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

Datanode recovery – disk full


In this recipe, we will discuss on the process to recover the Datanode once it is low on disk space. Usually, Datanodes are assumed to fail in the cluster, but sometimes it is important to know how to recover in case of the disk being full.

This is a process which we have to perform when the replication factor is set to 1 and we have critical data to recover.

If the disk on the Datanode is bad and it cannot be read due to hardware issues such as controller failure, then we cannot follow this process. On the Datanode, which is low on disk space, we will add a new larger disk and mount it on the Datanode and start the Datanode daemon for the blocks that are available.

One thing we need to know here is that once we shutdown the Datanode, how quickly the Namenode sees it being removed from the cluster. Remember, we are not decommissioning the node, but trying to replace the disk and start the Datanode service back, without movement of blocks of the Datanode.

This could...