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From: Craig Boston <craig@meoqu.gank.org>
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Date: 31 Mar 2003 15:55:44 -0600
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cc: FreeBSD Stable List <freebsd-stable@freebsd.org>
Subject: Re: vinum performance
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On Mon, 2003-03-31 at 15:41, Jason Andresen wrote:
> (Both of these were on previously untouched files to prevent any 
> caching, and the "write" test is on a new file, not rewriting an old one)
> Write speed:
> 81920000 bytes transferred in 3.761307 secs (21779663 bytes/sec)
> Read speed:
> 81920000 bytes transferred in 3.488978 secs (23479655 bytes/sec)
> 
> But on the RAID5:
> Write speed:
> 81920000 bytes transferred in 17.651300 secs (4641018 bytes/sec)
> Read speed:
> 81920000 bytes transferred in 4.304083 secs (19033090 bytes/sec)

Disclaimer: IANAVE (I am not a Vinum Expert)

What block size are you using with dd?  If your bs= is less than your
RAID stripe size, it seems like it would end up doing unnecessary
read-modify-write cycles...

Craig