Tuesday, January 4, 2011

Installation of hadoop in the cluster - A complete step by step tutorial




Hadoop Cluster Setup:

Hadoop is a fault-tolerant distributed system for data storage which is highly scalable.
Hadoop has two important parts:-

1. Hadoop Distributed File System(HDFS):-A distributed file system that provides high throughput access to application data.

2. MapReduce:-A software framework for distributed processing of large data sets on compute clusters.

In this tutorial, I will describe how to setup and run Hadoop cluster. We will build Hadoop cluster using three Ubuntu machine in this tutorial.

Following are the capacities in which nodes may act in our cluster:-

1. NameNode:-Manages the namespace, file system metadata, and access control. There is exactly one NameNode in each cluster.

2. SecondaryNameNode:-Downloads periodic checkpoints from the nameNode for fault-tolerance. There is exactly one SecondaryNameNode in each cluster.

3. JobTracker: - Hands out tasks to the slave nodes. There is exactly one JobTracker in each cluster.

4. DataNode: -Holds file system data. Each data node manages its own locally-attached storage (i.e., the node's hard disk) and stores a copy of some or all blocks in the file system. There are one or more DataNodes in each cluster.

5. TaskTracker: - Slaves that carry out map and reduce tasks. There are one or more TaskTrackers in each cluster.

In our case, one machine in the cluster is designated as namenode, Secondarynamenode and jobTracker.This is the master. The rest of machine in the cluster act as both Datanode and TaskTracker. They are slaves.

Below diagram show, how the Hadoop cluster will look after Installation:-

Fig: After Installation, Hadoop cluster will look like.

Installation, configuring and running of hadoop cluster is done in three steps:
1. Installing and configuring hadoop namenode.
2. Installing and configuring hadoop datanodes.
3. Start and stop hadoop cluster.

INSTALLING AND CONFIGURING HADOOP NAMENODE

1. Download hadoop-0.20.2.tar.gz from http://www.apache.org/dyn/closer.cgi/hadoop/core/ and extract to some path in your computer. Now I am calling hadoop installation root as $HADOOP_INSTALL_DIR.

2. Edit the file /etc/hosts on the namenode machine and add the following lines.
           
192.168.41.53    hadoop-namenode
            192.168.41.87    hadoop-datanode1
            192.168.41.67    hadoop-datanode2

Note: Run the command “ping hadoop-namenode”. This command is run to check whether the namenode machine ip is being resolved to actual ip not localhost ip.

3. We have needed to configure password less login from namenode to all datanode machines.
            2.1. Execute the following commands on namenode machine.
                        $ssh-keygen -t rsa
                        $scp .ssh/id_rsa.pub ilab@192.168.41.87:~ilab/.ssh/authorized_keys
                        $scp .ssh/id_rsa.pub ilab@192.168.41.67:~ilab/.ssh/authorized_keys

4. Open the file $HADOOP_INSTALL_DIR/conf/hadoop-env.sh and set the $JAVA_HOME.
export JAVA_HOME=/path/to/javaeg : export JAVA_HOME=/user/lib/jvm/java-6-sun
Note:  If you are using open jdk , then give the path of that open jdk.

5. Go to $HADOOP_INSTALL_DIR and create new directory hadoop-datastore. This directory is creating to store metadata information.

6. Open the file $HADOOP_INSTALL_DIR/conf/core-site.xml and add the following properties. This file is edit to configure the namenode to store information like port number and metadata directories. Add the properties in the format below:
            <!-- Defines the namenode and port number -->
            <property>
                              <name>fs.default.name</name>
                              <value>hdfs://hadoop-namenode:9000</value>
                              <description>This is the namenode uri</description>
            </property>
            <property>
      <name>hadoop.tmp.dir</name>
      <value>$HADOOP_INSTALL_DIR/hadoop-0.20.2/hadoop-datastore
      </value>
      <description>A base for other temporary directories.</description>
            </property>

7. Open the file $HADOOP_INSTALL_DIR/conf/hdfs-site.xml and add the following properties. This file is edit to configure the replication factor of the hadoop setup. Add the properties in the format below:
           
<property>
                       <name>dfs.replication</name>
                       <value>2</value>
<description>Default 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.
                       </description>
            </property>

8. Open the file $HADOOP_INSTALL_DIR/conf/mapred-site.xml and add the following properties. This file is edit to configure the host and port of the MapReduce job tracker in thenamenode of the hadoop setup. Add the properties in the format below:
            <property>
                        <name>mapred.job.tracker</name>
                        <value>hadoop-namenode:9001</value>
                        <description>The host and port that the MapReduce job tracker runs
                        at.  If "local", then jobs are run in-process as a single map and reduce 
                        task.
                        </description>
            </property>

9. Open the file $HADOOP_INSTALL_DIR/conf/masters and add the machine names where a secondary namenodes will run. This file is edit to configure the Hadoop Secondary Namenode
hadoop-namenode.
           
Note: In my case, both primary namenode and Secondary namenode are running on same machine. So, I have added hadoop-namenode in $HADOOP_INSTALL_DIR/conf/masters file.

10. Open the file $HADOOP_INSTALL_DIR/conf/slaves and add all the datanodes machine names:-
            hadoop-namenode     
/* in case you want the namenode to also store data(i.e namenode also behave like a datanode) this can be  mentioned in the slaves file.*/
            hadoop-datanode1
            hadoop-datanode2

INSTALLING AND CONFIGURING HADOOP DATANODE


1. Download hadoop-0.20.2.tar.gz from http://www.apache.org/dyn/closer.cgi/hadoop/core/ and extract to some path in your computer. Now I am calling hadoop installation root as $HADOOP_INSTALL_DIR.

2. Edit the file /etc/hosts on the datanode machine and add the following lines.
           
192.168.41.53    hadoop-namenode
            192.168.41.87    hadoop-datanode1
            192.168.41.67    hadoop-datanode2

Note: Run the command “ping hadoop-namenode”. This command is run to check whether   the namenode machine ip is being resolved to actual ip not localhost ip.

3. We have needed to configure password less login from all datanode machines to namenode machine.
            3.1. Execute the following commands on datanode machine.
                        $ssh-keygen -t rsa
                        $scp .ssh/id_rsa.pub ilab@192.168.41.53:~ilab/.ssh/authorized_keys2

4. Open the file $HADOOP_INSTALL_DIR/conf/hadoop-env.sh and set the $JAVA_HOME.
export JAVA_HOME=/path/to/java
eg : export JAVA_HOME=/user/lib/jvm/java-6-sun

Note:  If you are using open jdk , then give the path of that open jdk.

5. Go to $HADOOP_INSTALL_DIR and create new directory hadoop-datastore. This directory is creating to store metadata information.

6. Open the file $HADOOP_INSTALL_DIR/conf/core-site.xml and add the following properties. This file is edit to configure the datanode to determine the host, port, etc. for a filesystem. Add the properties in the format below:
           <!-- The uri's authority is used to determine the host, port, etc. for a filesystem. -->
            <property>
                        <name>fs.default.name</name>
                        <value>hdfs://hadoop-namenode:9000</value>
                        <description>This is the namenode uri</description>
            </property>
            <property>
                       <name>hadoop.tmp.dir</name>
                       <value>$HADOOP_INSTALL_DIR/hadoop-0.20.2/hadoop-datastore
                       </value>
                       <description>A base for other temporary directories.</description>
            </property>

7. Open the file $HADOOP_INSTALL_DIR/conf/hdfs-site.xml and add the following properties. This file is edit to configure the replication factor of the hadoop setup. Add the properties in the format below:
            <property>
                                    <name>dfs.replication</name>
                                    <value>2</value>
                                    <description>Default 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.
                                    </description>
            </property>

8. Open the file $HADOOP_INSTALL_DIR/conf/mapred-site.xml and add the following properties. This file is edit to identify the host and port at which MapReduce job tracker runs in the namenode of the hadoop setup. Add the properties in the format below
            <property>
                        <name>mapred.job.tracker</name>
                        <value>hadoop-namenode:9001</value>
                        <description>The host and port that the MapReduce job tracker runs
                         at.  If "local", then jobs are run in-process as a single map and reduce 
                         task.
                        </description>
</property>

Note:-Step 9 and 10 are not mandatory.

9. Open $HADOOP_INSTALL_DIR/conf/masters and add the machine names where a secondary namenodes will run.
            hadoop-namenode

Note: In my case, both primary namenode and Secondary namenode are running on same machine. So, I have added hadoop-namenode in $HADOOP_INSTALL_DIR/conf/masters file.

10. open $HADOOP_INSTALL_DIR/conf/slaves and add all the datanodes machine names
hadoop-namenode                  /* In case you want the namenode to also store data(i.e namenode also behave like datanode) this can be mentioned in the slaves file.*/
            hadoop-datanode1
            hadoop-datanode2

  
Note:-
Above steps is  required on all the datanode in the hadoop cluster.

START AND STOP HADOOP CLUSTER

1. Formatting the namenode:-
Before we start our new Hadoop cluster, we have to format Hadoop’s distributed filesystem (HDFS) for the namenode. We have needed to do this the first time when we start our Hadoop cluster. Do not format a running Hadoop namenode, this will cause all your data in the HDFS filesytem to be lost.
Execute the following command on namenode machine to format the file system.
$HADOOP_INSTALL_DIR/bin/hadoop namenode -format

2. Starting the Hadoop cluster:-
            Starting the cluster is done in two steps.
           
2.1 Start HDFS daemons:-
           
Execute the following command on namenode machine to start HDFS daemons.
            $HADOOP_INSTALL_DIR/bin/start-dfs.sh
            Note:-
            At this point, the following Java processes should run on namenode
            machine. 
                        ilab@hadoop-namenode:$jps // (the process IDs don’t matter of course.)
                        14799 NameNode
                        15314 Jps
                        14977 SecondaryNameNode
                        ilab@hadoop-namenode:$
            and the following java procsses should run on datanode machine.
                        ilab@hadoop-datanode1:$jps //(the process IDs don’t matter of course.)
                        15183 DataNode
                        15616 Jps
                        ilab@hadoop-datanode1:$

            2.2 Start MapReduce daemons:-
            Execute the following command on the machine you want the jobtracker to run 
            on.
$HADOOP_INSTALL_DIR/bin/start-mapred.sh     
//In our case, we will run bin/start-mapred.sh on namenode machine:
           Note:-
           At this point, the following Java processes should run on namenode machine.       
                        ilab@hadoop-namenode:$jps // (the process IDs don’t matter of course.)
                        14799 NameNode
                        15314 Jps
                        14977 SecondaryNameNode
                        15596 JobTracker                 
                        ilab@hadoop-namenode:$

            and the following java procsses should run on datanode machine.
                        ilab@hadoop-datanode1:$jps //(the process IDs don’t matter of course.)
                        15183 DataNode
                        15616 Jps
                        15897 TaskTracker               
                        ilab@hadoop-datanode1:$

3. Stopping the Hadoop cluster:-
            Like starting the cluster, stopping it is done in two steps.
3.1 Stop MapReduce daemons:-
Run the command /bin/stop-mapred.sh on the jobtracker machine. In our case, we will run bin/stop-mapred.sh on namenode:
            3.2 Stop HDFS daemons:-
                        Run the command /bin/stop-dfs.sh on the namenode machine.





40 comments:

Nishu Tayal said...

Nice job...!!!!

m00m said...

hi! thanks for this tutorial. Can i have 2 datanodes in the same machine? how can i do that?

krishrocking4 said...

nice work dude...can u add some more docs about hive & hbase integration.

Itsmyview said...

Hi very nice post. i am able to ping from one machine to other, but when i ran bin/star-dfs.sh i am getting following error. please help.

hduser@vamshikrishna-desktop:/usr/local/hadoop-0.20.2$ bin/start-dfs.sh
starting namenode, logging to /usr/local/hadoop-0.20.2/bin/../logs/hadoop-hduser-namenode-vamshikrishna-desktop.out
The authenticity of host 'hadoop-namenode (10.0.1.54)' can't be established.
RSA key fingerprint is 44:ff:09:b0:5c:e5:19:17:b7:cb:4d:d0:ee:19:7f:41.
Are you sure you want to continue connecting (yes/no)? The authenticity of host 'hadoop-datanode1 (10.0.1.56)' can't be established.
RSA key fingerprint is 66:c4:46:00:7f:64:11:f9:ea:4f:51:86:b3:0a:07:bd.
Are you sure you want to continue connecting (yes/no)?

Itsmyview said...

Sorry, its not error, but its repeatedly asking me
'yes' or 'no' though i entered my response as 'yes'.
Even i tried with 'no' , then also same thing is happening. what is the reason and how can i solve it.

Thank you

Ankit Jain said...

are you able to ssh from master(hadoop-namenode) machine to slave (hadoop-datanode) machine??

K Som Shekhar Sharma said...

Hi,
Have you automated the installation process using Puppet script? If you have done it would be great if you can share the same.

K Som Shekhar Sharma said...

@itsmyview:
The nodes in the cluster communicate with each other via SSH. The NameNode should be able to SSH into the data nodes in a password-less manner. For this, an ssh rsa key has to be generated on the NameNode.
ssh-keygen -t rsa -P “”
This command produces two files in the ‘.ssh’ directory inside hadoop user’s home directory.
.ssh/id_rsa This file holds the private key for the Hadoop user at Name Node
.ssh/id_rsa.pub This file holds the public key for the Hadoop user.
Now this public key should be added in the Authorized key list of all the Data Nodes. Thus, whenever NameNode tries to remote login into any of the datanodes, the datanode will check the NameNode’s identity in its own Authorized keys file, recognize the NameNode as an authorized guest and allow entry password-lessly.
Caution:
SSH may not work if the permissions for the .ssh directory are not set correctly. Permissions should not be too open neither too restrictive. The contents should be writable only by the owner. Otherwise it is assumed to be a security hole by the SSH server, and access is denied.
you can set the permission as 600 and it will work fine.

thejranjan said...

Hi, one of the best documentation i found for beginners who want to setup Hadoop Cluster. Thanks for sharing this, this post was very much useful.

My Humble request is to align the post so that it is easy to read.

Thank you Ankit

Ankit Jain said...

Thanks thejranjan .........

Arun said...

Nice post !

But it repeatedly asks for hadoop-namenode password when starting daemons like this :
hduser@arun-desktop:/usr/local/hadoop-0.20.2$ bin/start-all.sh
starting namenode, logging to /usr/local/hadoop-0.20.2/bin/../logs/hadoop-hduser-namenode-arun-desktop.out
hduser@hadoop-namenode's password: hadoop-datanode1: starting datanode, logging to /usr/local/hadoop-0.20.2/bin/../logs/hadoop-hduser-datanode-rkn-desktop.out

hadoop-namenode: starting datanode, logging to /usr/local/hadoop-0.20.2/bin/../logs/hadoop-hduser-datanode-arun-desktop.out
shduser@hadoop-namenode's password:
hadoop-namenode: starting secondarynamenode, logging to /usr/local/hadoop-0.20.2/bin/../logs/hadoop-hduser-secondarynamenode-arun-desktop.out
starting jobtracker, logging to /usr/local/hadoop-0.20.2/bin/../logs/hadoop-hduser-jobtracker-arun-desktop.out
sahduser@hadoop-namenode's password: hadoop-datanode1: starting tasktracker, logging to /usr/local/hadoop-0.20.2/bin/../logs/hadoop-hduser-tasktracker-rkn-desktop.out

hadoop-namenode: starting tasktracker, logging to /usr/local/hadoop-0.20.2/bin/../logs/hadoop-hduser-tasktracker-arun-desktop.out

Any idea ?

Arun

Ankit Jain said...

Please set passwordless ssh.
run the following commands.
1. $ssh-keygen -t rsa
and press enter
2. $cp ~/.ssh/rsa.pub ~/.ssh/authorized_keys

3. $scp ~/.ssh/rsa.pub ${USER}@hadoop-datanode1:~/.ssh/authorized_keys

Run step 3rd for each slaves or datanode.
Ex:
$scp ~/.ssh/rsa.pub ${USER}@hadoop-datanode2:~/.ssh/authorized_keys

Kumar said...

hello! thanks for this tutorial
nice doc... this was very help full, can u add some more docs about hive & sqoop integration

Ankit Jain said...

Hi Kumar,

http://ankitasblogger.blogspot.in/2012/01/sqoop-export-and-import-commands.html post contains the sqooop import and export commands.

Kumar said...

Hi Ankit,
I have setup the Hadoop cluster of 5 nodes , is there any way how i can choose to write to a particular datanode in the cluster. when we do the DFS PUT operation i must be able to specify which datanodes to store the data. Also can we have a control on the block size of data that is distributed i.e., to mention the block size at the run time while loading the data into the Hadoop.

Ankit Jain said...

Hi,

I think we can't choose to write data into particular datanode. Yes, we can specify the block size at run time. Please try to explore the Hadoop api.

Thanks,
Ankit Jain

najeeb said...

Hi Ankit
I config one cluster using the tutorial. But i cant format my name node. its giving the following error.
Cant remove the current directory.
Any solution.?

Ankit Jain said...

Hi Najeeb,

Please share the error message. It helps me to identify the root cause of your problem.

~ Ankit

najeeb said...

hadoop@debian:~/Desktop/hadoop-0.20.2/bin$ ./hadoop namenode -format
12/05/22 05:00:41 INFO namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = debian/127.0.1.1
STARTUP_MSG: args = [-format]
STARTUP_MSG: version = Unknown
STARTUP_MSG: build = Unknown -r Unknown; compiled by 'Unknown' on Unknown
************************************************************/
Re-format filesystem in /tmp/hadoop/cluster/dfs/name ? (Y or N) Y
12/05/22 05:00:45 INFO namenode.FSNamesystem: fsOwner=hadoop,hadoop,cdrom,floppy,audio,dip,video,plugdev,netdev,bluetooth,scanner
12/05/22 05:00:45 INFO namenode.FSNamesystem: supergroup=supergroup
12/05/22 05:00:45 INFO namenode.FSNamesystem: isPermissionEnabled=true
12/05/22 05:00:45 ERROR namenode.NameNode: java.lang.IllegalStateException
at java.nio.charset.CharsetEncoder.encode(libgcj.so.10)
at org.apache.hadoop.io.Text.encode(Text.java:388)
at org.apache.hadoop.io.Text.encode(Text.java:369)
at org.apache.hadoop.io.Text.writeString(Text.java:409)
at org.apache.hadoop.fs.permission.PermissionStatus.write(PermissionStatus.java:110)
at org.apache.hadoop.hdfs.server.namenode.FSImage.saveINode2Image(FSImage.java:1146)
at org.apache.hadoop.hdfs.server.namenode.FSImage.saveFSImage(FSImage.java:1026)
at org.apache.hadoop.hdfs.server.namenode.FSImage.format(FSImage.java:1091)
at org.apache.hadoop.hdfs.server.namenode.FSImage.format(FSImage.java:1110)
at org.apache.hadoop.hdfs.server.namenode.NameNode.format(NameNode.java:856)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:948)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:965)

12/05/22 05:00:45 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at debian/127.0.1.1
************************************************************/

najeeb said...

# i am adding my conf files too..
#core-site.xml







hadoop.tmp.dir
/tmp/hadoop/cluster/
A base for other temp directories


fs.default.name
hdfs://127.0.0.1:9000



#hdfs-site.xml







hadoop.tmp.dir
/tmp/hadoop/cluster/
A base for other temp directories


fs.default.name
hdfs://127.0.0.1:9000



#mapre-site.xml







mapred.job.tracker
127.0.0.1:9001

Kumar said...

Hi Ankit,
Is it possible to give input/output path as local file system path, while running hadoop mapreduce jobs in the cluster. i.e is mapreduce jobs can take input from the local file system instaed of HDFS. If so, could you please give me simple example?

Thanks.

Anonymous said...

I have following problem when job run on the cluster..

05/04/30 09:24:55 INFO mapred.JobClient: Task Id : attempt_200504281241_0058_m_000010_1, Status : FAILED
Too many fetch-failures
05/04/30 09:24:55 WARN mapred.JobClient: Error reading task outputhttp://localhost:50060/tasklog?plaintext=true&attemptid=attempt_200504281241_0058_m_000010_1&filter=stdout
05/04/30 09:24:55 WARN mapred.JobClient: Error reading task outputhttp://localhost:50060/tasklog?plaintext=true&attemptid=attempt_200504281241_0058_m_000010_1&filter=stderr

Please help me

Bhagat Khemchandani said...
This comment has been removed by the author.
Bhagat Khemchandani said...

Hi Ankit ,
Thanks a lot for this useful tutorial
But on running bin/start-dfs.sh
I am facing this issue :
[bhagat@bhagat hadoop-0.20.2]$ bin/start-dfs.sh
starting namenode, logging to /home/bhagat/hadoop-0.20.2/bin/../logs/hadoop-bhagat-namenode-bhagat.out
bhagat@datanode1's password: bhagat@datanode2's password:
bhagat@datanode1's password: datanode1: Permission denied, please try again.

bhagat@datanode2's password: datanode2: Permission denied, please try again.
here bhagat is user by which I am running the commands and datanode1 is same machine as namenode
and datanode2 is another m/c in network

I have created passwordless key bu simply pressing enter when it asks for password upon running ssh-keygen -t rsa

Please Help
Thanks

Jayant Dhargawe said...

Thanks Ankit,

This is very helpful articles for configuring hadoop cluster...

Thanks@lots

Ankit Jain said...

Thanks Jayant

Kumar said...

Hi Ankit,

Can you please can u add some more docs about Kerberos setup for Hadoop or point to some location where i can get the complete steps to setup Kerberos for Hadoop.

Thanks

FriskyBrainiac said...

Hi there! I am actually excited to find out one thing, could you be so kind and please tell us your place of origin?

seetharamireddy said...

Hi ankit,
nice post ...

sudheer said...
This comment has been removed by a blog administrator.
kishor mahakale said...

Really good piece of knowledge, I had come back to understand regarding your website from my friend Sumit, Hyderabad And it is very useful for who is looking for HADOOP.

sudheer said...
This comment has been removed by a blog administrator.
kumar said...

You have gathered Nice information I was really impressed by seeing this information, it was very interesting and it is very useful for hadop Big data Learners

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pinkpantherprem said...

ubuntu@namenode:~/hbase/bin$ sudo ./start-hbase.sh
Error: Could not find or load main class org.apache.hadoop.hbase.util.HBaseConfTool
Error: Could not find or load main class org.apache.hadoop.hbase.zookeeper.ZKServerTool
starting master, logging to /home/ubuntu/hbase/bin/../logs/hbase-root-master-namenode.out
Error: Could not find or load main class org.apache.hadoop.hbase.master.HMaster
secondary: Permission denied (publickey).
The authenticity of host 'slave2 (10.169.59.16)' can't be established.
ECDSA key fingerprint is bc:57:d7:8e:bb:ee:bf:2c:a6:3d:97:d1:06:d4:c7:90.
Are you sure you want to continue connecting (yes/no)? The authenticity of host 'slave1 (10.164.169.217)' can't be established.
ECDSA key fingerprint is bc:a2:3d:b5:1a:fd:24:85:61:12:df:49:a3:3e:12:9e.
Are you sure you want to continue connecting (yes/no)? #localhost: ssh: Could not resolve hostname #localhost: Temporary failure in name resolution
The authenticity of host 'namenode (10.233.58.19)' can't be established.
ECDSA key fingerprint is e3:cd:0f:7f:01:4a:78:52:7f:79:c6:8e:5b:c3:02:cf.
Are you sure you want to continue connecting (yes/no)? yes
slave2: Warning: Permanently added 'slave2,10.169.59.16' (ECDSA) to the list of known hosts.
slave2: Permission denied (publickey).

slave1: Host key verification failed.

namenode: Host key verification failed.

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Joseph A. Wallace said...

Thanks for InformationHadoop Course will provide the basic concepts of MapReduce applications developed using Hadoop, including a close look at framework components, use of Hadoop for a variety of data analysis tasks, and numerous examples of Hadoop in action. This course will further examine related technologies such as Hive, Pig, and Apache Accumulo. HADOOP Online Training

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