@Override
  public SetBalancerRunningResponse setBalancerRunning(RpcController c,
    SetBalancerRunningRequest req) throws ServiceException {
    try {
      server.checkInitialized();
      boolean prevValue = (req.getSynchronous())
        ? synchronousBalanceSwitch(req.getOn())
        : server.balanceSwitch(req.getOn());
      return SetBalancerRunningResponse.newBuilder().setPrevBalanceValue(prevValue).build();
    } catch (IOException ioe) {
      throw new ServiceException(ioe);
    }
  }
Turn on/off snapshot auto-cleanup based on TTL
@param enabledNewVal Set to <code>true</code> to enable, <code>false</code> to disable
@param synchronous   If <code>true</code>, it waits until current snapshot cleanup is
                     completed, if outstanding
@return previous snapshot auto-cleanup mode
hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterRpcServices.java