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.
- Log onto the NameNode host and list the running processes:
$ jps 2372 SecondaryNameNode 2118 NameNode 2434 JobTracker 5153 Jps
- Kill the NameNode process. Don't worry about SecondaryNameNode, it can keep running.
- 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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