From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39854) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xr6ej-0000Jr-Lp for qemu-devel@nongnu.org; Wed, 19 Nov 2014 09:55:02 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xr6ea-0000b4-K7 for qemu-devel@nongnu.org; Wed, 19 Nov 2014 09:54:53 -0500 Received: from mail-wi0-x230.google.com ([2a00:1450:400c:c05::230]:42170) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xr6ea-0000ar-Do for qemu-devel@nongnu.org; Wed, 19 Nov 2014 09:54:44 -0500 Received: by mail-wi0-f176.google.com with SMTP id ex7so5603379wid.9 for ; Wed, 19 Nov 2014 06:54:43 -0800 (PST) Sender: Paolo Bonzini Message-ID: <546CAF2F.4090103@redhat.com> Date: Wed, 19 Nov 2014 15:54:39 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <2A6E6B95B6E5C146ACE8440760E58185BDC31A5E@EXCHANGESERVER.schefczyk.local> <546C782E.9070803@redhat.com> <2A6E6B95B6E5C146ACE8440760E58185BDC31C30@EXCHANGESERVER.schefczyk.local> <546C8200.4070800@redhat.com> <2A6E6B95B6E5C146ACE8440760E58185BDC31C70@EXCHANGESERVER.schefczyk.local> <546C84C1.5000901@redhat.com> <2A6E6B95B6E5C146ACE8440760E58185BDC31CD0@EXCHANGESERVER.schefczyk.local> In-Reply-To: <2A6E6B95B6E5C146ACE8440760E58185BDC31CD0@EXCHANGESERVER.schefczyk.local> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] "File too large" error from "qemu-img snapshot" (was Re: AW: Bug Repoting Directions Request) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Prof. Dr. Michael Schefczyk" , qemu-devel On 19/11/2014 13:07, Prof. Dr. Michael Schefczyk wrote: > Yes! My level of knowledge is that one uses the qcow2 format in order > to be able to create live snapshots/backups. Otherwise one would tend > to use the more efficient raw format. Is this not correct and did I > apply the backup mechanism in the wrong way? That's correct, but you still have to create live snapshots from within QEMU. This is done with a QMP (QEMU Management Protocol) command like { "execute": "blockdev-snapshot-internal-sync", "arguments": { "device": "ide-hd0", "name": "snapshot0" } } QMP is accessed through normal sockets, or via libvirt. However, I'm not sure if running "qemu-img convert" on the resulting snapshot is possible though, and there is no equivalent of "qemu-img snapshot -d". You can instead use QEMU's support for backup, which will do what you wanted directly while the VM is running. For example: { "execute": "drive-backup", "arguments": { "device": "ide-hd0", "sync": "full", "format": "qcow2", "target": "backup.img" } } This does not even require qcow2 for the image. The downside is that you must not turn off the VM until the job has completed. Paolo