From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261155AbVGYMcZ (ORCPT ); Mon, 25 Jul 2005 08:32:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261156AbVGYMcZ (ORCPT ); Mon, 25 Jul 2005 08:32:25 -0400 Received: from thunk.org ([69.25.196.29]:47042 "EHLO thunker.thunk.org") by vger.kernel.org with ESMTP id S261155AbVGYMcX (ORCPT ); Mon, 25 Jul 2005 08:32:23 -0400 Date: Mon, 25 Jul 2005 08:32:04 -0400 From: "Theodore Ts'o" To: "Amit S. Kale" Cc: Jan Engelhardt , Pavel Machek , Linux Kernel Subject: Re: CheckFS: Checkpoints and Block Level Incremental Backup (BLIB) Message-ID: <20050725123204.GB7925@thunk.org> Mail-Followup-To: Theodore Ts'o , "Amit S. Kale" , Jan Engelhardt , Pavel Machek , Linux Kernel References: <200507231130.07208.amitkale@linsyssoft.com> <20050724142352.GB1778@elf.ucw.cz> <200507251124.43898.amitkale@linsyssoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200507251124.43898.amitkale@linsyssoft.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 25, 2005 at 11:24:43AM +0530, Amit S. Kale wrote: > On Sunday 24 Jul 2005 8:44 pm, Jan Engelhardt wrote: > > >Maybe you want to put your development machines on ext*2* while doing > > >this ;-). Or perhaps reiserfs/xfs/something. > > > > Or perhaps into at the VFS level, so any fs can benefit from it. > > We thought about that. While it's possible to do that, it would need > hooks into all filesystems etc. Definitely worth trying once we get > some more basic stuff working for ext3 > > After all the things that need to be saved at the time of taking a > checkpoint for any filesystem would be the superblock and inode > table (or their equivalents). Everything else is automatically taken > care of. You are aware of the block-device-level snapshot solutions, right? They can be more painful to use, although that's mostly a UI issue, and they have the added advantage that you can safely run e2fsck on the snapshot image if you want to check the consistency of the filesystem while it is mounted. (If it is clean, you can then use tune2fs to reset the max-mount-count and last-checked-time on the original filesystem image; if it is not clean, you can send e-mail to the system administrator suggesting that she schedule downtime ASAP and do a e2fsck on the filesystem image. This is a good thing that a paranoid sysadmin might schedule via cron every Saturday morning at 3am, for example.) - Ted