private TSStatus checkClusterProtocol() {
    TSStatus status = new TSStatus(TSStatusCode.SUCCESS_STATUS.getStatusCode());
    if (CONF.getDataRegionConsensusProtocolClass().equals(SIMPLE_CONSENSUS)
        || CONF.getSchemaRegionConsensusProtocolClass().equals(SIMPLE_CONSENSUS)) {
      status.setCode(TSStatusCode.REMOVE_DATANODE_ERROR.getStatusCode());
      status.setMessage("SimpleConsensus protocol is not supported to remove data node");
    }
    return status;
  }
Checks the cluster protocol. Removing a DataNode is not supported in standalone mode.

@return SUCCEED_STATUS if the cluster is not in standalone mode, REMOVE_DATANODE_FAILED
    otherwise
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/procedure/env/RemoveDataNodeHandler.java