From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751000AbWCBQsf (ORCPT ); Thu, 2 Mar 2006 11:48:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751294AbWCBQsf (ORCPT ); Thu, 2 Mar 2006 11:48:35 -0500 Received: from smtp.bulldogdsl.com ([212.158.248.7]:32785 "EHLO mcr-smtp-001.bulldogdsl.com") by vger.kernel.org with ESMTP id S1751000AbWCBQse (ORCPT ); Thu, 2 Mar 2006 11:48:34 -0500 X-Spam-Abuse: Please report all spam/abuse matters to abuse@bulldogdsl.com From: Alistair John Strachan To: Neil Brown Subject: RAID5 initial rebuild slow, 2.6.16-rc4 Date: Thu, 2 Mar 2006 16:48:21 +0000 User-Agent: KMail/1.9.1 Cc: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200603021648.21465.s0348365@sms.ed.ac.uk> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Neil, I recently purchased two SATA2 Western Digital WD2500KS (250GB) HDs to add to a pair of Maxtor DiamondMax 10's (200GB). I planned to initialise two 100GB RAID5 arrays spanning all four drives (the remaining 2x50GB on the new HDs is currently used for booting). All the drives are connected to the same controller. I'm running mdadm 2.3.1, which is the latest version I believe. I created the array with the following command: mdadm --create /dev/md1 --auto=yes --chunk=64 --level=5 --raid-devices=4 /dev/sda3 /dev/sdb3 /dev/sdc2 /dev/sdd2 A few seconds later the array completed and I got the following in /proc/mdstat: [root] 16:45 [~] cat /proc/mdstat Personalities : [raid0] [raid5] [raid4] [multipath] md2 : active raid0 sdb1[1] sda1[0] 195318016 blocks 32k chunks md1 : active raid5 sdd2[4] sdc2[2] sdb3[1] sda3[0] 298736448 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_] [>....................] recovery = 0.5% (501376/99578816) finish=1646.2min speed=1000K/sec I've not yet attempted to put a filesystem on the device, because I planned to wait until the (presumably pointless) recovery process completed. However, this rebuild seems to be extremely slow (the speed never exceeds the "minimum" recovery speed). CPU usage is almost nill. This machine is an Athlon64 X2 3800+, with 2GB RAM, running an x86_64 kernel. Is there any reason for this poor performance? -- Cheers, Alistair. 'No sense being pessimistic, it probably wouldn't work anyway.' Third year Computer Science undergraduate. 1F2 55 South Clerk Street, Edinburgh, UK.