Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759377AbYCYSp5 (ORCPT ); Tue, 25 Mar 2008 14:45:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757670AbYCYSpj (ORCPT ); Tue, 25 Mar 2008 14:45:39 -0400 Received: from postfix2-g20.free.fr ([212.27.60.43]:56951 "EHLO postfix2-g20.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757484AbYCYSpi (ORCPT ); Tue, 25 Mar 2008 14:45:38 -0400 Date: Tue, 25 Mar 2008 19:43:06 +0100 From: Emmanuel Florac To: linux-kernel@vger.kernel.org Subject: RAID-1 performance under 2.4 and 2.6 Message-ID: <20080325194306.4ac71ff2@galadriel.home> Organization: Intellique X-Mailer: Claws Mail 2.9.1 (GTK+ 2.8.20; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1575 Lines: 34 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... ? :) -- -------------------------------------------------- Emmanuel Florac www.intellique.com -------------------------------------------------- -- 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/