Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm

[Dietmar Maurer]

> > 1.) qmp: savevm-start [statefile]
> >
> > This save the VM state into [statefile] and then stops the VM.
> 
> That's migrate exec:cat>statefile (or similar)

Basic functionality is the same, but we support saving state to block devices.

But there are many migration related patches in the last months,
so I decide to not touch that code for now, and write my own.

But yes, in future, we can try to merge things.

> > 2.) qga freezefs
> 
> How can freezefs run while the VM is stopped?

Oh, good point ;-)  So we need to call that inside savevm-start

> > 3.) create snapshots: either using external tools or by qmp:
> > snapshot-drive
> >
> > 4.) gqa unfreezefs
> 
> Same as above, this should be done after step (5).

yes
 
> > 5.) qmp: savevm-end
> >
> > This restarts/resumes the VM
> 
> That's simply "cont".

Yes - the plan was to do extra checks here. If it is not needed, we can remove 
it later.

I also want to avoid that a user can resume a VM which was suspended for taking 
snapshots,
but I am not sure how to do that.