protected void startDataNode(ServerName server) throws IOException {
    getLogger().info("Starting datanode {}", server.getHostname());
    cluster.startDataNode(server);
    cluster.waitForDataNodeToStart(server, startDataNodeTimeout);
    getLogger().info("Started datanode {}", server);
  }
Returns current region servers - active master
hbase-it/src/test/java/org/apache/hadoop/hbase/chaos/actions/Action.java