good performing SCSI RAID5 ( was: asr ( 2015S ) support in 5.4 amd64? )

[Dan Nelson]

In the last episode (Jun 01), Steven Hartland said:
> Thanks for that Bruce I'm quite surprised that these numbers are so
> low after playing with a cheapo hightech SATA controller which with
> the help of the guys on the list I was able to give out 200MB/s I
> really would expect the relatively expensive SCSI controllers to do
> significantly better especially as they have superior disks attached
> ( 10K vs 7k2 ) and not performance which is well below ( 1/2 ) that
> expected of a single disk.

The faster rpms will get you more concurrent I/Os per second but won't
do as much for throughput.  My asr 3200S cards got repurposed before I
could try them with 5.x, but with the 370F firmware I'm pretty sure I
was able to get more than 40MB/sec reads out of them on 4.x with 4-disk
RAID5 sets.  Since the asr driver needs Giant, try a UP kernel and see
if it goes any faster.
 
-- 
	Dan Nelson
	dnelson at allantgroup.com