From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=52009 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OOuc8-0004IO-65 for qemu-devel@nongnu.org; Wed, 16 Jun 2010 11:33:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OOuc6-0001ns-V5 for qemu-devel@nongnu.org; Wed, 16 Jun 2010 11:33:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:14618) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OOuc6-0001ng-MF for qemu-devel@nongnu.org; Wed, 16 Jun 2010 11:33:14 -0400 Message-ID: <4C18EEAA.3060106@redhat.com> Date: Wed, 16 Jun 2010 17:32:58 +0200 From: Kevin Wolf MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH] monitor: Really show snapshot information about all devices References: <1276653214-15427-1-git-send-email-miguel.filho@gmail.com> <4C18C645.60200@redhat.com> <4C18CE5F.3090402@redhat.com> <20100616152249.GB2835@localhost.localdomain> In-Reply-To: <20100616152249.GB2835@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Chris Lalancette Cc: lcapitulino@redhat.com, Miguel Di Ciurcio Filho , armbru@redhat.com, qemu-devel@nongnu.org Am 16.06.2010 17:22, schrieb Chris Lalancette: > On 06/16/10 - 03:15:11PM, Kevin Wolf wrote: >> Am 16.06.2010 14:59, schrieb Miguel Di Ciurcio Filho: >>> On Wed, Jun 16, 2010 at 9:40 AM, Kevin Wolf wrote: >>>> >>>> If the human monitor was exactly what its name says, I'd happily apply >>>> this one (though I think it should be made clear from which image the VM >>>> state would be loaded). However, it isn't and I'm not sure if this >>>> wouldn't break libvirt. Dan, can you help? >>>> >>> >>> I didn't mention in the commit, but I've looked at libvirt's source >>> and it is not using 'info snapshots' AFAIK. >> >> Anthony, Dan, are you okay with the change then? > > Right, exactly as Miguel said, libvirt doesn't use "info snapshots" at all > at the moment. One of the reasons we don't use it at present is precisely > because it doesn't give us information about all disks in-use. > > The other reason that we can't use "info snapshots" is that we need to know > parent information about snapshots. That is, if you take a sequence of > snapshots: > > A -> B -> C > > And then you delete B, the disk changes from B will be merged automatically > into C to keep C a valid snapshot. However, there is currently no way to > discover this parent/child relationship, so we can't use "info snapshots" > for that reason as well. Well, there is no parent/child relation in qcow2, so exposing this is going to be really hard. We also don't really need it anywhere in qemu. What would libvirt use this information for? Kevin