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SubjectRe: limits on raid
david@lang.hm wrote:
> I plan to test the different configurations.
>
> however, if I was saturating the bus with the reconstruct how can I fire
> off a dd if=/dev/zero of=/mnt/test and get ~45M/sec whild only slowing
> the reconstruct to ~4M/sec?
>
> I'm putting 10x as much data through the bus at that point, it would
> seem to proove that it's not the bus that's saturated.

I am unconvinced. If you take ~1MB/s for each active drive, add in SCSI
overhead, 45M/sec seems reasonable. Have you look at a running iostat
while all this is going on? Try it out- add up the kb/s from each drive
and see how close you are to your maximum theoretical IO.

Also, how's your CPU utilization?

--
Brendan Conoboy / Red Hat, Inc. / blc@redhat.com
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