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Date: Fri, 29 Dec 2006 06:30:14 -0800 (PST)
From: "R. B. Riddick" <arne_woerner@yahoo.com>
To: vd@FreeBSD.org
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Cc: freebsd-geom@freebsd.org
Subject: Re: gstripe performance scaling with many disks
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--- Vasil Dimov <vd@FreeBSD.org> wrote:
> On Fri, Dec 29, 2006 at 04:55:44AM -0800, R. B. Riddick wrote:
> In summary increasing the stripe size results in performance drop while
> increasing the number of read processes results in performance raise.
> (I also tested with stripe size 128*1024). My guess is that this is
> because raidtest often generates read requests with size less than the
> stripe size and then it reads from just one disk, or at most from
> several ones. It rarely (never?) generates a request that has read size
> 17*stripesize or greater so that all disks are used in parallel.
>
That is surprising for me... Small request size caused by raidtest shouldnt
decrease the performance so much, because u used 20 concurrent processes...

-Arne

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