

"However, sticking with your arrangement, it would seem that you might be
able to get some extra performance if each database is on it's own raid,
since you are fairly likely to have 2 transactions occuring at the same
time, that don't affect eachother (since you wouldn't have any foreign
keys, etc on 2 separate databases.)"

That would take alot of disk drives to accomplish. I was thinking maybe
putting three or four databases on each raid and dividing the heaviest
used databases on each mirrored set. And for each of these sets have its
own mirror for pg_xlog. My question is what is the best way to setup
postgres databases on different disks. I have setup multiple postmasters
on this system as a test. The only problem was configuring each
databases "ie postgresql.conf, pg_hba.conf".  Is there anyway in
postgres to have everything in one cluster and have it seperated onto
multiple drives. Here is a example of what is was thinking about.

MIRROR1 - Database Group 1
MIRROR2 - pg_xlog for database group 1
MIRROR3 - Database Group 2
MIRROR4 - pg_xlog for database group 2
MIRROR5 - Database Group 3
MIRROR6 - pg_xlog for database group 3

This will take about 12 disk drives. I have a 14 bay Storage Bay I can
use two of the drives for hotspare's.




Thanks

John Allgood - ESC
Systems Administrator