From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264508AbTLQShv (ORCPT ); Wed, 17 Dec 2003 13:37:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264511AbTLQShv (ORCPT ); Wed, 17 Dec 2003 13:37:51 -0500 Received: from mta7.pltn13.pbi.net ([64.164.98.8]:15536 "EHLO mta7.pltn13.pbi.net") by vger.kernel.org with ESMTP id S264508AbTLQShu (ORCPT ); Wed, 17 Dec 2003 13:37:50 -0500 Date: Wed, 17 Dec 2003 10:37:39 -0800 From: Mike Fedyk To: Linus Torvalds Cc: Peter Zaitsev , Helge Hafting , jw schultz , Linux Kernel Mailing List Subject: Re: raid0 slower than devices it is assembled of? Message-ID: <20031217183739.GG1402@matchmail.com> Mail-Followup-To: Linus Torvalds , Peter Zaitsev , Helge Hafting , jw schultz , Linux Kernel Mailing List References: <200312151434.54886.adasi@kernel.pl> <20031216040156.GJ12726@pegasys.ws> <3FDF1C03.2020509@aitel.hist.no> <20031216205853.GC1402@matchmail.com> <1071657159.2155.76.camel@abyss.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 17, 2003 at 08:01:13AM -0800, Linus Torvalds wrote: > However, since seeking will be limited by the checksum drive anyway (for > writing), the advantages of large stripes in trying to keep the disks > independent aren't as one-sided. It seems to me that you are referring to a single pairity drive in the array. That is raid4, where only one drive handles the pairity data for the entire array regardless of array size. Raid5 staggers the pairidy data (md has four different staggering layouts) so that the data, and pairity are on two different drives, and that varies based on stripe and layout.