Date: Thu, 16 Apr 2009 10:47:23 +0200 (CEST) From: Alexander Best <alexbestms@math.uni-muenster.de> To: <utisoft@gmail.com>, Bruce Cran <bruce@cran.org.uk> Cc: freebsd-questions@freebsd.org Subject: Re: hard drive performance Message-ID: <permail-200904160847231e86ffa800001e4a-a_best01@message-id.uni-muenster.de> In-Reply-To: <b79ecaef0904150952v50fafd16k90c07ad521ff367d@mail.gmail.com>
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thanks guys. sorry for the newbie question. ;) Chris Rees schrieb am 2009-04-15: > 2009/4/15 Bruce Cran <bruce@cran.org.uk>: > > 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 > Hehe, I think everyone makes that mistake when they're enthusiastic > and sometimes even somewhat experienced. It's always such a > disappointment when they realise, I remember when I did too. > Chris
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