Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754400Ab3CTK3r (ORCPT ); Wed, 20 Mar 2013 06:29:47 -0400 Received: from mondschein.lichtvoll.de ([194.150.191.11]:55356 "EHLO mail.lichtvoll.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750835Ab3CTK3p convert rfc822-to-8bit (ORCPT ); Wed, 20 Mar 2013 06:29:45 -0400 From: Martin Steigerwald To: David Lang Subject: Re: Tux3 Report: Initial fsck has landed Date: Wed, 20 Mar 2013 11:29:41 +0100 User-Agent: KMail/1.13.7 (Linux/3.9.0-rc3-tp520; KDE/4.9.5; x86_64; ; ) Cc: tux3@phunq.net, Daniel Phillips , "Theodore Ts'o" , "Darrick J. Wong" , linux-kernel@vger.kernel.org, tux3@tux3.org, linux-fsdevel@vger.kernel.org References: <201303200000.33356.Martin@lichtvoll.de> (sfid-20130320_112832_061423_065C04E5) In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Message-Id: <201303201129.41996.Martin@lichtvoll.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2116 Lines: 45 Am Mittwoch, 20. M?rz 2013 schrieb David Lang: > On Wed, 20 Mar 2013, Martin Steigerwald wrote: > > Am Dienstag, 29. Januar 2013 schrieb Daniel Phillips: > >> On Mon, Jan 28, 2013 at 5:40 PM, Theodore Ts'o wrote: > >>> On Mon, Jan 28, 2013 at 04:20:11PM -0800, Darrick J. Wong wrote: > >>>> On Mon, Jan 28, 2013 at 03:27:38PM -0800, David Lang wrote: > >>>>> The situation I'm thinking of is when dealing with VMs, you make a > >>>>> filesystem image once and clone it multiple times. Won't that end > >>>>> up with the same UUID in the superblock? > >>>> > >>>> Yes, but one ought to be able to change the UUID a la tune2fs > >>>> -U. Even still... so long as the VM images have a different UUID > >>>> than the fs that they live on, it ought to be fine. > >>> > >>> ... and this is something most system administrators should be > >>> familiar with. For example, it's one of those things that Norton > >>> Ghost when makes file system image copes (the equivalent of "tune2fs > >>> -U random /dev/XXX") > >> > >> Hmm, maybe I missed something but it does not seem like a good idea > >> to use the volume UID itself to generate unique-per-volume metadata > >> hashes, if users expect to be able to change it. All the metadata > >> hashes would need to be changed. > > > > I believe that is what BTRFS is doing. > > > > And yes, AFAIK there is no easy way to change the UUID of a BTRFS > > filesystems after it was created. > > In a world where systems are cloned, and many VMs are started from one > master copy of a filesystem, a UUID is about as far from unique as > anything you can generate. > > BTRFS may have this problem, but why should Tux3 copy the problem? I didn?t ask for copying that behavior. I just mentioned it :) -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 -- 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/