Peformance Tuning Opterons/ Hard Disk Layout

Hello All

I am setting up a hardware clustering solution. My hardware is Dual
Opteron 550 with 8GB ram. My external storage is a Kingston Fibre
channel Infostation. With 14 15000'k 36GB drives. The OS we are running
is Redhat ES 3.0. Clustering using Redhat Cluster Suite. Postgres
Version is Postgres 7.4.7. We will be setting up about 9 databases which
range in size from 100MB to 2.5GB on the config. The postgres
application is mostly read intensive. What would be the best way to
setup the hardrives on this server. Currently I have it partioned with 2
seperate raid 5 with 1 failover per raid. I have two database clusters
configured with a seperate postmaster running for each. Running two
postmasters seems like a pain but that is the only way I knew to
seperate the load. I am mostly concerned about disk IO and performance.
Is my current setup a good way to accomplish the best performance or
would it be better to use all the drives in one huge raid five with a
couple of failovers. I have looked around in the archives and found some
info but I would like to here about some of the configs other people are
running and how they have them setup.

Thanks

John Allgood - ESC
Systems Admin