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Date: Thu, 16 Apr 2009 10:47:23 +0200 (CEST)
From: Alexander Best <alexbestms@math.uni-muenster.de>
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Organization: Westfaelische Wilhelms-Universitaet Muenster
To: <utisoft@gmail.com>,
 Bruce Cran <bruce@cran.org.uk>
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Cc: freebsd-questions@freebsd.org
Subject: Re: hard drive performance
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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