public void setClusterDown() throws KeeperException {
    try {
      ZKUtil.deleteNode(watcher, watcher.getZNodePaths().clusterStateZNode);
    } catch (KeeperException.NoNodeException nne) {
      LOG.warn("Attempted to set cluster as down but already down, cluster " + "state node ("
        + watcher.getZNodePaths().clusterStateZNode + ") not found");
    }
  }
Sets the cluster as down by deleting the znode.
@throws KeeperException unexpected zk exception
hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ClusterStatusTracker.java