I've read all the treads dealing with NSS performance issues and tried
every things suggested.

The read ahead trick worked perfect and I have good read performance.
I've updated the cciss module with version 2.6.10-1s from sourceforge
(HP doesn't provide one that match the last kernel).

I still have very poor write performance (around 8 KB/s).

The drive is a RAID1 with 2x300 HD.

Please ... help.