Date: Wed, 15 Apr 2009 14:08:41 +0100 From: Bruce Cran <bruce@cran.org.uk> To: Alexander Best <alexbestms@math.uni-muenster.de> Cc: freebsd-questions@freebsd.org Subject: Re: hard drive performance Message-ID: <20090415140841.37ad038b@gluon.draftnet> In-Reply-To: <permail-20090415115413f0889e8400007ff5-a_best01@message-id.uni-muenster.de> References: <permail-20090415115413f0889e8400007ff5-a_best01@message-id.uni-muenster.de>
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On Wed, 15 Apr 2009 13:54:13 +0200 (CEST) Alexander Best <alexbestms@math.uni-muenster.de> wrote: > hi there, > > i have 2 hard drives running. the first one is SATA300 and the other > one UDMA100. here are the dmesg entries: > > ad0: 238474MB <SAMSUNG SP2504C VT100-50> at ata0-master SATA300 > ad1: 157066MB <Hitachi HDS722516VLAT80 V34OA63A> at ata4-master > UDMA100 > > i've tried to test the drives' performances using the following > commands: > > dd if=/dev/ad0 of=/dev/null bs=1m count=300 > and > dd if=/dev/ad1 of=/dev/null bs=1m count=300 > > the results are: > ad0 = 314572800 bytes transferred in 4.325645 secs (72722751 > bytes/sec) ad1 = 314572800 bytes transferred in 5.166126 secs > (60891430 bytes/sec) > > the results for ad0 are a bit disappointing though. is this normal or > is bs=1m wrong? 70MB/s is a very good transfer rate for a hard drive. The 300MB/s rate refers to the maximum the physical interface can support, but drives never get close to that because they can't read from disk at that speed. -- Bruce Cran
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