Book Image

Hadoop 2.x Administration Cookbook

By : Aman Singh
Book Image

Hadoop 2.x Administration Cookbook

By: Aman Singh

Overview of this book

Hadoop enables the distributed storage and processing of large datasets across clusters of computers. Learning how to administer Hadoop is crucial to exploit its unique features. With this book, you will be able to overcome common problems encountered in Hadoop administration. The book begins with laying the foundation by showing you the steps needed to set up a Hadoop cluster and its various nodes. You will get a better understanding of how to maintain Hadoop cluster, especially on the HDFS layer and using YARN and MapReduce. Further on, you will explore durability and high availability of a Hadoop cluster. You’ll get a better understanding of the schedulers in Hadoop and how to configure and use them for your tasks. You will also get hands-on experience with the backup and recovery options and the performance tuning aspects of Hadoop. Finally, you will get a better understanding of troubleshooting, diagnostics, and best practices in Hadoop administration. By the end of this book, you will have a proper understanding of working with Hadoop clusters and will also be able to secure, encrypt it, and configure auditing for your Hadoop clusters.
Table of Contents (20 chapters)
Hadoop 2.x Administration Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface
Index

Namenode troubleshooting


In this recipe, we will see how to find issues with Namenode and resolve them. As this is a recipe book, we will keep the theory to a minimum, but users must understand the moto behind the commands and how the mentioned tools work.

Getting ready

To step through the recipes in this chapter, make sure you have gone through the steps to install Hadoop cluster with HDFS and YARN enabled. Make sure to use Multi-node Hadoop cluster for better understanding and troubleshooting practice.

It is assumed that the user has basic knowledge about networking fundamentals, Linux commands, and filesystem.

How to do it...

Scenario 1: Namenode not starting due to permission issues on the Namenode directory.

  1. Connect to the master1.cyrus.com master node in the cluster and change to user hadoop.

  2. Try to write a test file to the location using the following command. If it succeeds, then the permissions are fine:

    $ touch /data/namenode1/test
    
  3. Otherwise, make sure the permission of the directory...