'Find next available LUN number.
Returns a lun number greater than 0 which is not known to be in
use between the array and the specified host.'

def _get_first_available_lun_for_host(self, host):

    luns = self.list_luns_for_host(host)
    self._luns_in_use_by_host[host] = luns
    lun = 1
    while True:
        if (lun not in luns):
            return lun
        lun += 1
