Re: [Qemu-devel] [PATCH V2 09/12] qmp: add interface blockdev-snapshot-delete-internal-sync

[Stefan Hajnoczi]

On Mon, Jun 17, 2013 at 11:25:26AM +0800, Wenchao Xia wrote:
> 于 2013-6-15 17:55, Eric Blake 写道:
> >Should this command be made available via 'transaction'?  That is, if I
> >have a two-disk VM, and use 'transaction' to take a snapshot of both
> >disks at once, shouldn't I also have a way to delete the snapshots of
> >both at once, or gracefully fail without data loss if the second one has
> >problems?
> 
>   I think adding it in transaction is not very useful but brings more
> complexity. Transcation is used to guareentee all operations are taken
> in one time point, for example, snapshot creation use it to make sure
> all are consistent to VM. But for deletion, this requirement do not
> exist.

I guess the problem is: can we make internal snapshot deletion
transactional?  It's hard to do rollback for snapshot deletion.

But batching is definitely useful for doing 'delvm' in QMP.  I just
don't think transactions help.  We just need a 'delvm' equivalent in
QMP.

Stefan