Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965314AbWLPBUO (ORCPT ); Fri, 15 Dec 2006 20:20:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965319AbWLPBUN (ORCPT ); Fri, 15 Dec 2006 20:20:13 -0500 Received: from sbcs.cs.sunysb.edu ([130.245.1.15]:37261 "EHLO sbcs.cs.sunysb.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965314AbWLPBUJ (ORCPT ); Fri, 15 Dec 2006 20:20:09 -0500 Date: Fri, 15 Dec 2006 20:20:02 -0500 (EST) From: Nikolai Joukov X-X-Sender: kolya@compserv1 To: Bryan Henderson cc: Ed Tomlinson , linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [ANNOUNCE] RAIF: Redundant Array of Independent Filesystems In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1581 Lines: 38 > >The idea behind the cloneset is that most of the blocks (or files) > >do not change in either source or target. This being the case its only > necessary > >to update the changed elements. This means updates are incremental. Once > >the system has figured out what it needs to update its usable and if you > access > >an element that should be updated you will see the correctly updated > version - even > >though backgound resyncing is still in progress. > > I still can't tell what you're describing. With RAID1 as well, only > changed elements ever get updated. I have two identical filesystems, > members of a RAIF set. I change one file. One file in each member > filesystem gets updated, and I again have two identical filesystems. > > How would a cloneset work differently, and how would it be better? Thanks, Bryan. I was about to write almost the same. > > This type of logic is great for backups. > > Can you give an example of using it for backup? I guess, you can mount Versionfs (yet another stackable file system) below RAIF and above one of the lower file systems or use some other versioning file system such as ext3cow. This will allow rolling back to any older file system version at any time. Nikolai. --------------------- Nikolai Joukov, Ph.D. Filesystems and Storage Laboratory Stony Brook University - 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/