Install hadoop in a single Cent-OS node

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1. Install Oracle Java. Steps can be learned from Install oracle java in Cent-OS
2. Create user account and password for hadoop using:

   sudo /sbin/useradd hadoop
   sudo /usr/bin/passwd hadoop

3. Configure key based login from hadoop to hadoop itself using:

   sudo su - hadoop
   ssh-keygen
   cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
   chmod 0600 ~/.ssh/authorized_keys
   #To test configuration, should echo hadoop
   ssh hadoop@localhost "echo $USER"
   exit

4. Download hadoop source from one of the mirrors linked at https://www.apache.org/dyn/closer.cgi/hadoop/common/ Download the latest stable .tar.gz release from stable folder. (Ex hadoop-1.2.1.tar.gz)
5. Extract hadoop sources in /opt/hadoop and make hadoop:hadoop its owner using:

   sudo mkdir /opt/hadoop
   cd /opt/hadoop/
   sudo tar xzf <path-to-hadoop-source>
   sudo mv hadoop-1.2.1 hadoop
   sudo chown -R hadoop:hadoop .

6. Configure hadoop for single node setup using:
   1. Login as user hadoop and change pwd to /opt/hadoop/hadoop using:

      sudo su - hadoop
      cd /opt/hadoop/hadoop

   2. Edit conf/core-site.xml and insert following within configuration tag:

      <property>
      <name>fs.default.name</name>
      <value>hdfs://localhost:9000/</value>
      </property>
      <property>
      <name>dfs.permissions</name>
      <value>false</value>
      </property>

   3. Edit conf/hdfs-site.xml and insert following within configuration tag:

      <property>
      <name>dfs.data.dir</name>
      <value>/opt/hadoop/hadoop/dfs/name/data</value>
      <final>true</final>
      </property>
      <property>
      <name>dfs.name.dir</name>
      <value>/opt/hadoop/hadoop/dfs/name</value>
      <final>true</final>
      </property>
      <property>
      <name>dfs.replication</name>
      <value>1</value>
      </property>

   4. Edit conf/mapred-site.xml and following within configuration tag:

      <property>
      <name>mapred.job.tracker</name>
      <value>localhost:9001</value>
      </property>

   5. Edit conf/hadoop-env.sh and do following changes:
      • Uncomment JAVA_HOME and set it to export JAVA_HOME=/opt/jdk1.7.0_40 or appropriate value based on installed java
      • Uncomment HADOOP_OPTS and set it to

        export HADOOP_OPTS=-Djava.net.preferIPv4Stack=true

7. Format namenode using:

   ./bin/hadoop namenode -format

8. Start all services using:

   ./bin/start-all.sh

9. Verify that all services got started using 'jps' command whose ouput should be similar to:

   26049 SecondaryNameNode
   25929 DataNode
   26399 Jps
   26129 JobTracker
   26249 TaskTracker
   25807 NameNode

   with different process-ids.

10. Try to access different services at:
    • http://localhost:50030/ for the Jobtracker
    • http://localhost:50070/ for the Namenode
    • http://localhost:50060/ for the Tasktracker
11. To stop all services use:

    ./bin/stop-all.sh

Steps learned from http://tecadmin.net/steps-to-install-hadoop-on-centosrhel-6/

Verify hadoop installation by running a map-reduce job

We will try to run hadoop wordcount example on large text file to verify hadoop is functioning properly:

1. Download large text file using:

   wget http://www.gutenberg.org/cache/epub/132/pg132.txt

   in /opt/hadoop/data

2. Verify that all hadoop services are running using jps. If they are not running use ../hadoop/bin/start-all.sh to start everything.
3. Copy file from local filesystem to hdfs using:

   ../hadoop/bin/hadoop dfs -copyFromLocal pg132.txt /user/hduser/input/pg132.txt

4. Verify file got copied using:

   ../hadoop/bin/hadoop dfs -ls /user/hduser/input

   Note you can find more dfs commands using:

   ../hadoop/bin/hadoop dfs help

5. Open various hadoop web UIs in different browser tabs:

   http://localhost:50030/

   Shows number of map / reduce processes

   http://localhost:50060/

   Shows number of hadoop tasks being executed

   http://localhost:50070/

   Shows number of live nodes and also provides a file browser to browse hdfs

6. Start hadoop job using:

   ../hadoop/bin/hadoop jar ../hadoop/hadoop-examples-1.2.1.jar wordcount /user/hduser/input/pg132.txt /user/hduser/output/wordcount

   The examples jar version might be different from 1.2.1 based on installed version of hadoop.

7. Check the output using:

   ../hadoop/bin/hadoop dfs -cat /user/hduser/output/wordcount/p* | less

Steps learned from https://giraph.apache.org/quick_start.html

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