'Return a tuple of the LDEV\'s Shadow Image pair status and info.'

def _get_vol_type_and_pair_info(self, ldev):

    ldev_info = self.get_ldev_info(['sts', 'vol_attr'], '-ldev_id', ldev)
    if (ldev_info['sts'] != NORMAL_STS):
        return (SMPL, None)
    if (THIN_ATTR in ldev_info['vol_attr']):
        return (PVOL, None)
    if (FULL_ATTR in ldev_info['vol_attr']):
        pair_info = self._get_full_copy_pair_info(ldev, 0)
        if (not pair_info):
            return (PVOL, None)
        if (pair_info['pvol'] != ldev):
            return (SVOL, pair_info)
        return (PVOL, None)
    return (SMPL, None)
