single node hadoop cluster setup on cent os-gopal (1)

8/10/2019 Single Node Hadoop Cluster Setup on Cent Os-gopal (1)

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SINGLE NODE HADOOP CLUSTER SETUP ON CENT OS

- By Gopal Krishna

----------------------------------------------------------

STEP 1: Download VMWare Player or VMWare Workstation

You may download the VMware player from below location.

https://my.vmware.com/web/vmware/free#desktop_end_user_computing/vmware_play

er/5_0

STEP 2: Download CentOS iso DVD version 6.3, which is stable version

For 64 bit windows use below URL

http://mirrors.hns.net.in/centos/6.3/isos/x86_64/

For 32 bit windows, use the below URL

http://wiki.centos.org/Download

STEP 3: Run the VMware player and click on Create New Virtual Machine.

Browse to the isodownloaded in previous step.

CentOS will be installed on local system. You will be asked to enter password

for the root user, enter your root password and do remember it.

After installation is over, you please click on Install to diskicon on your CentOS

Desktop.

Once the installation is over, you please shutdown the machine and log in as root

user.

STEP 4: Installation of VMWare Tools


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After installing the VMWare player, you can install VMware tools so that you can share data from

host system to guest system. You can see full system view only if you install VMware tools. Below

are the steps for installing the VMWare tools

Go to VM Menu Item and select Install VMWare Tools shown in the below screenshot:

Go to desktop

cd ~/Desktop

you can untar the tar file

tar -xzf VMwareTools*.tar.gz

cd ~/Desktop/vmware-tools-distrib

Install the vmware tools

./vmware-install.pl

After the above command, if you ask you for some values and the defaults are good

enough. You have to press enter 10-12 times

Enable sharing between the host OS and guest OS as follows:

Go to Virtual Machine Virtual Machine Settings Options Shared Foldersandsee

ifthe share is enabled or not. If sharing is enabled, you can add a new sharelocation


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STEP 5: Installation of JAVA

Hadoop needs to have Java installed on your CentOS but CentOS does not come

with

Oracle Java because of licensing issues. So, please use the below commands

to install java.

Download the latest java from blow location. Click on the link Click on

JDK Download button and select the Accept license agreement ratio

button.

http://www.oracle.com/technetwork/java/javase/downloads/index.html

[root@localhost ~]#rpm -Uvh /root/Downloads/jdk-7u15-linux-x64.rpm

[root@localhost ~]#alternatives --install /usr/bin/java java/usr/java/latest/jre/bin/java 20000

[root@localhost ~]#export JAVA_HOME="/usr/java/latest"


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Confirm the java path by running[root@localhost ~]#javac version

[root@localhost ~]#javac -versionjavac 1.7.0_15

[root@localhost ~]#

Confirm the java version by running

[root@localhost ~]#java -versionjava version "1.7.0_15"

Java(TM) SE Runtime Environment (build 1.7.0_15-b03)Java HotSpot(TM) 64-Bit Server VM (build 23.7-b01, mixed mode)[root@localhost ~]#

If you face any issues while installing the JDK, please check theJDK version you have download and the one you are using in the

command.

If it shows some errors related to missing packages, just ignore them

STEP 6: Confirm your machine name

When you create a new CentOS machine, the default host name is

localhost.localdomain. Check your hostname by giving the following command.

[root@localhost ~]#hostname

You should get localhost.localdomain as output of above command.

STEP 7: Adding a dedicated Hadoop system user

We will use a dedicated Hadoop user account for running Hadoop. While thats notrequired it is recommended because it helps to separate the Hadoop installationfrom other software applications and user accounts running on the same machine

(think: security, permissions, backups, etc).

[root@localhost ~]#groupadd hadoop[root@localhost ~]#useradd hduser -g

hadoop[root@localhost ~]#passwd hduser

It asks for new password, enter again for confirmation and do remember

yourpassword.

Add the hduser to sudoers list so that hduser can do admin

tasks. Step 1.visudo


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Step 2: Add a line under ##Allow root to run commands anywhere in theformat.hduser ALL=(ALL) ALL

This will add the user hduser and the group hadoop to your local machine.

Exit from root user and login as hduser to proceed further, typethe following for switching from root to hduser

[root@localhost ~]#s u h d u s e r

STEP 8: Configuring SSH

Hadoop requires SSH access to manage its nodes, i.e. remote machines plus your

local machine if you want to use Hadoop on it (which is what we want to do in this

short tutorial). For our single-node setup of Hadoop, we therefore need toconfigure SSH access to localhost for the hduser user we created in the previous

section.

I assume that you have SSH up and running on your machine and configured it to

allow SSH public key authentication.

Install ssh server on your computer

[hduser@localhost ~]$sudo yum install openssh-server

NOTE:For the above step, INTERNET connection should be enabled

[hduser@localhost ~]$ssh-keygen

Generating public/private rsa key pair. Enter file in which to save the key(/home/hduser/.ssh/id_rsa):

Created directory '/home/hduser/.ssh'.

Your identification has been saved in /home/hduser/.ssh/id_rsa.Your public key has been saved in /home/hduser/.ssh/id_rsa.pub.The key fingerprint is:

9b:82:ea:58:b4:e0:35:d7:ff:19:66:a6:ef:ae:0e:d2hduser@localhostThe key's randomart image is:

+--[ RSA 2048]----+

| |

| |

| . |

| * |

| = S oo |

| . ooOoo. |

| .*E . |

| ..o= |

| ++. |

+-----------------+


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[hduser@localhost ~]$

The final step is to test the SSH setup by connecting to your local machine with the

hduser user. The step is also needed to save your local machines host keyfingerprint to the hduser users known_hosts file. If you have any special SSHconfiguration for your local machine like a non-standard SSH port, you can define

host-specific SSH options in $HOME/.ssh/config (see man ssh_config for moreinformation).

#now copy the public key to the authorized_keys file, so that ssh should not require

passwords every time

[hduser@localhost ~]$c a t ~ / . s s h / i d _ r s a . p u b > > ~ / . s s h / a u t h o r i z e d _ k e y s

#Change permissions of the authorized_keys fie to have all permissions for hduser

[hduser@localhost ~]$chmod 700 ~/.ssh/authorized_keys

If ssh is not running, then run it by giving the below command

[hduser@localhost ~]$sudo service sshd startIf ssh is not running, then run it by giving the below command

Run the below command to have the sshd running even after system reboot.

hduser@localhost:~$sudo chkconfig sshd on

Stop the firewalls if enabled by following commands

[hduser@localhost ~]$sudo service iptables stop

Run the below command to have the iptables stopped even after system reboot.

hduser@localhost:~$sudo chkconfig iptables off


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Test the ssh connectivity by doing the following

[hduser@localhost ~]$ssh localhost

We should be able to ssh localhost without password prompt. If it asks forpassword while connecting to localhost, there is something went wrong andyou need to fix it before proceeding further.

Without having the password less SSH working properly, the hadoop cluster will notwork, so there is no point in going further if password less SSH is not working. If youface any issues with SSH, consult Google University, where copious help available.

The authenticity of host 'localhost (::1)' can't be established.RSA key fingerprint is d7:87:25:47:ae:02:00:eb:1d:75:4f:bb:44:f9:36:26.

Are you sure you want to continue connecting (yes/no)?yes

Warning: Permanently added 'localhost' (RSA) to the list of known hosts.Linux ubuntu 2.6.32-22-generic #33-Ubuntu SMP Wed Apr 28 13:27:30 UTC 2010

i686 GNU/Linux

Ubuntu 10.04 LTS[...snipp...]

Next sections will describe how to setup and run hadoop

STEP 9: Download Hadoop

For this tutorial, I am using Hadoop version 1.0.4, but it should work with any other

version.

Got to the URL http://archive.apache.org/dist/hadoop/core/andclick on hadoop-1.0.4/ and then select hadoop-1.0.4.tar.gz. The file will be saved to/home/hduser/Downloads if you choose defaults. Now perform the following steps toinstall Hadoop on your CentOS.

Copy your downloaded file from Downloads folder to /usr/local folder

$sudo cp /home/hduser/Downloads/hadoop-1.0.4.tar.gz/usr/local

$cd /usr/local$sudo tar -xzf hadoop-1.0.4.tar.gz

$sudo chown -R hduser:hadoop hadoop-1.0.4$sudo ln -s hadoop-1.0.4 hadoop

$sudo chown -R hduser:hadoop hadoop

STEP 10: Add Java location to Hadoop so that it can recognize Java

Add the following to /usr/local/hadoop/conf/hadoop-env.sh. Type the below

command to enter contents into the hadoop-env.sh file


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nano /usr/local/hadoop/conf/hadoop-env.sh

export HADOOP_OPTS=-Djava.net.preferIPv4Stack=trueexport HADOOP_HOME_WARN_SUPPRESS="TRUE" export

JAVA_HOME=/usr/java/default

STEP 11: Update $HOME/.bashrc

Add the following lines to the end of the $HOME/.bashrc file of user hduser. If you

use a shell other than bash, you should of course update its appropriateconfiguration files instead of .bashrc.

Give the below commands to edit .bashrc file and paste the below commands andsave the file.

nano ~/.bashrc

# Set Hadoop-related environment variablesexport HADOOP_HOME=/usr/local/hadoop

# Set JAVA_HOME (we will also configure JAVA_HOME directly for Hadoop later on)

export JAVA_HOME=/usr/java/default

# Some convenient aliases and functions for running Hadoop-related commandsunaliasfs&> /dev/nullaliasfs="hadoop fs"unaliashls&> /dev/null

aliashls="fs -ls"

# If you have LZO compression enabled in your Hadoop cluster and# compress job outputs with LZOP (not covered in this tutorial):

# Conveniently inspect an LZOP compressed file from the command

# line; run via:## $ lzohead /hdfs/path/to/lzop/compressed/file.lzo

## Requires installed 'lzop' command.#

lzohead () {hadoopfs -cat $1 | lzop -dc | head -1000 | less

}

# Add Hadoop bin/ directory to PATHexport PATH=$PATH:$HADOOP_HOME/bin:$PATH:$JAVA_HOME/bin

You need to close the terminal and open a new terminal to have the bash changes

into effect.


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STEP 12: Create a temporary directory which will be used as base location for DFS.

Now we create the directory and set the required ownerships and permissions:

$ sudo mkdir -p /app/hadoop/tmp$ sudo chown -R hduser:hadoop /app/hadoop/tmp$ sudo chmod -R 750 /app/

$ sudo chmod -R 750 /app/hadoop$ sudo chmod -R 750 /app/hadoop/tmp

If you forget to set the required ownerships and permissions, you will see ajava.io.IOException when you try to format the name node in the next section).

STEP 13: core-site.xml file updating

Add the following snippets between the ... tagsin/usr/local/hadoop/conf/core-site.xml:

Add the following snippets between the ... tags in

/usr/local/hadoop/conf/core-site.xml:

nano /usr/local/hadoop/conf/core-site.xml

hadoop.tmp.dir

/app/hadoop/tmp

A base for other temporary directories.

fs.default.namehdfs://localhost:54310

The name of the default file system. A URI whose

scheme and authority determine the FileSystem implementation. Theuri's scheme determines the config property (fs.SCHEME.impl) naming

theFileSystem implementation class. The uri's authority is used todetermine the host, port, etc. for a filesystem.

STEP 14: mapred-site.xml file updating

Add the following to /usr/local/hadoop/conf/mapred-site.xml between ...


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nano /usr/local/hadoop/conf/mapred-site.xml

mapred.job.trackerlocalhost:54311

The host and port that the MapReduce jobtracker runs at. If "local", then jobs are run in-process as a

single map

and reduce task.

STEP 15: hdfs-site.xml file updating

Add the following to /usr/local/hadoop/conf/hdfs-site.xml between

...

nano /usr/local/hadoop/conf/hdfs-site.xml

dfs.replication

1Default block replication.The actual number of replications can be specified when the file is created.The default is used if replication is not specified in create time.

STEP 16: Format the Name Node

Format hdfs cluster with below command

[hduser@localhost ~]$hadoop namenode -format

If the format is not working, double check your entries in .bashrc file. The .bashrc

updating come into force only if you have opened a new terminal


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STEP 17: Starting single-node cluster

Congratulations, your Hadoop single node cluster is ready to use. Test your cluster by

running the following commands.

[hduser@localhost ~]$start-all.sh

If you get any SSH related error like connection refused etc, ensure that your ssh

service is running by checking with below command and run it if needed.

[hduser@localhost ~]$sudo service sshd status

A command line utility to check whether all the hadoop demons are running or not is:

jps

Give the jps at command prompt and you should see something like below.[hduser@localhost ~]$jps

9168 Jps

9127 TaskTracker

8824 DataNode

8714 NameNode

8935 SecondaryNameNode

9017 JobTracker

Check if the hadoop is accessible through browser by hitting the below URLs

For mapreduce - http://localhost:50030

For hdfs -http://localhost:50070

single node hadoop cluster setup on cent os-gopal (1)

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