'Create a snap vx of a source and copy to a target.
:param array: the array serial number
:param source_device_id: source volume device id
:param target_device_id: target volume device id
:param snap_name: the name for the snap shot
:param extra_specs: extra specifications
:param create_snap: Flag for create snapvx'

def create_volume_replica(self, array, source_device_id, target_device_id, snap_name, extra_specs, create_snap=False):

    start_time = time.time()
    if create_snap:
        self.create_volume_snapvx(array, source_device_id, snap_name, extra_specs)
    self.rest.modify_volume_snap(array, source_device_id, target_device_id, snap_name, extra_specs, link=True)
    LOG.debug('Create    element    replica    took:    %(delta)s    H:MM:SS.', {'delta': self.utils.get_time_delta(start_time, time.time())})
