From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: KVM management and API Date: Fri, 27 Apr 2007 17:23:31 -0500 Message-ID: <463277E3.5070305@codemonkey.ws> References: <798858.14143.qm@web35807.mail.mud.yahoo.com> <20070427220657.GB8384@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel To: "Daniel P. Berrange" Return-path: In-Reply-To: <20070427220657.GB8384-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Daniel P. Berrange wrote: >> 5. Snapshots : where are snapshots saved ? I tried savevm with /tmp/x, I was expecting a >> file containing memory image... do these work differrently ? >> Also, when one does loadvm, is the snapshot gone ? I mean can one restore the same >> snapshot multiple times ? >> > > libvirt has APIs for snapshotting, but we've not implement them for QEMU > or KVM yet. You can save the file to any location you have write permissions > for. Its not a plain memory image because it also contains info about the > state of all the various virtual devices. > > The snapshot doesn't deal with changes in state on your disks. So if you restored > a snapshot, ran it for a while doing disk IO and then quit & tried to restore the > snapshot again your disks would be out of sync. > > That said if one could take snapshots of the disks (eg with LVM, or QCOW) then > it ought to be possible to use a snapshot multiple times over. > With QEMU 0.9.0 (and by extension, KVM), snapshots are actually stored as part of the disk image with qcow2. This allows you to have a consistent snapshot that includes CPU state and disk state. Regards, Anthony Liguori > Dan. > ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/