public static void setClusterId(ZKWatcher watcher, ClusterId id) throws KeeperException {
    ZKUtil.createSetData(watcher, watcher.getZNodePaths().clusterIdZNode, id.toByteArray());
  }
Publishes and synchronizes a unique identifier specific to a given HBase cluster. The stored
identifier is read from the file system by the active master on startup, and is subsequently
available to all watchers (including clients).
hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKClusterId.java