[libvirt-users] how to detect if qemu supports live disk snapshot

[Eric Blake]

On 01/13/2014 04:57 AM, Francesco Romani wrote:

> 
> After reading from the docs, it seems that libvirt doesn't reports yet this information about
> the hypervisor in the capabilities XML: http://libvirt.org/formatcaps.html
> 
> a quick test against libvirt 1.1.3 (qemu 1.6.1) on Fedora 20 seems to confirm (see XML dump below[1]).

Correct.  It might indeed be a useful addition to the capability XML.

> 
> So, if I'm not mistaken, looks like the only way to test for the support in QEMU is to actually
> request a snapshot and see what happens.
> Is this right?

Unfortunately true for the moment.

> 
> If this is correct, I would like to craft and propose a patch to libvirt to export this information,
> maybe into a form of some kind of warning list/blacklist: disk snapshotting it is supposed to be
> available, but this particular QEMU doesn't support it.

Capability XML would be the proper way to expose this.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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