On Fri, Feb 05, 2016 at 11:28:42AM +0300, Denis V. Lunev wrote:
> On 02/03/2016 11:14 AM, Fam Zheng wrote:
> >On Sat, 01/30 13:56, Vladimir Sementsov-Ogievskiy wrote:
> >>Hi all.
> >>
> >>These series which aims to add external backup api. This is needed to allow
> >>backup software use our dirty bitmaps.
> >>
> >>Vmware and Parallels Cloud Server have this feature.
> >What is the advantage of this appraoch over "drive-backup sync=incremental
> >..."?
> 
> This will allow third-party vendors to backup QEMU VMs into
> their own formats or to the cloud etc.

Backup software can implement NBD to receive the incremental blocks from
QEMU.  Use drive-backup sync=incremental and the backup appliance as the
NBD target.

It's more complicated to add this QMP command flow to backup software
than to implement NBD.

Stefan