public void setClusterUp() throws KeeperException {
    byte[] upData = toByteArray();
    try {
      ZKUtil.createAndWatch(watcher, watcher.getZNodePaths().clusterStateZNode, upData);
    } catch (KeeperException.NodeExistsException nee) {
      ZKUtil.setData(watcher, watcher.getZNodePaths().clusterStateZNode, upData);
    }
  }
Sets the cluster as up.
@throws KeeperException unexpected zk exception
hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ClusterStatusTracker.java