First of all, THESE ARE IMPORTANT FOR INDRODUCTION

*Ubuntu server 14.04
*VM in VirtualBox with 1GB RAM
*SWAP SPACE :   SELECT  more than 2 GB

Up-to-date system.

Moreover, it is advisable not to run Hadoop services through a general-purpose user, so the next step consists in adding a group hadoop and a user hadoop-user belonging to that group

Installing Java
The mentioned tutorials suggest a potentially unsafe procedure in order to install the jdk through apt-get,

Finally, a couple of environment variables should be set up so that the java executables are in $PATH and hadoop knows where java has been installed: this is easily accomplished adding

at the end of /etc/profile  <<< We need to edit that to set automatically JAVA PATH 

Setup SSH

All communications with Hadoop are encrypted via SSH, thus the corresponding server should be installed:

 

and the hadoop-user must be associated to a key pair and subsequently granting its access to the local machine:

 

Now hadoop-user should be able to access via ssh to localhost without ( WE SET THE PASS = “null”)providing a password:

 

Disable IPV6

Hadoop and IPV6 do not agree on the meaning of 0.0.0.0 address,

LOOK AT : ??>>>>> /etc/sysctl.conf

REBOOT SYSTEM

CONTROL

Hadoop

Download and install Hadoop

Download hadoop-2.4.0.tar.gz, unpack it and move the results in /usr/local, adding a symlink using the more friendly name hadoop and changing ownership of the directory contents to the hadoop-user user:

Setup the dedicated user environment
Switch to the hadoop-user user and add the following lines at the end of ~/.bashrc:

To have the new environment variables in place,

1- reload .bashrc   through “source .bashrc"

2- then open /usr/local/hadoop/etc/hadoop/hadoop-env.sh ,

3- uncomment the line setting JAVA_HOME and set its value to the jdk directory:

Configure Hadoop

Before being able to actually use the hadoop file system it is necessary to modify some configuration files inside /usr/local/hadoop/etc/hadoop
All such files follow the an XML format, and the updates should concern the top-level node configuration
(likely empty after the hadoop installation). Specifically:

• in yarn-site.xml :
  
  yarn.nodemanager.aux-services mapreduce_shuffle yarn.nodemanager.aux-services.mapreduce.shuffle.class org.apache.hadoop.mapred.ShuffleHandler

  1 2 3 4 5 6

  yarn.nodemanager.aux-services     mapreduce_shuffle           yarn.nodemanager.aux-services.mapreduce.shuffle.class     org.apache.hadoop.mapred.ShuffleHandler

• look in core-site.xml:
  
  fs.default.name hdfs://localhost:9000

  1 2	fs.default.name     hdfs://localhost:9000

• look in mapred-site.xml
  
  mapreduce.framework.name yarn

  1 2	mapreduce.framework.name     yarn

• nano hdfs-site.xml:
  
  dfs.replication 1 dfs.namenode.name.dir file:/usr/local/hadoop/yarn_data/hdfs/namenode dfs.datanode.data.dir file:/usr/local/hadoop/yarn_data/hdfs/datanode

  1 2 3 4 5 6 7 8 9 10

  dfs.replication     1           dfs.namenode.name.dir     file:/usr/local/hadoop/yarn_data/hdfs/namenode           dfs.datanode.data.dir     file:/usr/local/hadoop/yarn_data/hdfs/datanode

Run these commands.

Formatting the distributed file system

USER should be  hadoop user 

Find the  these 2 file  and  run 

start-dfs.sh

start-yarn.sh