Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760926AbYCYWAe (ORCPT ); Tue, 25 Mar 2008 18:00:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754007AbYCYWA0 (ORCPT ); Tue, 25 Mar 2008 18:00:26 -0400 Received: from mx1.redhat.com ([66.187.233.31]:40915 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753473AbYCYWAZ (ORCPT ); Tue, 25 Mar 2008 18:00:25 -0400 Message-ID: <47E975F8.3000702@redhat.com> Date: Tue, 25 Mar 2008 18:00:24 -0400 From: Chris Snook User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: Emmanuel Florac CC: linux-kernel@vger.kernel.org Subject: Re: RAID-1 performance under 2.4 and 2.6 References: <20080325194306.4ac71ff2@galadriel.home> In-Reply-To: <20080325194306.4ac71ff2@galadriel.home> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1544 Lines: 34 Emmanuel Florac wrote: > I post there because I couldn't find any information about this > elsewhere : on the same hardware ( Athlon X2 3500+, 512MB RAM, 2x400 GB > Hitachi SATA2 hard drives ) the 2.4 Linux software RAID-1 (tested 2.4.32 > and 2.4.36.2, slightly patched to recognize the hardware :p) is way > faster than 2.6 ( tested 2.6.17.13, 2.6.18.8, 2.6.22.16, 2.6.24.3) > especially for writes. I actually made the test on several different > machines (same hard drives though) and it remained consistent across > the board, with /mountpoint a software RAID-1. > Actually checking disk activity with iostat or vmstat shows clearly a > cache effect much more pronounced on 2.4 (i.e. writing goes on much > longer in the background) but it doesn't really account for the > difference. I've also tested it thru NFS from another machine (Giga > ethernet network): > > dd if=/dev/zero of=/mountpoint/testfile bs=1M count=1024 > > kernel 2.4 2.6 2.4 thru NFS 2.6 thru NFS > > write 90 MB/s 65 MB/s 70 MB/s 45 MB/s > read 90 MB/s 80 MB/s 75 MB/s 65 MB/s > > Duh. That's terrible. Does it mean I should stick to (heavily > patched...) 2.4 for my file servers or... ? :) > It means you shouldn't use dd as a benchmark. -- Chris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/