From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261586AbTJRLvr (ORCPT ); Sat, 18 Oct 2003 07:51:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261585AbTJRLuz (ORCPT ); Sat, 18 Oct 2003 07:50:55 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:2534 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S261582AbTJRLuu (ORCPT ); Sat, 18 Oct 2003 07:50:50 -0400 Date: Sat, 18 Oct 2003 12:50:49 +0100 From: "Dr. David Alan Gilbert" To: linux-kernel@vger.kernel.org Subject: Re: Software RAID5 with 2.6.0-test Message-ID: <20031018115049.GB760@gallifrey> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Chocolate: 70 percent or better cocoa solids preferably X-Operating-System: Linux/2.6.0-test6 (i686) X-Uptime: 12:46:23 up 1:48, 1 user, load average: 0.37, 0.40, 0.43 User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, First off, I am never going to try building a software IDE RAID 5 on Linux again in an important production system - my experience says that it just isn't possible to get that many IDE channels to work together reliably. I know there are some people who have managed it, and I did hear there was a race condition and a patch to fix it - but in the end in a production system with a serious size of RAID throwing in a 3-ware or similar is a hell of a lot simpler and just works. As for speed; well I'm not sure. I think the comparisons of 100MHz processors vs the speed of your xeon are bogus. I would hope at least some of the work on the hardware raid controllers is done in hardware (XORing blocks of data isn't exactly hard in hardware), and in addition the amount of CPU used is going to be limited by memory bandwidth (and associated cache pollution?) before the clock rate of the processor gets involved I would have thought. I'd love to see some real benchmarks to prove me wrong however! Dave -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux on Alpha,68K| Happy \ \ gro.gilbert @ treblig.org | MIPS,x86,ARM,SPARC,PPC & HPPA | In Hex / \ _________________________|_____ http://www.treblig.org |_______/