Re: [Qemu-devel] [RFC][PATCH v6 00/23] virtagent: host/guest RPC communication agent

[Jes Sorensen]

On 02/18/11 15:57, Anthony Liguori wrote:
> On 02/18/2011 08:30 AM, Jes Sorensen wrote:
>> However if there's an agent connection, it could be arranged in a way
>> allowing the host to reconnect to the guest agent. In that way it really
>> shouldn't be a big deal as long as our agent commands aren't too complex.
> 
> Oh, but they'll be nice and complex :-)  What happens if you do a live
> migration in the middle of doing a live backup?  You'll end up with the
> guest waiting to be told that it's okay to unfreeze itself only to never
> be told.

Well that isn't really different from the current setup - if QEMU
migrates, the admin tool has to connect to the new QEMU process and
issue the fsthaw command there instead.

> Terminating in QEMU means we can do intelligent things like delay live
> migration convergence, save state, etc.

We could easily add a flag for this in QEMU itself, so I don't see it
being a big issue.

Jes