Thursday, January 18, 2018

5 Daemons of Hadoop

Hadoop is comprised of five separate daemons. Each of these daemon runs in its own JVM.

Daemons run on Master nodes:

NameNode – This daemon stores and maintains the metadata for HDFS.
Secondary NameNode – Performs housekeeping functions for the NameNode.
JobTracker – Manages MapReduce jobs, distributes individual tasks to machines running the Task Tracker.

 Daemons run on Slave nodes:

DataNode – Stores actual HDFS data blocks.
TaskTracker – Responsible for instantiating and monitoring individual Map and Reduce tasks.

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