Re: (was: Re: md: raid5 vs raid10 (f2,n2,o2) benchmarks [w/10 raptors])

["Keld Jørn Simonsen" <keld@dkuug.dk>]

On Wed, Apr 02, 2008 at 01:49:44PM -0400, Justin Piszcz wrote:
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> On Wed, 2 Apr 2008, Justin Piszcz wrote:
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> >On Wed, 2 Apr 2008, Conway S. Smith wrote:

I have referenced both of your benchmaks in the wiki on performance. So
now I just hope that your URLs will live forever. I also took down some
of your recomendations there. 

I note that raid10,f2 has a much higher cpu load than raid10,n2 or
raid10,o2. How come? it is 31-38 % for f2, where n2 and o2 is around 15 %.

Also I note that the sequential read rate for o2 is nowhere near that of
n2, it is more like half of the n2 speed. I have seen claims from
normally trustworthy sources that o2 would obtain striping speeds.
IMHO theory would also say that o2 could not be striping.

And the optimized version from Justin impedes performance for f2, by
around 90 MB/s. How come?

best regards
keld