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.
John Allgood - ESC Systems Administrator
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