'Creates a volume and returns its UID.
Creates a volume with the specified name, and returns the UID that
the Storwize controller allocated for it.  We do this by executing a
create_volume and then calling into the simulator to perform an
lsvdisk directly.'

def _create_volume_and_return_uid(self, volume_name):

    volume = self._generate_vol_info()
    self.driver.create_volume(volume)
    return (volume, self._get_vdisk_uid(volume['name']))
