[libvirt-users] RBD images locking

[NEVEU Stephane]

De : Daniel P. Berrange [mailto:berrange at redhat.com] 
Envoyé : vendredi 8 novembre 2013 06:32
À : Eric Blake
Cc : NEVEU Stephane; libvirt-users at redhat.com
Objet : Re: [libvirt-users] RBD images locking

On Thu, Nov 07, 2013 at 09:08:58AM -0700, Eric Blake wrote:
> On 11/07/2013 09:04 AM, NEVEU Stephane wrote:
> > Eric,
> 
> [please don't top-post on technical lists]
> 
> > 
> > Well, in case where several servers may start the same virtual machines after a reboot for exemple.
> > http://lists.ceph.com/pipermail/ceph-users-ceph.com/2013-August/0038
> > 87.html
> 
> Isn't the existing virtlockd support already sufficient for this?  If 
> not, what is preventing the virtlock framework from interacting with 
> rbd disks?

>Nothing really. The current impl only deals with disks with type=file or type=block, ignoring type=network. We could extend it to cope with the latter though - either using a URI to uniquely identify the >network storage, or better yet using some unique volume ID if available.

Yes it might be useful when not using an orchestrator. Can't we use the "block_name_prefix" of a volume to do so ? It seems to be unique and to be the entry point  to identify an image (via objects) across a pool :

rbd -p mypool info myvm

rbd image 'myvm'
	Size 10240 MB in 2560 objects
	Order 22 (4096 kB objects)
	block_name_prefix: rb.0.11a6.238e1f29
	format: 1

rados -p mypool ls | grep ^rb.0.11a6.238e1f29 | wc -l
630 objects