Re: [libvirt] RFC: using a network device as a destination for a disk snapshot
On 10/30/2013 10:44 AM, Eric Blake wrote:
Here's the XML I think we need to add to domainsnapshot:
<domainsnapshot>
...
<disks>
<disk name='vda' snapshot='external' type='network'>
<driver type='qcow2'/>
<source protocol='gluster' name='vol1/img2'>
<host name='red'/>
</source>
</disk>
that is, add an optional /disk@type attribute (if absent, it defaults to
type='file'), and where if present, the <source> subelement then takes
on alternate forms in the same manner in which //domain/devices/disk
handles alternates (here, allowing a protocol, name, and host
specification).
[Ultimately, we need to fix //domain/devices/disk to specify a full
backing chain, but one step at a time...]
This does match the XML that my (prototype) Nova code generated in hopes
that this would work, except that I didn't have a <driver> element.
(Makes sense, I can add this.)
<domainsnapshot>
<disks>
<disk name="vdb" snapshot="external"
type="network">
<source protocol="gluster"
name="gvol1/volume-931536e0-65a7-4bd9-85ed-48bdd0160642.f6e62e4c-17b9-49bd-8941-10e8d11a22ca">
<host name="127.0.0.1"/>
</source>
</disk>
<disk
name="/opt/stack/data/nova/instances/6ff2075e-7b23-492a-865a-e7f8269d95bb/disk"
snapshot="no"/>
</disks>
</domainsnapshot>
$ qemu-img info
volume-931536e0-65a7-4bd9-85ed-48bdd0160642.f6e62e4c-17b9-49bd-8941-10e8d11a22ca
image:
volume-931536e0-65a7-4bd9-85ed-48bdd0160642.f6e62e4c-17b9-49bd-8941-10e8d11a22ca
file format: qcow2
virtual size: 1.0G (1073741824 bytes)
disk size: 193K
cluster_size: 65536
backing file: volume-931536e0-65a7-4bd9-85ed-48bdd0160642
backing file format: raw