Re: [PATCH 2/6] migration: introduce savevm, loadvm, delvm QMP commands

[Peter Krempa]

On Tue, Jul 07, 2020 at 12:33:31 +0200, Kevin Wolf wrote:
> Am 07.07.2020 um 08:38 hat Peter Krempa geschrieben:
> > On Mon, Jul 06, 2020 at 18:15:55 +0200, Kevin Wolf wrote:
> > > Am 03.07.2020 um 18:02 hat Daniel P. Berrangé geschrieben:

[...]

> > IMO we really want this also for external snapshots. Driving the
> > migration as standard migration is really suboptimal especially when the
> > user wants minimal downtime. Transactioning a post-copy style copy-on
> > write migration would simplify this a lot. I agree though that this is
> > for a different conversation.
> 
> This is an interesting point actually. And while the implementation of
> the post-copy style live snapshotting is for a different conversation, I
> think the implications it has on the API are relevant for us now.
> 
> But even if we have an all-in-one snapshot job instead of a transaction
> to group all the individual operations together, I think you could still
> represent that by just specifying an empty list of nodes to be
> snapshotted. (I feel this is another argument for passing the nodes to
> include rather than nodes to exclude from the disk snapshot.)

Definitely. From libvirt's POV it's IMO simpler and more future-proof to
enumerate everything rather than keep a database of what to skip.