From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267183AbUBMTac (ORCPT ); Fri, 13 Feb 2004 14:30:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264353AbUBMTac (ORCPT ); Fri, 13 Feb 2004 14:30:32 -0500 Received: from 80-169-17-66.mesanetworks.net ([66.17.169.80]:56736 "EHLO mail.bounceswoosh.org") by vger.kernel.org with ESMTP id S267183AbUBMTa1 (ORCPT ); Fri, 13 Feb 2004 14:30:27 -0500 Date: Fri, 13 Feb 2004 12:30:46 -0700 From: "Eric D. Mudama" To: Willy Tarreau Cc: Timothy Miller , Linux Kernel Mailing List Subject: Re: File system performance, hardware performance, ext3, 3ware RAID1, etc. Message-ID: <20040213193046.GA17790@bounceswoosh.org> Mail-Followup-To: Willy Tarreau , Timothy Miller , Linux Kernel Mailing List References: <402C0D0F.6090203@techsource.com> <20040213055350.GG29363@alpha.home.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20040213055350.GG29363@alpha.home.local> User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 13 at 6:53, Willy Tarreau wrote: >It depends on the disk too. Lots of disks (specially IDE) are far slower >on writes than they are on reads. This may be a function of the operating system or the filesystem, but it isn't necessarilly an artifact of the drives themselves. With both read and write caching enabled, random writes will always be faster than random reads from the drive perspective. Even with queueing enabled (legacy TCQ or Native-SATA "NCQ"), your ability to reorder reads is limited in ATA to 32 tags, while the ability to reorder cached writes is limited only by buffer size and cache granularity... the absolute worst-case write performance should be the same as read performance. --eric -- Eric D. Mudama edmudama@mail.bounceswoosh.org