Date: Sat, 4 Nov 2006 21:55:42 +0100 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Oles Hnatkevych <don_oles@able.com.ua> Cc: freebsd-performance@freebsd.org Subject: Re: geom stripe perfomance question Message-ID: <20061104205542.GB83118@garage.freebsd.pl> In-Reply-To: <184686318.20061104222857@able.com.ua> References: <184686318.20061104222857@able.com.ua>
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[-- Attachment #1 --] On Sat, Nov 04, 2006 at 10:28:57PM +0200, Oles Hnatkevych wrote: > Hello all! > > I wonder why geom stripe works much worse than the separate disks that > constitute stripe. > > I have a stripe from two disks. Disks are on separate ATA channels. > > root# gstripe list > Geom name: bigdata > State: UP > Status: Total=2, Online=2 > Type: AUTOMATIC > Stripesize: 262144 > ID: 4233231544 > Providers: > 1. Name: stripe/bigdata > Mediasize: 500118323200 (466G) > Sectorsize: 512 > Mode: r1w1e1 > Consumers: > 1. Name: ad1 > Mediasize: 250059350016 (233G) > Sectorsize: 512 > Mode: r1w1e2 > Number: 0 > 2. Name: ad2 > Mediasize: 250059350016 (233G) > Sectorsize: 512 > Mode: r1w1e2 > Number: 1 > > Now let's read one of them and stripe. > > root# dd if=/dev/ad1 of=/dev/null bs=1m count=1000 > 1000+0 records in > 1000+0 records out > 1048576000 bytes transferred in 14.579483 secs (71921343 bytes/sec) > > root# dd if=/dev/stripe/bigdata of=/dev/null bs=1m count=1000 > 1000+0 records in > 1000+0 records out > 1048576000 bytes transferred in 15.882796 secs (66019610 bytes/sec) > > What I would expect is doubling the speed of transfer, not > slowing down. Am I wrong? Or is geom_stripe inefficient? > > I am running 6.2-PRERELEASE on Celeron 800. It should be, but first try something like: dd if=/dev/ad1 of=/dev/null bs=1m count=1000 &; dd if=/dev/ad2 of=/dev/null bs=1m count=1000 & -- Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.4 (FreeBSD) iD8DBQFFTP5OForvXbEpPzQRAhQXAKCsV/R15GqWtK57wItzNVsgK2MGLACgw57o oG5a8XnIkwlOaB1ftEBgdA4= =yDHV -----END PGP SIGNATURE-----
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