PERC 4/SC write performance

[Marcus Williams]

Hi -

We recently bought a poweredge server with a PERC 4/SC card in it. The 
write performance under linux is abysmal (RAID 5/reiserfs) - its 
basically in the default configuration, is there anything I can change 
to bump the performance that wont blow away my drive configuration?

I'm willing to risk enabling the write-back cache as its on a UPS and 
has redundant PSUs but I cant work out if this will destroy anything. I 
tend to leave RAID setups well alone once they're working but I've 
always used s/w raid until this server.

Thanks

Marcus