[libvirt] virStorageVolCreateXMLFrom

Daniel P. Berrange berrange at redhat.com
Mon Jun 22 09:08:39 UTC 2009


On Mon, Jun 22, 2009 at 09:59:00AM +0300, Kenneth Nagin wrote:
> 
> I'd like to get a better understanding of the virStorageVolCreateXMLFrom
> api Its name and signature imply that it is a cloning operation that copies
> a volume from one location to another. Is this correct?

Yes this method does a deep-copy of all the data, and can convert between
disk formats at the same time (eg raw -> qcow2, or any qemu-img format).

> Does it support remote copy of non-shared storage, e.g. from a http server?

It only supports copying within the same storage pool at this time, and
we don't implement any storage pool based on http. 

> Is there any thought about adding digest validation check, e.g. with a md5
> digest?

What would that do ? Or rather what semantics would you want from such a
thing ?  I rather hope that just reading & writing a local file would
not result in data corruption.

> Is copy-on-write cloning supported in this command?

No, you can create copy on write volumes using the <backingStore> element
in the XML description

http://libvirt.org/formatstorage.html#StorageVolBacking

This is supported for LVM volumes, qcow, qcow2 and vmdk files at this time.

Regards,
Daniel
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