very poor performance of LSILogic's SATA 150-6D (RAID5)

[Mikhail Teterin]

Hello!

We are observing very low performance of the 5- and 6-drive RAID5 array on the 
LSILogic.

For formal comparision we created two logical drives -- a 5-drive RAID5 and a 
1-drive RAID0. (All 6 disks are identical 200Gb Western Digital).

According to iozone, the 5-drive RAID5 gets from 3 to 8 Mb/s. The 1-drive 
RAID0 goes from 20 to 50Mb/s.

Now, the controller has no battery and thus is not allowed to cache much, but 
is the difference really supposed to be so great? It has 5 disks at its 
disposal, after all...

	-mi