Book Image

Hadoop Beginner's Guide

Book Image

Hadoop Beginner's Guide

Overview of this book

Data is arriving faster than you can process it and the overall volumes keep growing at a rate that keeps you awake at night. Hadoop can help you tame the data beast. Effective use of Hadoop however requires a mixture of programming, design, and system administration skills."Hadoop Beginner's Guide" removes the mystery from Hadoop, presenting Hadoop and related technologies with a focus on building working systems and getting the job done, using cloud services to do so when it makes sense. From basic concepts and initial setup through developing applications and keeping the system running as the data grows, the book gives the understanding needed to effectively use Hadoop to solve real world problems.Starting with the basics of installing and configuring Hadoop, the book explains how to develop applications, maintain the system, and how to use additional products to integrate with other systems.While learning different ways to develop applications to run on Hadoop the book also covers tools such as Hive, Sqoop, and Flume that show how Hadoop can be integrated with relational databases and log collection.In addition to examples on Hadoop clusters on Ubuntu uses of cloud services such as Amazon, EC2 and Elastic MapReduce are covered.
Table of Contents (19 chapters)
Hadoop Beginner's Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Time for action – swapping to a new NameNode host


In the following steps we keep the new configuration files on an NFS share mounted to /share/backup and change the paths to match where you have the new files. Also use a different string to grep; we use a portion of the IP address we know isn't shared with any other host in the cluster.

  1. Log on to the current NameNode host and shut down the cluster.

    $ stop-all.sh
    
  2. Halt the host that runs the NameNode.

    $ sudo poweroff
    
  3. Log on to the new NameNode host and confirm the new configuration files have the correct NameNode location.

    $ grep 110 /share/backup/*.xml
    
  4. On the new host, first copy across the slaves file.

    $ cp /share/backup/slaves Hadoop/conf
    
  5. Now copy across the updated configuration files.

    $ cp /share/backup/*site.xml Hadoop/conf
    
  6. Remove any old NameNode data from the local filesystem.

    $ rm -f /var/Hadoop/dfs/name/*
    
  7. Copy the updated configuration files to every node in the cluster.

    $ slaves.sh cp /share/backup/*site.xml Hadoop/conf
    
  8. Ensure each...