The running JVMs related to Hadoop can be displayed using the following command (use the correct Java installation location):

/usr/lib/jvm/java-7-oracle/bin/jps

The outcome of the preceding command is given in the following figure:

Active data nodes in the cluster can be displayed using the following command:

[Hadoop installation directory]/bin/hdfs dfsadmin –report

The outcome of the preceding command for a cluster with two data nodes is shown in the following figure:

Active node managers can be monitored using the following command:

 [Hadoop installation directory]/bin /yarn node –list

The outcome of the preceding command for a cluster with two node managers is shown in the following figure:

Apache Hadoop has provided Web UIs to monitor MapReduce job processing details.

As shown in the following figure, NameNode operations in HDFS can be monitored at http://localhost...