[libvirt] virStorageVolCreateXML vs virStorageVolCloneXML

[Daniel P. Berrange]

On Fri, Jul 18, 2008 at 12:27:49PM +0200, Stefan de Konink wrote:
> Hi,
> 
> There is currently no implementation in the api to clone snapshots or
> images. I wonder if we could add an XML node to specify a backed device.
> Or add a new function that allows to clone.

I think this wants to be done with a new API, taking a source volume,
and destination pool as the arguemnts. Something along the lines of


    virStorageVolClone(virStorageVolPtr src,
                       virStoragePoolPtr dst,
                       unsigned int flags);

Although the common & efficient case will be cloning volumes in the
same pool, allowing a pool to be passed in directly, allows us to 
clone across pools. eg, clone a LVM volume to a NFS file.

> Like the create is not supported by all pools, cloning should also be
> based on best effort, falling back to cp for non sparse images. (Probably
> a good configuration option)

Basically pool which supports 'create' ought to be usable as a destination
pool - at worst we can do a generic 'cp' style clone if the underlying
pool doesn't have a more efficient method.


Daniel
-- 
|: Red Hat, Engineering, London   -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org  -o-  http://virt-manager.org  -o-  http://ovirt.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|