From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932486AbWGASJc (ORCPT ); Sat, 1 Jul 2006 14:09:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933073AbWGASJc (ORCPT ); Sat, 1 Jul 2006 14:09:32 -0400 Received: from smtp1.ist.utl.pt ([193.136.128.21]:23748 "EHLO smtp1.ist.utl.pt") by vger.kernel.org with ESMTP id S932486AbWGASJb convert rfc822-to-8bit (ORCPT ); Sat, 1 Jul 2006 14:09:31 -0400 From: Claudio Martins To: Thomas Glanzmann Subject: Re: ext4 features Date: Sat, 1 Jul 2006 19:09:28 +0100 User-Agent: KMail/1.9.1 Cc: "Theodore Ts'o" , LKML References: <20060701163301.GB24570@cip.informatik.uni-erlangen.de> <20060701170729.GB8763@irc.pl> <20060701174716.GC24570@cip.informatik.uni-erlangen.de> In-Reply-To: <20060701174716.GC24570@cip.informatik.uni-erlangen.de> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200607011909.28685.ctpm@ist.utl.pt> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Saturday 01 July 2006 18:47, Thomas Glanzmann wrote: > Hello, > > > Checksums are not very useful for themselves. They are useful when we > > have other copy of data (think raid mirroring) so data can be > > reconstructed from working copy. > > it would be possible to identify data corruption. > > > What's wrong with DM snapshots? > > they're inefficient in matter of disk space consumption because they > don't have a clue of the filesystems that are on top of them. > May I recommend that you have a look at NILFS? http://nilfs.org/en/ The design is built from the ground up to support an almost arbitrary number of snapshots, and also has other advantages. And it works already. Regards Cláudio