Re: [Qemu-devel] [PATCH] qcow3 - arbitrary metadata

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Jul 29, 2008 at 02:49:40AM +0100, Jamie Lokier wrote:
> Anthony Liguori wrote:
> > Can you provide more information about what the metadata is used for and 
> > why it's so important for the metadata to be in the image verses in a 
> > separate file?
> 
> Yeah, I have the opposite problem - too much in the same file :-)
> 
> I want to be able to savevm, but some of my VMs don't have any qcow2
> images (because I don't trust them for mission-critical VMs since
> recent discussion, or because they are floppy-only or CD-only VMs with
> no hard disk).
> 
> To enable savevm, at least according to docs, I have to have a qcow2
> image somewhere.  So I add a redundant minimum-size unpartitioned
> qcow2 hard disk and hope nobody minds...
> 
> That seems a bit hackish.  It would be nice if savevm could just write
> to a named file and loadvm could read it.

In libvirt we implement what I call 'unmanaged' save/restore to arbitrary 
files. We intend to add the QEMU style 'managed' save/restore to the 
disk image too. For the former we actually make use of the 'migrate'
command - we just migrate to/from a local file :-) It works pretty
nicely, so once Anthony gets KVM's migration support ported to plain
QEMU i'd recommend using that technique - conceivably we could have a
simple monitor command for making it easier to use in this scenario

Daniel
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