From the perspective of functionality, a Hadoop cluster is composed of an HDFS cluster and a MapReduce cluster. The HDFS cluster consists of the default filesystem for Hadoop. It has one or more NameNodes to keep track of the filesystem metadata, while actual data blocks are stored on distributed slave nodes managed by DataNode . Similarly, a MapReduce cluster has one JobTracker daemon on the master node and a number of TaskTrackers on the slave nodes. The JobTracker manages the life cycle of MapReduce jobs. It splits jobs into smaller tasks and schedules the tasks to run by the TaskTrackers. A TaskTracker executes tasks assigned by the JobTracker in parallel by forking one or a number of JVM processes. As a Hadoop cluster administrator, you will be responsible for managing both the HDFS cluster and the MapReduce cluster.
In general, system administrators should maintain the health and availability of the cluster. More specifically, for an HDFS cluster, it means the management...