Re: Performance of a software raid 5

[Johannes Segitz <johannes.segitz@gmail.com>]

On Tue, Apr 21, 2009 at 1:46 AM, John Robinson
<john.robinson@anonymous.org.uk> wrote:
> I would have thought it's because you're running in degraded mode and one in
> 3 sectors is having to be regenerated from the parity. It still seems a bit
> slow, though.

i don't think that that is a problem. The data is there without
redundancy so i can't see
how there would be the need to calculate anything

> I'm not quite sure whether I should be disappointed at my writes being so
> slow. Certainly there's a lot of rattling during writing, which probably
> indicates lots of seeks to write ext3's journal. But reads are roughly what
> I expected, at about three times the single-disc throughput.

200 MB/s reads would be nice but i expected quite a bit more speed
writing too. I know
that you don't get an O(n) speedup but falling behind the normal performance of
a single drive seems not okay.

Johannes
Btw.:The controller is on PCI-E so no bottleneck there