On Thu, Jul 17, 2014 at 1:48 AM, Yuanzhen Gu <yg...@cs.rutgers.edu> wrote: > 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. >> >
Just non-zero exit code from agent`s operation, not matter if you communicating directly via json exchange or via libvirt.