Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161414AbWASUQA (ORCPT ); Thu, 19 Jan 2006 15:16:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161409AbWASUP7 (ORCPT ); Thu, 19 Jan 2006 15:15:59 -0500 Received: from kepler.fjfi.cvut.cz ([147.32.6.11]:38028 "EHLO kepler.fjfi.cvut.cz") by vger.kernel.org with ESMTP id S1161411AbWASUP6 (ORCPT ); Thu, 19 Jan 2006 15:15:58 -0500 Date: Thu, 19 Jan 2006 21:14:28 +0100 (CET) From: Martin Drab To: Phillip Susi cc: govind raj , linux-kernel@vger.kernel.org Subject: Re: RAID 5+0 support In-Reply-To: <43CFE34F.8060309@cfl.rr.com> Message-ID: References: <43CFCBB2.3050003@cfl.rr.com> <43CFE34F.8060309@cfl.rr.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 996 Lines: 23 On Thu, 19 Jan 2006, Phillip Susi wrote: > 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. Well, yes and no. See for instance: http://en.wikipedia.org/wiki/RAID#RAID_50_.28RAID_5.2B0.29 Martin - 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/