Date: 21 Dec 1999 10:42:18 -0700 From: Dale Hagglund <rdh@best.com> To: freebsd-questions@freebsd.org Subject: Re: when is it safe to use the 0xa0ffa0ff disk flags? Message-ID: <86so0w5gxx.fsf@ponoka.battleriver.com> In-Reply-To: Jonathon McKitrick's message of "Tue, 21 Dec 1999 16:05:26 %2B0000 (GMT)" References: <Pine.BSF.4.21.9912211604160.43375-100000@dogma.freebsd-uk.eu.org>
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Jonathon McKitrick <jcm@dogma.freebsd-uk.eu.org> writes:
> Hod do you measure these figures? With iozone? Is there a simple
> method to run this program that gives newbie-intelligible results?
I just ran
time dd if=/dev/zero of=100m bs=1m count=100
after rebooting to get the write speed. For the read speed, I
switched the ``if'' and ``of'' values. (I just realized that I should
have used /dev/null for the output file, but it looks like /dev/zero
just throws away any stuff you write to it.)
I ran each test a few times, and then averaged the reported clock
times. dd itself reports a bytes/second figure, but I just did 100 /
average-time to get the MB/s numbers I quoted.
I'm sure there are more precise methods of measuring i/o speed, but to
detect a 3x speedup this is easily accurate enough. I've never tried
iozone, so I don't know what's wonderful or not so wonderful about it.
Dale.
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