Driver concept

Design goals

Stay within cinder driver framework
Build on top of cinder LVM driver for volume management

Key concept for volume transfer between hosts

Create new volume on attaching host via RPC, based on dm-clone target
Switch volume identities using _name_id property
Immediately return local connector on behalf of remote volume service
Supervise dm-clone target in a periodic job
- Clean-up when transfer is done
  - Load linear target
  - Remove connection and delete source volume
RPC can only carry limited information => side-channel required
- currently using volume admin metadata