protected void startRs(ServerName server) throws IOException {
    getLogger().info("Starting regionserver {}", server.getAddress());
    cluster.startRegionServer(server.getHostname(), server.getPort());
    cluster.waitForRegionServerToStart(server.getHostname(), server.getPort(), startRsTimeout);
    getLogger().info("Started regionserver {}. Reported num of rs:{}", server.getAddress(),
      cluster.getClusterMetrics().getLiveServerMetrics().size());
  }
Returns current region servers - active master
hbase-it/src/test/java/org/apache/hadoop/hbase/chaos/actions/Action.java