'Returns any existing instance in the @sc-volumecreator group that\'s
located in zone.'

def _get_existing_instance(self, zone):

    active_states = ['pending', 'running']
    i = self._host_instance
    if (i and self._validate_host_instance(i, zone)):
        log.info(('Using    specified    host    instance    %s' % i.id))
        return i
    for node in self.nodes:
        if ((node.state in active_states) and (node.placement == zone)):
            log.info(('Using    existing    instance    %s    in    group    %s' % (node.id, self.cluster_group.name)))
            return node
