Steps to Install Hadoop on CentOS/RHEL 6---reference

http://tecadmin.net/steps-to-install-hadoop-on-centosrhel-6/#

The Apache Hadoop software library is a framework that allows for the distributed processing of large data sets across clusters of computers using simple programming models. Read More

This article will help you for step by step install and configure single node hadoop cluster.

Step 1. Install Java

Before installing hadoop make sure you have java installed on your system. If you do not have java installed use following article to install Java.

Steps to install JAVA on CentOS and RHEL 5/6

Step 2. Create User Account

Create a system user account to use for hadoop installation.

# useradd hadoop
# passwd hadoop

Changing password for user hadoop.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

Step 3. Configuring Key Based Login

Its required to setup hadoop user to ssh itself without password. Using following method it will enable key based login for hadoop user.

# su - hadoop
$ ssh-keygen -t rsa
$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
$ chmod 0600 ~/.ssh/authorized_keys
$ exit

Step 4. Download and Extract Hadoop Source

Downlaod hadoop latest availabe version from its official site, and follow below steps.

# mkdir /opt/hadoop
# cd /opt/hadoop/
# wget http://apache.mesi.com.ar/hadoop/common/hadoop-1.2.1/hadoop-1.2.1.tar.gz
# tar -xzf hadoop-1.2.1.tar.gz
# mv hadoop-1.2.1 hadoop
# chown -R hadoop /opt/hadoop
# cd /opt/hadoop/hadoop/

Step 5: Configure Hadoop

First edit hadoop configuration files and make following changes.
5.1 Edit core-site.xml

# vim conf/core-site.xml

#Add the following inside the configuration tag
<property>
    <name>fs.default.name</name>
    <value>hdfs://localhost:9000/</value>
</property>
<property>
    <name>dfs.permissions</name>
    <value>false</value>
</property>

5.2 Edit hdfs-site.xml

# vim conf/hdfs-site.xml

# Add the following inside the 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>2</value>
</property>

5.3 Edit mapred-site.xml

# vim conf/mapred-site.xml

# Add the following inside the configuration tag
<property>
        <name>mapred.job.tracker</name>
	<value>localhost:9001</value>
</property>

5.4 Edit hadoop-env.sh

# vim conf/hadoop-env.sh

export JAVA_HOME=/opt/jdk1.7.0_17
export HADOOP_OPTS=-Djava.net.preferIPv4Stack=true

Set JAVA_HOME path as per your system configuration for java.

Next to format Name Node

# su - hadoop
$ cd /opt/hadoop/hadoop
$ bin/hadoop namenode -format

13/06/02 22:53:48 INFO namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG:   host = srv1.tecadmin.net/192.168.1.90
STARTUP_MSG:   args = [-format]
STARTUP_MSG:   version = 1.2.1
STARTUP_MSG:   build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2 -r 1479473; compiled by 'hortonfo' on Mon May  6 06:59:37 UTC 2013
STARTUP_MSG:   java = 1.7.0_17
************************************************************/
13/06/02 22:53:48 INFO util.GSet: Computing capacity for map BlocksMap
13/06/02 22:53:48 INFO util.GSet: VM type       = 32-bit
13/06/02 22:53:48 INFO util.GSet: 2.0% max memory = 1013645312
13/06/02 22:53:48 INFO util.GSet: capacity      = 2^22 = 4194304 entries
13/06/02 22:53:48 INFO util.GSet: recommended=4194304, actual=4194304
13/06/02 22:53:49 INFO namenode.FSNamesystem: fsOwner=hadoop
13/06/02 22:53:49 INFO namenode.FSNamesystem: supergroup=supergroup
13/06/02 22:53:49 INFO namenode.FSNamesystem: isPermissionEnabled=true
13/06/02 22:53:49 INFO namenode.FSNamesystem: dfs.block.invalidate.limit=100
13/06/02 22:53:49 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
13/06/02 22:53:49 INFO namenode.FSEditLog: dfs.namenode.edits.toleration.length = 0
13/06/02 22:53:49 INFO namenode.NameNode: Caching file names occuring more than 10 times
13/06/02 22:53:49 INFO common.Storage: Image file of size 112 saved in 0 seconds.
13/06/02 22:53:49 INFO namenode.FSEditLog: closing edit log: position=4, editlog=/opt/hadoop/hadoop/dfs/name/current/edits
13/06/02 22:53:49 INFO namenode.FSEditLog: close success: truncate to 4, editlog=/opt/hadoop/hadoop/dfs/name/current/edits
13/06/02 22:53:49 INFO common.Storage: Storage directory /opt/hadoop/hadoop/dfs/name has been successfully formatted.
13/06/02 22:53:49 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at srv1.tecadmin.net/192.168.1.90
************************************************************/

Step 6: Start Hadoop Services

Use the following command to start all hadoop services.

$ bin/start-all.sh

[sample output]

starting namenode, logging to /opt/hadoop/hadoop/libexec/../logs/hadoop-hadoop-namenode-ns1.tecadmin.net.out
localhost: starting datanode, logging to /opt/hadoop/hadoop/libexec/../logs/hadoop-hadoop-datanode-ns1.tecadmin.net.out
localhost: starting secondarynamenode, logging to /opt/hadoop/hadoop/libexec/../logs/hadoop-hadoop-secondarynamenode-ns1  .tecadmin.net.out
starting jobtracker, logging to /opt/hadoop/hadoop/libexec/../logs/hadoop-hadoop-jobtracker-ns1.tecadmin.net.out
localhost: starting tasktracker, logging to /opt/hadoop/hadoop/libexec/../logs/hadoop-hadoop-tasktracker-ns1.tecadmin.ne  t.out

Step 7: Test and Access Hadoop Services

Use ‘jps‘ command to check if all services are started well.

$ jps
or
$ $JAVA_HOME/bin/jps

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

Web Access URLs for Services

  http://srv1.tecadmin.net:50030/   for the Jobtracker
  http://srv1.tecadmin.net:50070/   for the Namenode
  http://srv1.tecadmin.net:50060/   for the Tasktracker

Hadoop JobTracker: 

Hadoop Namenode: 

Hadoop TaskTracker: 

Step 8: Stop Hadoop Services

If you do no need anymore hadoop. Stop all hadoop services using following command.

# bin/stop-all.sh