'Migrate the volume to the specified host.
Returns a boolean indicating whether the migration occurred, as well as
model_update.
:param context: Context
:param volume: A dictionary describing the volume to migrate
:param host: A dictionary describing the host to migrate to, where
host[\'host\'] is its name, and host[\'capabilities\'] is a
dictionary of its reported capabilities.'

@abc.abstractmethod
def migrate_volume(self, context, volume, host):

    return (False, None)
