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

HDFS health and FSCK


The health of the filesystem is very important for data retrieval and optimal performance. In a distributed system, it becomes more critical to maintain the good health of the HDFS filesystem so as to ensure block replication and near-parallel streaming of data blocks.

In this recipe, we will see how to check the health of the filesystem and do repairs, if any are needed.

Getting ready

Make sure you have a running cluster that has already been up for a few days with data. We can run the commands on a new cluster as well, but for the sake of this lab, it will give you more insights if it is run on a cluster with a large dataset.

How to do it...

  1. ssh to the master1.cyrus.com Namenode and change the user to hadoop.

  2. To check the HDFS root filesystem, execute the hdfs fsck / command, as shown in the following screenshot:

  3. We can also check the status of just one file instead of the entire filesystem, as shown in the following screenshot:

  4. The output of the fsck command will show the...