From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f169.google.com ([209.85.216.169]:40991 "EHLO mail-qc0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756474AbaKRPn1 (ORCPT ); Tue, 18 Nov 2014 10:43:27 -0500 Received: by mail-qc0-f169.google.com with SMTP id w7so4743773qcr.0 for ; Tue, 18 Nov 2014 07:43:26 -0800 (PST) Message-ID: <546B68F8.6080008@ubuntu.com> Date: Tue, 18 Nov 2014 10:42:48 -0500 From: Phillip Susi MIME-Version: 1.0 To: Chris Murphy CC: Btrfs BTRFS Subject: Re: BTRFS messes up snapshot LV with origin References: <54699CC7.1050909@swiftspirit.co.za> <546A46A5.8030603@inwind.it> <27BDAC3B-789C-4477-B065-E703CE425F54@colorremedies.com> In-Reply-To: <27BDAC3B-789C-4477-B065-E703CE425F54@colorremedies.com> Content-Type: text/plain; charset=windows-1252 Sender: linux-btrfs-owner@vger.kernel.org List-ID: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 11/18/2014 1:16 AM, Chris Murphy wrote: > If fstab specifies rootfs as UUID, and there are two volumes with > the same UUID, it’s now ambiguous which one at boot time is the > intended rootfs. It’s no different than the days of /dev/sdXY where > X would change designations between boots = ambiguity and why we > went to UUID. He already said he has NOT rebooted, so there is no way that the snapshot has actually been mounted, even if it were UUID confusion. > So we kinda need a way to distinguish derivative volumes. Maybe > XFS and ext4 could easily change the volume UUID, but my vague > recollection is this is difficult on Btrfs? So that led me to the > idea of a way to create an on-the-fly (but consistent) “virtual > volume UUID” maybe based on a hash of both the LVM LV and fs > volume UUID. When using LVM, you should be referring to the volume by the LVM name rather than UUID. LVM names are stable, and don't have the duplicate uuid problem. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (MingW32) iQEcBAEBAgAGBQJUa2j4AAoJEI5FoCIzSKrwvywH/3yS25MAIwsGfIwBfCrNN5Qo NlBttcUcrYgOD/nQHEuulHdilWrvz3q6jGwVL9W8MQsHm0Ah5dMatT5e5zr1DSNC ZqSEXSE8jsYJu99FUWevxO7wtb94ioKa+OF1u0zsaA5yQUdaj5smPqK3iUfskUhs jE/vsJmws5iBv0dxnZI/6n3YqOB1Qck4PcMItRj8xvZQ0GjARIVw36pgJnmboGfY vWRmUXnTeLMu9ilHWhqNUIh3lTTUvRdaYoZtTr6eYh9sIntDCegN71WGmO8FfdjP vXhikg7Yx7FhkhxAl1X2NzM93d7fUSQDeQfTLYLMDbbTV/n2HwcoZ6G2+IQEJnQ= =3Lv1 -----END PGP SIGNATURE-----