From owner-freebsd-questions Tue Dec 21 9:42:26 1999 Delivered-To: freebsd-questions@freebsd.org Received: from lh2.rdc1.ab.home.com (ha1.rdc1.ab.wave.home.com [24.64.2.50]) by hub.freebsd.org (Postfix) with ESMTP id 6F16F14EE0 for ; Tue, 21 Dec 1999 09:42:24 -0800 (PST) (envelope-from rdh@best.com) Received: from best.com ([24.66.216.246]) by lh2.rdc1.ab.home.com (InterMail v4.01.01.00 201-229-111) with ESMTP id <19991221174220.MRGU15713.lh2.rdc1.ab.home.com@best.com> for ; Tue, 21 Dec 1999 09:42:20 -0800 Received: (from rdh@localhost) by best.com (8.9.3/8.8.5) id KAA01691; Tue, 21 Dec 1999 10:42:18 -0700 (MST) To: freebsd-questions@freebsd.org Subject: Re: when is it safe to use the 0xa0ffa0ff disk flags? References: From: Dale Hagglund Date: 21 Dec 1999 10:42:18 -0700 In-Reply-To: Jonathon McKitrick's message of "Tue, 21 Dec 1999 16:05:26 +0000 (GMT)" Message-ID: <86so0w5gxx.fsf@ponoka.battleriver.com> Lines: 23 User-Agent: Gnus/5.070098 (Pterodactyl Gnus v0.98) Emacs/20.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Jonathon McKitrick 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. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message