From owner-freebsd-questions@FreeBSD.ORG Tue Jan 6 10:21:16 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8D23D16A4CE for ; Tue, 6 Jan 2004 10:21:16 -0800 (PST) Received: from mail.business.allstream.net (tor-vs11.business.allstream.net [207.181.89.45]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0F57F43D1F for ; Tue, 6 Jan 2004 10:20:57 -0800 (PST) (envelope-from derek@cpainc.ca) Received: from derek ([66.46.154.210])i06IKtf1020093; Tue, 6 Jan 2004 13:20:55 -0500 (EST) Message-ID: <086401c3d481$d35e2ce0$0301a8c0@office.cpainc.net> From: "Derek Marcotte" To: "Mike Maltese" , References: <000201c3d461$eea71770$0301a8c0@office.cpainc.net> <012d01c3d47d$40fe8b50$f4f0a8c0@pcmedx.com> Date: Tue, 6 Jan 2004 13:20:55 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Subject: Re: Poor SCSI disk preformance X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 06 Jan 2004 18:21:16 -0000 > I wouldn't say that dd is the greatest benchmarking tool. You may want to > try benchmarks/rawio. I'll check that out just for kicks, but I _actually want_ to write zeros to the drive first, not just as a benchmark. The reasoning for this is that I'm trying to create a dedicated box to format HDDs in parallel. I wish to first zero the drives to make data recovery without an electron microscope difficult. Then, to test for bad sectors I do a checksum of the number of zero bytes written to disk, and then I read back from the disk and compare checksums. Not exactly an extensive test, and perhaps there is a verify option or trick in dd that I'm not aware of. I think that this would catch any blatantly bad drives... If not, there are 2 full disk operations that should be going faster. Actually, just for kicks: # dd if=/dev/da0 of=/dev/null bs=128k & [1] 1839 # iostat -K -w 1 da0 tty da0 cpu tin tout KB/t tps MB/s us ni sy in id 1 42 64.00 607 37.92 1 0 1 0 98 0 43 64.00 222 13.87 0 0 2 0 98 0 43 64.00 223 13.92 0 0 0 2 98 0 42 64.00 224 13.98 0 0 2 0 98 0 43 64.00 222 13.86 0 0 3 0 97 0 43 64.00 223 13.92 0 0 1 2 98 0 43 64.00 223 13.92 0 0 2 1 97 0 42 64.00 223 13.92 0 0 3 0 97 0 43 64.00 223 13.92 0 0 1 0 99 Seems to give me the performance that I expect... > Also, try monitoring diffferent types of transfers to > and from another physical disk with iostat. Actually, interestingly enough, when I copy a file, or do a newfs_msdos I only get 0.06-0.89MB/s transfers, which is what first tipped me off to the problems... Obviously less acceptable...