Date: Sun, 5 Nov 2006 00:09:19 +0200 From: Oles Hnatkevych <don_oles@able.com.ua> To: freebsd-geom@freebsd.org Subject: geom stripe perfomance question Message-ID: <961295086.20061105000919@able.com.ua>
next in thread | raw e-mail | index | archive | help
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 tried to do the same with gvinum/stripe - the read speed was degraded too. And with gmirror depending on slice size speed was degraded differently. I am running 6.2-PRERELEASE on Celeron 800. -- Oles Hnatkevych mailto:don_oles@able.com.ua
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?961295086.20061105000919>