Date: Wed, 07 Jan 2009 04:05:24 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-geom@freebsd.org Subject: Re: performance problem with gstripe Message-ID: <gk1664$g6d$2@ger.gmane.org> In-Reply-To: <4AD370A6-2226-442F-BD80-8CFD4045B094@panasas.com> References: <4AD370A6-2226-442F-BD80-8CFD4045B094@panasas.com>
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[-- Attachment #1 --] Joel Jacobson wrote: > 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. How do you measure this? If with dd, what block size (bs) do you use? > > 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? I'd guess because of write caching that enables you to make use of multiple stripes at once, if your dd bs is smaller than 2*stripe size. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAklkG/QACgkQldnAQVacBcgANwCgkIv2J0Q1IlVS7IpqWrhVCRH+ Q38AoLW+L3QE8L390yw02URRWyEM1ivc =66OT -----END PGP SIGNATURE-----
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