Book Image

Learning YARN

Book Image

Learning YARN

Overview of this book

Today enterprises generate huge volumes of data. In order to provide effective services and to make smarter and more intelligent decisions from these huge volumes of data, enterprises use big-data analytics. In recent years, Hadoop has been used for massive data storage and efficient distributed processing of data. The Yet Another Resource Negotiator (YARN) framework solves the design problems related to resource management faced by the Hadoop 1.x framework by providing a more scalable, efficient, flexible, and highly available resource management framework for distributed data processing. This book starts with an overview of the YARN features and explains how YARN provides a business solution for growing big data needs. You will learn to provision and manage single, as well as multi-node, Hadoop-YARN clusters in the easiest way. You will walk through the YARN administration, life cycle management, application execution, REST APIs, schedulers, security framework and so on. You will gain insights about the YARN components and features such as ResourceManager, NodeManager, ApplicationMaster, Container, Timeline Server, High Availability, Resource Localisation and so on. The book explains Hadoop-YARN commands and the configurations of components and explores topics such as High Availability, Resource Localization and Log aggregation. You will then be ready to develop your own ApplicationMaster and execute it over a Hadoop-YARN cluster. Towards the end of the book, you will learn about the security architecture and integration of YARN with big data technologies like Spark and Storm. This book promises conceptual as well as practical knowledge of resource management using YARN.
Table of Contents (20 chapters)
Learning YARN
Credits
About the Authors
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

Understanding ResourceManager's High Availability


The ResourceManager is a per-cluster service in a YARN cluster. It manages the cluster resources and schedules the applications on the basis of resource availability. What if this one service goes down or the node running the services gets out of the network? The whole cluster would become unusable, as the only point of contact for the clients is unavailable. Also, the running applications would not be able to acquire the cluster resources for task execution or status updates.

The ResourceManager service is considered to be the single point of failure in a cluster. In Hadoop 2.4.1, this issue is resolved and the High Availability feature of the ResourceManager service is introduced in YARN.

Architecture

A cluster configured with High Availability of ResourceManager has multiple ResourceManager services running; only one of them is active at a time and the rest are in standby state. Clients always connect to the active ResourceManager service...