Configure a federation with a cluster upgrade
Hortonworks Data Platform versions starting with 3.0.0 support HDFS federations. You can configure the federation as you upgrade your cluster.
hdfs start namenodecommand during the upgrade process as specified.
hdfs start namenode --config $HADOOP_CONF_DIR -upgrade -clusterId <cluster_ID>
If you do not specify the Cluster ID, then a unique ID is auto-generated.