From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59353) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UgwxM-0008FH-24 for qemu-devel@nongnu.org; Mon, 27 May 2013 08:55:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UgwxJ-0006HW-R0 for qemu-devel@nongnu.org; Mon, 27 May 2013 08:55:19 -0400 Received: from mail-ee0-f42.google.com ([74.125.83.42]:41772) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UgwxJ-0006HQ-HS for qemu-devel@nongnu.org; Mon, 27 May 2013 08:55:17 -0400 Received: by mail-ee0-f42.google.com with SMTP id c50so4106359eek.29 for ; Mon, 27 May 2013 05:55:16 -0700 (PDT) Date: Mon, 27 May 2013 14:55:13 +0200 From: Stefan Hajnoczi Message-ID: <20130527125513.GF23204@stefanha-thinkpad.redhat.com> References: <20130525082911.27253.67454.malonedeb@gac.canonical.com> <20130525082911.27253.67454.malonedeb@gac.canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130525082911.27253.67454.malonedeb@gac.canonical.com> Subject: Re: [Qemu-devel] [Bug 1184089] [NEW] [Feature request] loadvm snapshot as read-only List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Bug 1184089 <1184089@bugs.launchpad.net> Cc: qemu-devel@nongnu.org On Sat, May 25, 2013 at 08:29:11AM -0000, Michael Coppola wrote: > There are many ways to take and manage snapshots in QEMU, but one main > feature that's missing is the ability to 'loadvm' a LIVE snapshot and > have all future changes redirected to a temporary file. This would > effectively be combining the -loadvm and -snapshot switches and make the > snapshot read-only. With this feature, users would be provided a > "sandbox" and be able to start and restart the same live snapshot > without corrupting the image in doing so. This should be possible soon. Wenchao Xia is working on new monitor commands that allow you to combine internal snapshots (loadvm/savevm) with external snapshots (blockdev-snapshot-sync). You would submit a QMP 'transaction' command that specifies a loadvm followed by a blockdev-snapshot-sync. This operation is atomic. Note that internal snapshots do not destroy the snapshot. Therefore, when you loadvm an internal snapshot and write to the disk, you are not modifying the internal snapshot only the current state of the disk. You can loadvm it again later. Stefan