From owner-freebsd-stable@FreeBSD.ORG Tue Jun 21 14:51:14 2005 Return-Path: X-Original-To: freebsd-stable@FreeBSD.ORG Delivered-To: freebsd-stable@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2C60A16A41C for ; Tue, 21 Jun 2005 14:51:14 +0000 (GMT) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (lurza.secnetix.de [83.120.8.8]) by mx1.FreeBSD.org (Postfix) with ESMTP id 82EFB43D1F for ; Tue, 21 Jun 2005 14:51:13 +0000 (GMT) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (stojuz@localhost [127.0.0.1]) by lurza.secnetix.de (8.13.1/8.13.1) with ESMTP id j5LEpAWn024351; Tue, 21 Jun 2005 16:51:10 +0200 (CEST) (envelope-from oliver.fromme@secnetix.de) Received: (from olli@localhost) by lurza.secnetix.de (8.13.1/8.13.1/Submit) id j5LEpA2W024350; Tue, 21 Jun 2005 16:51:10 +0200 (CEST) (envelope-from olli) Date: Tue, 21 Jun 2005 16:51:10 +0200 (CEST) Message-Id: <200506211451.j5LEpA2W024350@lurza.secnetix.de> From: Oliver Fromme To: freebsd-stable@FreeBSD.ORG, Michael Schuh In-Reply-To: <1dbad315050621051525f4c6fc@mail.gmail.com> X-Newsgroups: list.freebsd-stable User-Agent: tin/1.5.4-20000523 ("1959") (UNIX) (FreeBSD/4.11-RELEASE (i386)) MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Cc: Subject: Re: FreeBSD MySQL still WAY slower than Linux X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-stable@FreeBSD.ORG, Michael Schuh List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Jun 2005 14:51:14 -0000 Michael Schuh wrote: > As i sayed i have the installations always made in the same way, so that i mean. > I mean i have alwas made the swap on the first gig of the disk, and > the installation > on the rest of the disk. and i have no multiple os'es on these disk. The problem is that the file (from "dd of=foo") can still end up at completely different physical places on the disk. It depends on the filesystem (ext2, ext3, UFS, whatever) and on the allocation strategies of the filesystem code. UFS might start filling cylinder groups from the beginning of the disk, while ext3 might start at the end (does ext3 even _have_ cylinder groups?). This was just an example, but you get the idea. Of course, it also depends on how much data there already is on the filesystem, and how it is distributed over the disk. For accurate measurements and comparisons, you have to make sure to use _exactly_ the same physical location on the disk. From userland you don't have a way to control the physical allocation of files. Therefore, the only reliable way is to leave an unused partition on the disk, do _not_ put a filesystem on it, and use the raw device in the »dd« command. If you do this, you will always hit the same physical location on the disk. But then again -- as others have already mentioned, serial write speed is not the most important factor for database performance (although the WAL journal files of advanced transactional databases like PostgreSQL are written in a sequential way), so the usefulness of this "benchmark" is very debatable. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co KG, Oettingenstr. 2, 80538 München Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "I started using PostgreSQL around a month ago, and the feeling is similar to the switch from Linux to FreeBSD in '96 -- 'wow!'." -- Oddbjorn Steffensen