Very bad FreeBSD SCSI RAID5 write speed performance

[Martin Blapp]

Hi,

> On Thu, Nov 13, 2003 at 06:38:53AM -0500, Gary Stanley wrote:
> > root at 64:[/tmp/blah]>dd if=/dev/zero of=/tmp/blah/blah
> > 89472+0 records in
> > 89471+0 records out
> > 45809152 bytes transferred in 8.546312 secs (5360108 bytes/sec)

Exactly what we get here: ~ 6MB per second with RAID5 and the IPS
driver. The Adaptec 3200s is similar.

A single disk has writes to the 53MB to the raw slice. I don't know
why 5 equal disks on 2 busses are that slow.

Martin