From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265238AbUEYXrN (ORCPT ); Tue, 25 May 2004 19:47:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265243AbUEYXrN (ORCPT ); Tue, 25 May 2004 19:47:13 -0400 Received: from skif.spylog.com ([194.67.35.250]:42184 "EHLO mail.spylog.com") by vger.kernel.org with ESMTP id S265238AbUEYXrK (ORCPT ); Tue, 25 May 2004 19:47:10 -0400 Date: Wed, 26 May 2004 03:46:57 +0400 From: Andrey Nekrasov Reply-To: Andrey Nekrasov X-Priority: 3 (Normal) Message-ID: <1236867749.20040526034657@spylog.ru> To: linux-kernel@vger.kernel.org Subject: sata promise and software raid5... MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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 --