From owner-freebsd-questions@FreeBSD.ORG Mon Aug 21 17:25:15 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org 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 C3B8F16A4DA for ; Mon, 21 Aug 2006 17:25:15 +0000 (UTC) (envelope-from bsdml@werner.st) Received: from mail.werner.st (mail.werner.st [85.126.91.53]) by mx1.FreeBSD.org (Postfix) with ESMTP id D3FCC43D7C for ; Mon, 21 Aug 2006 17:25:08 +0000 (GMT) (envelope-from bsdml@werner.st) Received: from localhost (localhost.local.werner.st [127.0.0.1]) by mail.werner.st (Postfix) with ESMTP id 8C15F5C89; Mon, 21 Aug 2006 19:25:12 +0200 (CEST) Received: from mail.werner.st ([127.0.0.1]) by localhost (web01.local.werner.st [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 04084-03; Mon, 21 Aug 2006 19:25:10 +0200 (CEST) Received: by mail.werner.st (Postfix, from userid 1012) id C634B5C91; Mon, 21 Aug 2006 19:25:07 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.1.4 (2006-07-25) on web01.local.werner.st X-Spam-Level: X-Spam-Status: No, score=-0.9 required=4.0 tests=ALL_TRUSTED,NO_REAL_NAME, SPF_HELO_PASS autolearn=disabled version=3.1.4 Received: from webmail.werner.st (localhost.local.werner.st [127.0.0.1]) by mail.werner.st (Postfix) with ESMTP id AE0B45C89; Mon, 21 Aug 2006 19:25:05 +0200 (CEST) Received: from 85.126.91.51 (SquirrelMail authenticated user bsdml) by webmail.werner.st with HTTP; Mon, 21 Aug 2006 19:25:05 +0200 (CEST) Message-ID: <15985.85.126.91.51.1156181105.squirrel@webmail.werner.st> In-Reply-To: <003701c6c540$d0744f20$0a01a8c0@superman> References: <000701c6c539$bbb33710$0a01a8c0@superman> <20060821162156.GB45306@dan.emsphone.com> <003701c6c540$d0744f20$0a01a8c0@superman> Date: Mon, 21 Aug 2006 19:25:05 +0200 (CEST) From: bsdml@werner.st To: "Chris Knipe" User-Agent: SquirrelMail/1.4.5 MIME-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal X-Virus-Scanned: amavisd-new at werner.st Cc: Dan Nelson , freebsd-questions@freebsd.org Subject: Re: sluggish disk performance. X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 21 Aug 2006 17:25:15 -0000 Hi >> In the last episode (Aug 21), Chris Knipe said: >>> Disks ad0 ofod intrn >>> KB/t 16.83 %slo-z 35456 buf >>> tps 103 4 tfree 414 dirtybuf well, with 100% random I/O at 7200rpm (or 120rpm per second = maximum number of theoretical IOPS) that is a typical number I see everywhere. The 16KB average I/O-Size are OK but could be higher - but definitely your I/O-Pattern an not the avg. transactions size are the cause of your 1.7MB/sec >>> MB/s 1.70 20988 desiredvnodes >>> % busy 98 5247 numvnodes >>> 4223 freevnodes >>> >>> Got 1 ATA100 Seagate 120GB disk in there at the moment.... 1.7MB/s at >>> 98% busy? Surely, that figure is WAY low??? I'd expect atleast >>> about 10MB/s on ATA100. >> >> That number's about right for random I/O and small blocksizes, which is >> what the KB/t field shows. If you were doing sequential I/O, the KB/t >> field would be at or near 128. Are you also running a "du", "cvs >> update", or other command likely to be doing random disk accesses? > > ALTER TABLE on a 200MB mySQL table? > > I guess its time for a dedicated disk then.... Depends on the number of random I/O's you want to be able to handle - could be that you might want 2 or more aswell :-) Cheers, Martin