Optimizing disk throughput on quad Opteron

Hello,

I'm working out specs for a new database server to be
purchased for our organization. The applications the
server will handle are mainly related to network
operations (monitoring, logging, statistical/trend
reports, etc.). Disk I/O will be especially high with
relation to processing network stats.

You can find a diagram of my initial
spec here:
http://img266.imageshack.us/img266/9171/dbserverdiagramuc3.jpg

Server will be a HP ProLiant DL585 G2 with four
dual-core 2.6GHz processors and 8GB of RAM.

I can always throw in more RAM. I'm trying to find
the most effective way to maximize disk throughput, as
the list archives suggest that it is the choke point
in most cases. I separated the storage into multiple
arrays on multiple controllers, and plan to have 512MB
RAM on each controller using BBWC. The plan is to
utilize multiple tablespaces as well as partitioned
tables when necessary. (Note that the
StorageWorks 4214R enclosure with Ultra3 disks is used
because we already have it lying around.)

I heard some say that the transaction log should be on
it's own array, others say it doesn't hurt to have it
on the same array as the OS. Is it really worthwhile
to put it on it's own array?

Can you guys see any glaring bottlenecks in my layout?
Any other suggestions to offer (throw in more
controllers, different RAID layout, etc.)? Our budget
limit is $50k.

Thanks!

P.S. I know there was a very similar thread started by
Ben Suffolk recently, I'd still like to have your
"eyes of experience" look at my proposed layout :-)

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