Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1767520AbXECQyl (ORCPT ); Thu, 3 May 2007 12:54:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1767515AbXECQyl (ORCPT ); Thu, 3 May 2007 12:54:41 -0400 Received: from smtpout.mac.com ([17.250.248.175]:57616 "EHLO smtpout.mac.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1767520AbXECQyk (ORCPT ); Thu, 3 May 2007 12:54:40 -0400 In-Reply-To: <20070503151047.GB3866@ucw.cz> References: <1177567481.5025.211.camel@nigel.suspend2.net> <1177654110.4737.91.camel@nigel.suspend2.net> <200704272324.43359.rjw@sisk.pl> <1177711666.4737.176.camel@nigel.suspend2.net> <35EFC5BA-D16B-41BE-A641-AEA8CCC9E0BE@mac.com> <20070503151047.GB3866@ucw.cz> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: Cc: nigel@nigel.suspend2.net, Linus Torvalds , "Rafael J. Wysocki" , Pekka J Enberg , LKML Content-Transfer-Encoding: 7bit From: Kyle Moffett Subject: Re: Back to the future. Date: Thu, 3 May 2007 12:53:48 -0400 To: Pavel Machek X-Mailer: Apple Mail (2.752.2) X-Brightmail-Tracker: AAAAAA== X-Brightmail-scanned: yes Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1544 Lines: 33 On May 03, 2007, at 11:10:47, Pavel Machek wrote: > How mature is freezing filesystems -- will it work on at least > ext2/3 and vfat? I'm pretty sure it works on ext2/3 and xfs and possibly others, I don't know either way about VFAT though. Essentially the "freeze" part involves telling the filesystem to sync all data, flush the journal, and mark the filesystem clean. The intent under dm/LVM was to allow you to make snapshots without having to fsck the just- created snapshot before you mounted it. > What happens if you try to boot and filesystems are frozen from > previous run? If you're just doing a fresh boot then the filesystem is already clean due to the dm freeze and so it mounts up normally. All you need to do then is have a little startup script which purges the saved image before you fsck or remount things read-write since either case means the image is no longer safe to resume. If the kernel is later modified to purge all filesystem data (dcache/ pagecache) during snapshot and effectively remount and reopen all the files by path during restore then you could remove that requirement. You'd just need to make sure that the restore-from-disk scripts did an fsck or journal-restore before reloading the old kernel data. Cheers, Kyle Moffett - 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/