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 – getting web server data into Hadoop


Let's take a look at how we can simplistically copy data from a web server onto HDFS.

  1. Retrieve the text of the NameNode web interface to a local file:

    $ curl localhost:50070 > web.txt
    
  2. Check the file size:

    $ ls -ldh web.txt 
    

    You will receive the following response:

    -rw-r--r-- 1 hadoop hadoop 246 Aug 19 08:53 web.txt
    
  3. Copy the file to HDFS:

    $ hadoop fs -put web.txt web.txt
    
  4. Check the file on HDFS:

    $ hadoop fs -ls 
    

    You will receive the following response:

    Found 1 items
    -rw-r--r--   1 hadoop supergroup        246 2012-08-19 08:53 /user/hadoop/web.txt
    

What just happened?

There shouldn't be anything that is surprising here. We use the curl utility to retrieve a web page from the embedded web server hosting the NameNode web interface and save it to a local file. We check the file size, copy it to HDFS, and verify the file has been transferred successfully.

The point of note here is not the series of actions—it is after all just another...