From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758787AbXFRE6x (ORCPT ); Mon, 18 Jun 2007 00:58:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758207AbXFRE6X (ORCPT ); Mon, 18 Jun 2007 00:58:23 -0400 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:47235 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755947AbXFRE6V (ORCPT ); Mon, 18 Jun 2007 00:58:21 -0400 Date: Mon, 18 Jun 2007 14:57:59 +1000 From: David Chinner To: Neil Brown Cc: Avi Kivity , david@lang.hm, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org Subject: Re: limits on raid Message-ID: <20070618045759.GD85884050@sgi.com> References: <18034.479.256870.600360@notabene.brown> <18034.3676.477575.490448@notabene.brown> <467273AB.9010202@argo.co.il> <18035.3009.568832.785308@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <18035.3009.568832.785308@notabene.brown> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 16, 2007 at 07:59:29AM +1000, Neil Brown wrote: > Combining these thoughts, it would make a lot of sense for the > filesystem to be able to say to the block device "That blocks looks > wrong - can you find me another copy to try?". That is an example of > the sort of closer integration between filesystem and RAID that would > make sense. I think that this would only be useful on devices that store discrete copies of the blocks on different devices i.e. mirrors. If it's an XOR based RAID, you don't have another copy you can retreive.... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group