what are the differences zookeeper, journal node tasks and quorum journal manager in hadoop?

hadoop apache-zookeeper journal
Shashikanth Komandoor picture Shashikanth Komandoor · Sep 25, 2014 · Viewed 17.8k times · Source

On studying the material in multiple no of websites and videos, I am confused with the functionalities and differences in the purposes of the 3 hadoop components ZooKeeper, Journal Node and the Quorum Journal Manager.

Could anyone please explain me the reasons for inventing each of the above and differences in the purposes and functionalities of the above three components?

Thanks in advance.

Answer

Antariksha Yelkawar picture Antariksha Yelkawar · Sep 25, 2014

Think of it like this, zookeeper is a group of people, each assigned to watch over a factory and coordinate them, journal node is a place where all factory managers can check others status and coordinate. QJM is a combination of both to be used in HA for better coordination in case of fail over.

zookeeper coordinates hbase regionservers and other hadoop modules which require zookeeper.

journal node coordinates hadoop datanodes with the namenode.

QJM coordinates regionservers using the technique used by journal node

on core hadoop setup only journal node is necessary in case of distributed setup

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