Re: [libvirt] Quorum block driver libvirt support proposal

On 05/16/2014 07:54 AM, Daniel P. Berrange wrote: >> <disk type='quorum' device='disk'> >> <driver name='qemu' type='quorum'/> >> <threshold value=2/> >> <backingStore type='file'> >> <format type='qcow2'/> >> <source file='/var/lib/libvirt/images/file1.qcow2'/> >> </backingStore> >> <backingStore type='file'> >> <format type='qcow2'/> >> <source file='/var/lib/libvirt/images/file2.qcow2'/> >> </backingStore> >> <backingStore type='file'> >> <format type='qcow2'/> >> <source file='/var/lib/libvirt/images/file3.qcow2'/> >> </backingStore> >> <target dev='vda' bus='virtio'/> >> </disk> > > It feels rather odd to have <backingStore> elements but no top level > disk images. Really these are all top level images Unfortunately, we are allowed to have a quorum with mixed-mode sources - I could have a quorum where file 1 is a local file, file 2 is a block device, and file 3 is a gluster protocol. But since we encode the type of file at the <disk type='...'> level, there is NO way to list three different <source> elements for those three quorum members. I think Benoit's proposal makes sense - a quorum is a node in the backing chain with NO <source> element, but instead has MULTIPLE <backingStore> elements.