RAID alert messages.

        [available/used] means that ideally the array may have _available_
        devices however, _used_ devices are in use.
        Obviously when used >= available then things are good.

def raid_alert(self, status, used, available, type):
        """RAID alert messages.

        [available/used] means that ideally the array may have _available_
        devices however, _used_ devices are in use.
        Obviously when used >= available then things are good.
        """
        if type == 'raid0':
            return 'OK'
        if status == 'inactive':
            return 'CRITICAL'
        if used is None or available is None:
            return 'DEFAULT'
        elif used < available:
            return 'WARNING'
        return 'OK'