I have a LSI MegaRAID i4 running in RAID 5 mode with 4 x 120 GB ATA drives as my "/home" partition. The write performance is deplorably bad (5 MB/s) but what's worse is that the system load shoots up to 15.0 or even higher when I transfer any file that takes longer than a couple of seconds. The system has quite a bit running on it (usually around 100 processes), but the load normally averages around 0.02 - 0.8 (when not transerferring files).
Try adding elevator=deadline to your kernel line in /etc/grub.conf and reboot.
This certainly helped. The transfer speed is up a little (~ 7 MB/s) and the system load is down to ~ 5.75. This is a marked improvement, but the load still seems a bit high and the write speed a bit low.
Is it just that this card is crap?
I have a different server with a single PIII 533 MHz, 384 MB RAM, and 2 x 80 GB drives in a software RAID 1. On this box, the load barely ever goes above 1.5, and the write speed is closer to 30 MB/s. This system has only about 2/3 the number of processes of my problem box, but the performance differences are very noticeable.
-- Chris Stark Musician, Linux User, Grad Student http://chrisstark.com
