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Re: [Qemu-devel] Re: KVM call minutes for June 8
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] Re: KVM call minutes for June 8 |
Date: |
Wed, 9 Jun 2010 17:29:55 +0100 |
User-agent: |
Mutt/1.4.1i |
On Wed, Jun 09, 2010 at 11:22:55AM -0500, Anthony Liguori wrote:
> On 06/09/2010 10:31 AM, Daniel P. Berrange wrote:
> >> However, libvirt was counting on this feature and on the snapshot
> >> commands
> >>to switch from the text Monitor. We have two options:
> >>
> >> 1. Ask them to wait one more release (not so good for us)
> >> 2. Try to find a way to have those features in for 0.13
> >>
> >> Daniel has commented to me that making the snapshot commands synchronous
> >>for 0.13 wouldn't be that bad, what do you think?
> >>
> >The thought is that changing a command from synchronous to asynchronous is
> >not an ABI incompatible change. An existing app simply won't know to take
> >advantage of the new possibilities that async commands offer.
> >
>
> It's not QMP that's the major issue with savevm. The major issue is
> actually the way snapshots are saved in qcow2. You need to know the
> size of the snapshot prior to creating the snapshot which is not
> possible if you want to make snapshots live. In order to support this
> functionality, we'll probably have to introduce a new snapshot format in
> qcow2.
>
> Honestly, I would recommend not supporting snapshots in libvirt until we
> did the work to make snapshots live. Snapshots can cause guests to
> generate errors as it stands today and fixing that will almost certainly
> result in backwards compatibility considerations.
Libvirt already supports savevm in the text mode monitor, hence the desire
to have it work in QMP too.
> If we did put savevm in QMP today, we would need to provide an interface
> that let applications detect when we eventually fix this.
The problem you describe sounds like an internal qcow2 implementation
detail. The savevm related commands & their parameters don't have anything
that's inherantly tied to qcow2, so why would it affect QMP if qcow2 format
changed internally ?
Regards,
Daniel
--
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- [Qemu-devel] KVM call minutes for June 8, Chris Wright, 2010/06/08
- [Qemu-devel] Re: KVM call minutes for June 8, Anthony Liguori, 2010/06/08
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Luiz Capitulino, 2010/06/08
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Anthony Liguori, 2010/06/08
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Luiz Capitulino, 2010/06/09
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Daniel P. Berrange, 2010/06/09
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Anthony Liguori, 2010/06/09
- Re: [Qemu-devel] Re: KVM call minutes for June 8,
Daniel P. Berrange <=
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Kevin Wolf, 2010/06/10
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Anthony Liguori, 2010/06/10
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Kevin Wolf, 2010/06/10
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Avi Kivity, 2010/06/10
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Kevin Wolf, 2010/06/10
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Anthony Liguori, 2010/06/10
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Luiz Capitulino, 2010/06/11
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Anthony Liguori, 2010/06/11
- Re: [Qemu-devel] Re: KVM call minutes for June 8, Anthony Liguori, 2010/06/09