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 roll edits – offline mode


In this recipe, we will look at how to roll edits in offline mode. What if the Namenode disk is completely full and it is not able to start at all? We cannot use the process described in the precious recipe.

For this, we will use another Namenode, mount the NFS mount there, and perform the process there.

Getting ready

For this recipe, make sure you have completed the recipe on Hadoop cluster setup, Chapter 1, Hadoop Architecture and Deployment, and has one more node to use as just Namenode.

How to do it...

  1. Connect to the master1.cyrus.com master node and switch to user root.

  2. Unmount the NFS share, which is used as a directory to store the metadata as shown in the following screenshot:

  3. Again, we are keeping the other mount point /data/namenode1 safe this time and just playing around with /data/namenode2.

  4. Mount the NFS share on the master2.cyrus.com node using the following command:

    # mount –t nfs4 filer.cyrus.com:/nfs /mnt
    
  5. On master2, create a directory owned by...