From owner-freebsd-questions@FreeBSD.ORG Sun Aug 24 17:32:03 2003 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 15E5116A4BF for ; Sun, 24 Aug 2003 17:32:03 -0700 (PDT) Received: from falcon.midgard.homeip.net (h76n3fls20o913.bredband.comhem.se [213.67.148.76]) by mx1.FreeBSD.org (Postfix) with SMTP id 1487243F85 for ; Sun, 24 Aug 2003 17:32:01 -0700 (PDT) (envelope-from ertr1013@student.uu.se) Received: (qmail 74704 invoked by uid 1001); 25 Aug 2003 00:31:58 -0000 Date: Mon, 25 Aug 2003 02:31:58 +0200 From: Erik Trulsson To: Chris Newman Message-ID: <20030825003158.GA72370@falcon.midgard.homeip.net> Mail-Followup-To: Chris Newman , freebsd-questions@FreeBSD.ORG References: <000001c36a95$bdd637b0$0300a8c0@owl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000001c36a95$bdd637b0$0300a8c0@owl> User-Agent: Mutt/1.5.4i cc: freebsd-questions@FreeBSD.ORG Subject: Re: hard disk performance issue 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: Mon, 25 Aug 2003 00:32:03 -0000 On Sun, Aug 24, 2003 at 06:16:11PM -0500, Chris Newman wrote: > Hi, > > I have a Dell P3-500 Optiplex GX1. I was running FreeBSD 5.0 on an 8G drive. > I recently upgraded to a Western Digital ATA100 40GB drive and loaded > FreeBSD 5.1. > I expected to get improved drive performance, however, my motherboard would > only do UDMA-33. > > So, I picked up a Maxtor SATA/150 PCI Combo card. It's supposed to do > ATA-100. My dmesg > indicates that it is running UDMA-100, but my disk dump performance is still > pathetic. > > Here's a dd sample: > > tigger# dd if=/dev/ad8s1d of=/home/chris/tmp.dat count=10000 > 10000+0 records in > 10000+0 records out > 5120000 bytes transferred in 2.292473 secs (2233396 bytes/sec) > > ~ 2MB per second?? It was about 1.8MB per second before I upgraded. The only > thing > I can attribute the marginal speed-up to is the faster drive rotation speed > (7400 RPM). What do you expect when you only transfer 512 bytes with each read/write? That is a lot of overhead, and will make the actual speed of the disk to have little effect on the numbers obtained. Try increasing the block size. I.e. try: dd if=/dev/ad8s1d of=/home/chris/tmp.dat bs=64k count=100 On my system that gives about a factor of 8 faster performance. To get a better idea on how fast the disk actually is (with less overhead from the filesystem, and with less seeking involved) (and also to get bigger numbers :-) ) try sending the output to /dev/null instead of an actual file. (I.e. use of=/dev/null instead of of=/home/chris/tmp.dat) -- Erik Trulsson ertr1013@student.uu.se