From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161305AbWASTHY (ORCPT ); Thu, 19 Jan 2006 14:07:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161310AbWASTHX (ORCPT ); Thu, 19 Jan 2006 14:07:23 -0500 Received: from host233.omnispring.com ([69.44.168.233]:30931 "EHLO iradimed.com") by vger.kernel.org with ESMTP id S1161305AbWASTHV (ORCPT ); Thu, 19 Jan 2006 14:07:21 -0500 Message-ID: <43CFE34F.8060309@cfl.rr.com> Date: Thu, 19 Jan 2006 14:06:55 -0500 From: Phillip Susi User-Agent: Thunderbird 1.5 (Windows/20051201) MIME-Version: 1.0 To: Martin Drab CC: govind raj , linux-kernel@vger.kernel.org Subject: Re: RAID 5+0 support References: <43CFCBB2.3050003@cfl.rr.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 19 Jan 2006 19:08:10.0349 (UTC) FILETIME=[B031C9D0:01C61D2B] X-TM-AS-Product-Ver: SMEX-7.2.0.1122-3.51.1032-14215.000 X-TM-AS-Result: No--0.900000-5.000000-31 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Martin Drab wrote: > Speed is the issue here, I believe. By stripping two RAID-5 arrays you > ought to get the reliability of the RAID-5 but with considerably higher > speed. That's basically why RAID-50 exists, I think. One big raid-5 would have higher speed because it would have one more disk allocated to storing data rather than more parity. The raid 5+0 isn't really going to be any more reliable because it can withstand a single failure in either half, but not two failures in one half, so in the face of a double failure, you have a 50/50 chance of one being in each half.