From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265310AbUEZEYf (ORCPT ); Wed, 26 May 2004 00:24:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265311AbUEZEYf (ORCPT ); Wed, 26 May 2004 00:24:35 -0400 Received: from willy.net1.nerim.net ([62.212.114.60]:39439 "EHLO willy.net1.nerim.net") by vger.kernel.org with ESMTP id S265310AbUEZEYP (ORCPT ); Wed, 26 May 2004 00:24:15 -0400 Date: Wed, 26 May 2004 06:21:44 +0200 From: Willy Tarreau To: Andrey Nekrasov Cc: linux-kernel@vger.kernel.org Subject: Re: sata promise and software raid5... Message-ID: <20040526042144.GE578@alpha.home.local> References: <1236867749.20040526034657@spylog.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1236867749.20040526034657@spylog.ru> User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, I think I had the same problem on a PIIX SATA with RAID1. Basically, I noticed that each disk could be accessed one at a time, and that it was totally impossible to access the second one while the first one was reading. A simple "cat /dev/sda >/dev/null" prevented anyone from logging into the box or doing anything which required disk I/O. So if you have the same problem, I can fairly understand your low numbers. Could you try something like : # cat /dev/sda >/dev/null & # hdparm -t /dev/sdb If hdparm doesn't start before the 'cat' ends, you do have the same problem. Well, I don't know where it comes from, and unfortunately I don't have the machine anymore to try fixes. Regards, Willy On Wed, May 26, 2004 at 03:46:57AM +0400, Andrey Nekrasov wrote: > Hello, > > controller - Promise SATA 150 TX4, linux 2.6.7-rc1-bk1, HDD Maxtor > 250Gb (x4) > > Why so slowly reads (and writes) with software raid5? > > gnome:~ # hdparm -t /dev/sda2 > > /dev/sda2: > Timing buffered disk reads: 148 MB in 3.01 seconds = 49.16 MB/sec > gnome:~ # hdparm -t /dev/sdb2 > > /dev/sdb2: > Timing buffered disk reads: 148 MB in 3.02 seconds = 49.01 MB/sec > gnome:~ # hdparm -t /dev/sdc2 > > /dev/sdc2: > Timing buffered disk reads: 148 MB in 3.03 seconds = 48.90 MB/sec > gnome:~ # hdparm -t /dev/sdd2 > > /dev/sdd2: > Timing buffered disk reads: 144 MB in 3.00 seconds = 47.96 MB/sec > gnome:~ # > gnome:~ # > gnome:~ # hdparm -t /dev/md0 > > /dev/md0: > Timing buffered disk reads: 64 MB in 3.12 seconds = 20.52 MB/sec > gnome:~ # > > > gnome:~ # cat /etc/raidtab > raiddev /dev/md0 > raid-level 5 > nr-raid-disks 4 > nr-spare-disks 0 > persistent-superblock 1 > parity-algorithm left-symmetric > chunk-size 1024 > > device /dev/sda2 > raid-disk 0 > > device /dev/sdb2 > raid-disk 1 > > device /dev/sdc2 > raid-disk 2 > > device /dev/sdd2 > raid-disk 3 > > > bye > -- > > > - > 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/