Thanks very much Andrey! how can I figure out whether fsfreeze not succeed while taking snapshot, if I run a simple application inside VM, say mysql? thanks!
Best, Yuanzhen On Wed, Jul 16, 2014 at 5:25 PM, Andrey Korolyov <and...@xdel.ru> wrote: > On Thu, Jul 17, 2014 at 1:18 AM, Eric Blake <ebl...@redhat.com> wrote: > > On 07/16/2014 03:13 PM, Yuanzhen Gu wrote: > >> Hi folks, > >> > >> > >> I am going to make a patch, and need to find the pause and thaw(restore) > >> function before and after taking Live QEMU Snapshot respectively. > > > > Libvirt has the ability to do just that, when taking external disk-only > > snapshots. You can turn on libvirt debugging to trace what QMP/agent > > commands are sent during the overall snapshot operation. > > > >> > >> > >> Basically, I'm using # (qemu) snapshot_blkdev <blockX> > >> <snapshot-file><format> taking snapshot, > >> http://wiki.qemu.org/Features/Snapshots my profile tool didn't work > when > >> giving command inside QMP. > >> > >> > >> Does anyone know how to find the pause (freeze) and restore(thaw) > function > >> before and after taking snapshot? Or anyway using snapshot_blkdev > command > >> outside QEMU console? Thanks a lot in advance! > > > > You have to coordinate multiple commands: freeze to the guest agent, > > then snapshot to QMP, then thaw to the guest agent. > > > > -- > > Eric Blake eblake redhat com +1-919-301-3266 > > Libvirt virtualization library http://libvirt.org > > > > Just 2c: > > fsfreeze will not succeed if there are any container instances, for > example Docker, running in the VM on same filesystem. This exact case > can be fixed by extending agent` logic but it looks that the putting a > note is enough. > >
