Code review comment for lp:~renukaapte/nova/lp745340

I checked the changes and they look fine. We'd be better off by passing the volume id to the compute driver so that we would avoid the string manipulations. This is due to the fact that only dev_path and mountpoint are passed to driver->attach_volume (though dev_path contains the volume_id we are interested in). Changing the attach_volume signature would require a bit of work across the nova code (to make sure that other hypervisors are not affected), but a volume_id=None on the signature would be fine. I guess this could be carried out in another bug fix.