Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263865AbUCZAdX (ORCPT ); Thu, 25 Mar 2004 19:33:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263859AbUCZAcs (ORCPT ); Thu, 25 Mar 2004 19:32:48 -0500 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:21717 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S263856AbUCZAPM (ORCPT ); Thu, 25 Mar 2004 19:15:12 -0500 Message-ID: <40637603.10902@pobox.com> Date: Thu, 25 Mar 2004 19:14:59 -0500 From: Jeff Garzik User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030703 X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Justin T. Gibbs" CC: linux-kernel@vger.kernel.org, Kevin Corry , Neil Brown , linux-raid@vger.kernel.org Subject: Re: "Enhanced" MD code avaible for review References: <760890000.1079727553@aslan.btc.adaptec.com> <16480.61927.863086.637055@notabene.cse.unsw.edu.au> <40624235.30108@pobox.com> <200403251200.35199.kevcorry@us.ibm.com> <40632804.1020101@pobox.com> <40632994.7080504@pobox.com> <1035780000.1080258411@aslan.btc.adaptec.com> <406372C5.600@pobox.com> <1048370000.1080259823@aslan.btc.adaptec.com> In-Reply-To: <1048370000.1080259823@aslan.btc.adaptec.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1357 Lines: 35 Justin T. Gibbs wrote: >>>None of the solutions being talked about perform "failing over" in >>>userland. The RAID transforms which perform this operation are kernel >>>resident in DM, MD, and EMD. Perhaps you are talking about spare >>>activation and rebuild? >> >>This is precisely why I sent the second email, and made the qualification >>I did :) >> >>For a "do it in userland" solution, an initrd or initramfs piece examines >>the system configuration, and assembles physical disks into RAID arrays >>based on the information it finds. I was mainly implying that an initrd >>solution would have to provide some primitive failover initially, before >>the kernel is bootstrapped... much like a bootloader that supports booting >>off a RAID1 array would need to do. > > > "Failover" (i.e. redirecting a read to a viable member) will not occur > via userland at all. The initrd solution just has to present all available > members to the kernel interface performing the RAID transform. There > is no need for "special failover handling" during bootstrap in either > case. hmmm, yeah, agreed. Jeff - 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/