Scaling Namespaces and Optimizing Data Storage
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Add a NameNode to an existing HDFS cluster

Adding a NameNode HA to an existing cluster with federated NameNodes requires updating the cluster configuration, propagating the update to all the nodes in the cluster, starting the new NameNodes, and refreshing the DataNodes to identify the new NameNodes.

  1. Add dfs.nameservices to hdfs-site.xml of the NameNodes that you want to include in the federation.
  2. For the active NameNode and its corresponding standby node, update the configuration with the NameService ID suffix.
  3. Add the configuration for the new NameNodes to the cluster configuration file.
    For more information about steps 1, 2, and 3; see .
  4. Propagate the configuration file updates to all the nodes in the cluster.
  5. Start the new active NameNode and its standby node.
  6. Refresh the DataNodes in the cluster to identify the new NameNodes.
    hdfs dfsadmin -refreshNamenodes <datanode_host_name>:<datanode_rpc_port>