Date: Wed, 15 Apr 2009 17:52:38 +0100 From: Chris Rees <utisoft@googlemail.com> To: Bruce Cran <bruce@cran.org.uk> Cc: Alexander Best <alexbestms@math.uni-muenster.de>, freebsd-questions@freebsd.org Subject: Re: hard drive performance Message-ID: <b79ecaef0904150952v50fafd16k90c07ad521ff367d@mail.gmail.com> In-Reply-To: <20090415140841.37ad038b@gluon.draftnet> References: <permail-20090415115413f0889e8400007ff5-a_best01@message-id.uni-muenster.de> <20090415140841.37ad038b@gluon.draftnet>
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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 -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
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