From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752568AbYE1Qkk (ORCPT ); Wed, 28 May 2008 12:40:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751591AbYE1Qk3 (ORCPT ); Wed, 28 May 2008 12:40:29 -0400 Received: from mx1.redhat.com ([66.187.233.31]:42227 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751443AbYE1Qk2 (ORCPT ); Wed, 28 May 2008 12:40:28 -0400 Message-ID: <483D8AE0.8090606@redhat.com> Date: Wed, 28 May 2008 12:40:00 -0400 From: Chris Snook User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: =?ISO-8859-1?Q?Jens_B=E4ckman?= CC: Justin Piszcz , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, xfs@oss.sgi.com Subject: Re: Performance Characteristics of All Linux RAIDs (mdadm/bonnie++) References: <95711f160805280934y77ed7d91tec5aeb531bf8013c@mail.gmail.com> In-Reply-To: <95711f160805280934y77ed7d91tec5aeb531bf8013c@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jens Bäckman wrote: > On Wed, May 28, 2008 at 10:53 AM, Justin Piszcz wrote: >> Results: >> >> http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.html >> http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.txt > > Either the RAID 1 read speed must be wrong, or something is odd in the > Linux implementation. There's six drives that can be used for reading > at the same time, as they contain the very same data. 63MB/s > sequential looks like what you would get from a single drive. The test is a single thread reading one block at a time, so this is not surprising. If you get this doing multi-megabyte readahead, or with several threads, something is very wrong. -- Chris