From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:36472) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T5Zat-0007KY-FD for qemu-devel@nongnu.org; Sun, 26 Aug 2012 05:57:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T5Zar-0006Nl-3N for qemu-devel@nongnu.org; Sun, 26 Aug 2012 05:57:23 -0400 Received: from mailpro.odiso.net ([89.248.209.98]:39686) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T5Zaq-0006Na-R0 for qemu-devel@nongnu.org; Sun, 26 Aug 2012 05:57:21 -0400 Date: Sun, 26 Aug 2012 11:56:54 +0200 (CEST) From: Alexandre DERUMIER Message-ID: <835dcf7c-af96-4196-9be7-84755f06ccf0@mailpro> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [Qemu-devel] qcow2: online snasphots : internal vs external ? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Jeff Cody , qemu-devel >>Using snapshot capabilities of the underlying storage is a good idea. >>LVM snapshots have been used with KVM for a long time. The same works >>for zfs, btrfs, etc. They are probably more efficient than using >>QEMU's external snapshots, which must copy data between image files >>when flattening the image chain. Yes, indeed ;) But I'll try to add feature to proxmox for all kind of stor= age. >>It should work if you shut down the guest before manipulating snapshots. = Oh, sorry, I have redone test with stopping the vm before manipulate, and i= t's work fine now. It is possible to achieve the same behaviour with external snapshot ? (I wo= uld like to do it online) I don't see how I can rollback to the point of time of the snapshot. Also I see that snapshot_blkdev qmp command give in his description: "Otherwise the snapshot will be internal! (currently unsupported)." is Live internal snapshots on the roadmap ? Thanks Again, Alexandre Derumier ----- Mail original ----- De: "Stefan Hajnoczi" =C3=80: "Alexandre DERUMIER" Cc: "Jeff Cody" , "qemu-devel" Envoy=C3=A9: Dimanche 26 Ao=C3=BBt 2012 09:07:44 Objet: Re: [Qemu-devel] qcow2: online snasphots : internal vs external ? On Sat, Aug 25, 2012 at 6:06 PM, Alexandre DERUMIER w= rote: > I work since many years with snapshot on zfs or netapp, > and on these system like ceph, I can rollback at the time of the snapshot= , and have a view of when the snapshot was taken. > > exemple : > image1 : empty dir / > take a snapshot (snap1) > touch /file1 > now rollback to snap1 > ls / ->empty dir, like when snap1 was taken Using snapshot capabilities of the underlying storage is a good idea. LVM snapshots have been used with KVM for a long time. The same works for zfs, btrfs, etc. They are probably more efficient than using QEMU's external snapshots, which must copy data between image files when flattening the image chain. > now,example with qemu: > image1 : empty dir / Did you shut down the guest here? > take a snapshot: (qemu-img snapshot -c snap1 image1) > touch /file1 Did you shut down the guest here? > now rollback to snap1 (qemu-img snapshot -a snap1 image1) > ls /file1 > > > the behaviour is completly different. Did I miss something ? It should work if you shut down the guest before manipulating snapshots. Stefan -- -- Alexandre D e rumier Ing=C3=A9nieur Syst=C3=A8mes et R=C3=A9seaux Fixe : 03 20 68 88 85 Fax : 03 20 68 90 88 45 Bvd du G=C3=A9n=C3=A9ral Leclerc 59100 Roubaix 12 rue Marivaux 75002 Paris