Thursday, July 9, 2015

How to Setup Hadoop 2.6.0 (Single Node Cluster) on CentOS/RHEL and Ubuntu

Apache Hadoop 2.6 significant improvements over the previous stable 2.X.Y releases. This version has many improvements in HDFS and MapReduce. This how to guide will help you to install Hadoop 2.6 on CentOS/RHEL 7/6/5 and Ubuntu System. This article doesn’t includes overall configuration of hadoop, we have only basic configuration required to start working with hadoop.
Hadoop on Linux

Step 1: Installing Java

Java is the primary requirement for running hadoop on any system, So make sure you have Java installed on your system using following command.
# java -version 

java version "1.8.0_31"
Java(TM) SE Runtime Environment (build 1.8.0_31-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.31-b07, mixed mode)
If you don’t have Java installed on your system, use one of following link to install it first.

Step 2: Creating Hadoop User

We recommend to create a normal (nor root) account for hadoop working. So create a system account using following command.
# useradd hadoop
# passwd hadoop
After creating account, it also required to set up key based ssh to its own account. To do this use execute following commands.
# su - hadoop
$ ssh-keygen -t rsa
$ cat ~/.ssh/ >> ~/.ssh/authorized_keys
$ chmod 0600 ~/.ssh/authorized_keys
Lets verify key based login. Below command should not ask for password but first time it will prompt for adding RSA to the list of known hosts.
$ ssh localhost
$ exit

Step 3. Downloading Hadoop 2.6.0

Now download hadoop 2.6.0 source archive file using below command. You can also select alternate download mirror for increasing download speed.
$ cd ~
$ wget
$ tar xzf hadoop-2.6.0.tar.gz
$ mv hadoop-2.6.0 hadoop

Step 4. Configure Hadoop Pseudo-Distributed Mode

4.1. Setup Environment Variables

First we need to set environment variable uses by hadoop. Edit ~/.bashrc file and append following values at end of file.
export HADOOP_HOME=/home/hadoop/hadoop
Now apply the changes in current running environment
$ source ~/.bashrc
Now edit $HADOOP_HOME/etc/hadoop/ file and set JAVA_HOME environment variable
export JAVA_HOME=/opt/jdk1.8.0_31/

4.2. Edit Configuration Files

Hadoop has many of configuration files, which need to configure as per requirements of your hadoop infrastructure. Lets start with the configuration with basic hadoop single node cluster setup. first navigate to below location
$ cd $HADOOP_HOME/etc/hadoop

Edit core-site.xml

Edit hdfs-site.xml


Edit mapred-site.xml

Edit yarn-site.xml


4.3. Format Namenode

Now format the namenode using following command, make sure that Storage directory is
$ hdfs namenode -format
Sample output:
15/02/04 09:58:43 INFO namenode.NameNode: STARTUP_MSG:
STARTUP_MSG: Starting NameNode
STARTUP_MSG:   host =
STARTUP_MSG:   args = [-format]
STARTUP_MSG:   version = 2.6.0
15/02/04 09:58:57 INFO common.Storage: Storage directory /home/hadoop/hadoopdata/hdfs/namenode has been successfully formatted.
15/02/04 09:58:57 INFO namenode.NNStorageRetentionManager: Going to retain 1 images with txid >= 0
15/02/04 09:58:57 INFO util.ExitUtil: Exiting with status 0
15/02/04 09:58:57 INFO namenode.NameNode: SHUTDOWN_MSG:
SHUTDOWN_MSG: Shutting down NameNode at

Step 5. Start Hadoop Cluster

Lets start your hadoop cluster using the scripts provides by hadoop. Just navigate to your hadoop sbin directory and execute scripts one by one.
$ cd $HADOOP_HOME/sbin/
Now run script.
Sample output:
15/02/04 10:00:34 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Starting namenodes on [localhost]
localhost: starting namenode, logging to /home/hadoop/hadoop/logs/
localhost: starting datanode, logging to /home/hadoop/hadoop/logs/
Starting secondary namenodes []
The authenticity of host ' (' can't be established.
RSA key fingerprint is 3c:c4:f6:f1:72:d9:84:f9:71:73:4a:0d:55:2c:f9:43.
Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '' (RSA) to the list of known hosts. starting secondarynamenode, logging to /home/hadoop/hadoop/logs/
15/02/04 10:01:15 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Now run script.
Sample output:
starting yarn daemons
starting resourcemanager, logging to /home/hadoop/hadoop/logs/
localhost: starting nodemanager, logging to /home/hadoop/hadoop/logs/

Step 6. Access Hadoop Services in Browser

Hadoop NameNode started on port 50070 default. Access your server on port 50070 in your favorite web browser.
hadoop single node namenode
Now access port 8088 for getting the information about cluster and all applications
hadoop single node applications
Access port 50090 for getting details about secondary namenode.
Hadoop single node secondary namenode
Access port 50075 to get details about DataNode

Step 7. Test Hadoop Single Node Setup

7.1 – Make the HDFS directories required using following commands.
$ bin/hdfs dfs -mkdir /user
$ bin/hdfs dfs -mkdir /user/hadoop
7.2 – Now copy all files from local file system /var/log/httpd to hadoop distributed file system using below command
$ bin/hdfs dfs -put /var/log/httpd logs
7.3 – Now browse hadoop distributed file system by opening below url in browser.
7.4 – Now copy logs directory for hadoop distributed file system to local file system.
$ bin/hdfs dfs -get logs /tmp/logs
$ ls -l /tmp/logs/