Re: [Qemu-devel] [PATCH v2 0/6] external backup api

[Denis V. Lunev]

On 02/09/2016 05:21 PM, Stefan Hajnoczi wrote:
> 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
it can, but this is a matter of problem due to the nature of
how this software is implemented. Usually it is written
in a semi-standard way and it uses "plugins" to actually
collect the data, i.e. the code is written in standard
interface/real implementation pattern and interfaces are
basically the same.

With this standard approach backup software is working
as an active side of the process, i.e. it performs operations
and controls the flow.

This means that "non-standard" QEMU technology will be
pain here.

Den