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

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.