Time for action – killing the NameNode process

Let's now kill the NameNode process, which we should expect to directly stop us from accessing HDFS and by extension, prevent the MapReduce jobs from executing:

Note

Don't try this on an operationally important cluster. Though the impact will be short-lived, it effectively kills the entire cluster for a period of time.

  1. Log onto the NameNode host and list the running processes:
    $ jps
    2372 SecondaryNameNode
    2118 NameNode
    2434 JobTracker
    5153 Jps
    
  2. Kill the NameNode process. Don't worry about SecondaryNameNode, it can keep running.
  3. Try to access the HDFS filesystem:
    $ hadoop fs -ls /
    11/12/13 16:00:05 INFO ipc.Client: Retrying connect to server: /10.0.0.100:9000. Already tried 0 time(s).
    11/12/13 16:00:06 ...

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