@Avinash C
See this description "The secondary NameNode merges the fsimage and the edits log files periodically and keeps edits log size within a limit. It is usually run on a different machine than the primary NameNode since its memory requirements are on the same order as the primary NameNode." The Checkpoint node periodically creates checkpoints of the namespace. It downloads fsimage and edits from the active NameNode, merges them locally, and uploads the new image back to the active NameNode. The Checkpoint node usually runs on a different machine than the NameNode since its memory requirements are on the same order as the NameNode. The Checkpoint node is started by bin/hdfs namenode -checkpoint on the node specified in the configuration file. The location of the Checkpoint (or Backup) node and its accompanying web interface are configured via the dfs.namenode.backup.address and dfs.namenode.backup.http-addressconfiguration variables. The start of the checkpoint process on the Checkpoint node is controlled by two configuration parameters. dfs.namenode.checkpoint.period, set to 1 hour by default, specifies the maximum delay between two consecutive checkpoints dfs.namenode.checkpoint.txns, set to 1 million by default, defines the number of uncheckpointed transactions on the NameNode which will force an urgent checkpoint, even if the checkpoint period has not been reached. The Checkpoint node stores the latest checkpoint in a directory that is structured the same as the NameNode's directory. This allows the checkpointed image to be always available for reading by the NameNode if necessary. See Import checkpoint.
... View more
