[ovirt-devel] [VDSM] Live snapshot with ceph disks

[Christopher Pereira]

Hi Nir,

Regarding "3. Engine creates snapshot *via cinder*"...

What are the benefits of creating snapshots via cinder vs via libvirt?

Libvirt and qemu are offering core VM-aware storage and memory snapshot features.
Besides, snapshot-create-as has no VM downtime.
It would be a mistake to implement snapshoting on the ceph layer.
At some point, you would need VM-aware code (eg: the VM memory state) and organically go back to the libvirt + qemu way.
There seems to be qemu + libvirt support for ceph snapshots (via rbd commands) which probably offers some (?) VM-awareness, but what are the benefits of not using the good old core libvirt + qemu snapshot features?
I must be missing something...

2) Not related:

It seems like oVirt shifted focus towards Ceph recently...

I would like to drop Gluster for Ceph if the latter supports SEEK HOLE reading and optimal sparse files operations. Can someone please confirm if Ceph is supporting SEEK_HOLE? I saw some related code, but would like to ask for comments before setting up and benchmarking Ceph sparse image file operations.