Re: [Qemu-devel] [question] incremental backup a running vm

[Zhang Haoyu]

On 2015-01-26 17:29:43, Paolo Bonzini wrote:
>
> On 26/01/2015 02:07, Zhang Haoyu wrote:
> > Hi, Kashyap
> > I've tried ‘drive_backup’ via QMP,
>> but the snapshots were missed to backup to destination,
> > I think the reason is that backup_run() only copy the
> > guest data regarding qcow2 image.
> 
>Yes, that's the case.
> 
> QEMU cannot still access internal snapshots while the file is open.
> External snapshots are opened read-only, and can be copied with "cp"
> while QEMU is running.
Thanks, Paolo,
but too many internal snapshots were saved by customers,
switching to external snapshot mechanism has significant impaction
on subsequent upgrade.

Another problem:
drive_backup just implement one time backup,
but I want VMWare's VDP-like backup mechanism.
The initial backup of a virtual machine takes comparatively more time,
because all of the data for that virtual machine is being backed up. 
Subsequent backups of the same virtual machine take less time, because
changed block tracking (log dirty) mechanism is used to only backup the dirty 
data.
After inittial backup done, even the VM shutdown, but subsequent backup also 
only 
copy the changed data.

Thanks,
Zhang Haoyu
>
> Paolo