Date: Thu, 01 Jan 2009 22:21:29 -0800 From: Maxim Sobolev <sobomax@FreeBSD.org> To: Joel Jacobson <jjacobson@panasas.com> Cc: freebsd-current@FreeBSD.org Subject: Re: gstripe performance oddity Message-ID: <495DB269.5030803@FreeBSD.org> In-Reply-To: <3D76E927-AD4F-4B6E-83E8-44379814FD98@panasas.com> References: <3D76E927-AD4F-4B6E-83E8-44379814FD98@panasas.com>
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Joel Jacobson wrote: > i tried sending this to freebsd-geom but got no response, so i'll try a > higher traffic superset list... > > i have a bit of a weird issue, which i suspect is a configuration > problem, and was looking for a little advice. i have an LSI JBOD box > with a bunch of SAS drives that i would like to gstripe together. each > drive individually seems to be able to do about 80 MB/sec streaming > write, and doing parallel dd's gives me the 160 MB/sec i would expect. > if i gstripe them together with a 256k stripe width, i only see 80 > MB/sec, though. > > if, however, i newfs/mount it as ufs and then dd myself a big file, that > gets me about 120-130 MB/sec. > > why does mounting matter? You will see dd write speed increase on stripe only if you are using block size (bs=XX) larger than stripe size, so that you should try dd bs=512k or something and see if it helps. -Maxim
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