In the previous post, we saw how to setup Hadoop 2.x on single-node. Here, we will see how to set up a multi-node cluster.
Hadoop 2.x> This post concentrates on installing Hadoop 2.x a.k.a. Yarn a.k.a. next-gen on a multi-node cluster. Prerequisites:
Java 6 installed
Dedicated user for hadoop
SSH configured
Steps to install Hadoop 2.x: 1. Download tarball
You can download tarball for hadoop 2.x from here. Extract it to a folder say, /home/hduser/yarn on master and all the slaves. We assume dedicated user for Hadoop is “hduser”. NOTE: Master and all the slaves must have the same user and hadoop directory on same path.
$ cd /home/hduser/yarn
$ sudo chown -R hduser:hadoop hadoop-2.0.1-alpha 2. Edit /etc/hosts
Add the association between the hostnames and the ip address for the master and the slaves on all the nodes in the /etc/hosts file. Make sure that the all the nodes in the cluster are able to ping to each other. Important Change:
127.0.0.1 localhost localhost.localdomain my-laptop
127.0.1.1 my-laptop
If you have provided alias for localhost (as done in entries above), protocol buffers will try to connect to my-laptop from other hosts while making RPC calls which will fail. Solution:
Assuming the machine (my-laptop) has ip address “10.3.3.43″, make an entry as follows in all the other machines:
10.3.3.43 my-laptop 3. Password less SSH
Make sure that the master is able to do a password-less ssh to all the slaves. 4. Edit ~/.bashrc
export HADOOP_HOME=/home/hduser/yarn/hadoop-2.0.1-alpha
export HADOOP_MAPRED_HOME=$HADOOP_HOME
export HADOOP_COMMON_HOME=$HADOOP_HOME
export HADOOP_HDFS_HOME=$HADOOP_HOME
export YARN_HOME=$HADOOP_HOME
export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop
export YARN_CONF_DIR=$HADOOP_HOME/etc/hadoop 5. Edit Hadoop environment files
Add JAVA_HOME to following files
Add following line at start of script in libexec/hadoop-config.sh :
export JAVA_HOME=/usr/lib/jvm/java-6-openjdk-i386/ Add following lines at start of script in etc/hadoop/yarn-env.sh :
export JAVA_HOME=/usr/lib/jvm/java-6-openjdk-i386/
export HADOOP_HOME=/home/hduser/yarn/hadoop-2.0.1-alpha
export HADOOP_MAPRED_HOME=$HADOOP_HOME
export HADOOP_COMMON_HOME=$HADOOP_HOME
export HADOOP_HDFS_HOME=$HADOOP_HOME
export YARN_HOME=$HADOOP_HOME
export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop
export YARN_CONF_DIR=$HADOOP_HOME/etc/hadoop
Change the path as per your java installation. 6. Create Temp folder in HADOOP_HOME
$ mkdir -p $HADOOP_HOME/tmp 7. Add properties in configuration files
Make changes as mentioned below in all the machines:
$HADOOP_CONF_DIR/core-site.xml
8. Add slaves
Add the slave entries in $HADOOP_CONF_DIR/slaves on master machine:
slave1
slave2 9. Format the namenode
$ bin/hadoop namenode -format 10. Start Hadoop Daemons
$ sbin/hadoop-daemon.sh start namenode
$ sbin/hadoop-daemons.sh start datanode
$ sbin/yarn-daemon.sh start resourcemanager
$ sbin/yarn-daemons.sh start nodemanager
$ sbin/mr-jobhistory-daemon.sh start historyserver NOTE: For datanode and nodemanager, scripts are *-daemons.sh and not *-daemon.sh. daemon.sh does not lookup in slaves file and hence, will only start processes on master 11. Check installation
Check for jps output on slaves and master.
For master:
$ jps
6539 ResourceManager
6451 DataNode
8701 Jps
6895 JobHistoryServer
6234 NameNode
6765 NodeManager
For slaves:
$ jps
8014 NodeManager
7858 DataNode
9868 Jps
If these services are not up, check the logs in $HADOOP_HOME/logs directory to> 12. Run a demo application to verify installtion
$ mkdir in
$ cat > in/file
This is one line
This is another one
Add this directory to HDFS:
$ bin/hadoop dfs -copyFromLocal in /in Run wordcount example provided:
$ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.*-alpha.jar wordcount /in /out Check the output:
$ bin/hadoop dfs -cat /out/*
This 2
another 1
is 2
line 1
one 2 13. Web interface
1. http://master:50070/dfshealth.jsp
2. http://master:8088/cluster
3. http://master:19888/jobhistory (for Job History Server) 14. Stopping the daemons
$ sbin/mr-jobhistory-daemon.sh stop historyserver
$ sbin/yarn-daemons.sh stop nodemanager
$ sbin/yarn-daemon.sh stop resourcemanager
$ sbin/hadoop-daemons.sh stop datanode
$ sbin/hadoop-daemon.sh stop namenode 15. Possible errors
If you get a exception stack trace similar to given below:
Container launch failed for container_1350204169962_0002_01_000004 : java.lang.reflect.UndeclaredThrowableException at org.apache.hadoop.yarn.exceptions.impl.pb.YarnRemoteExceptionPBImpl.unwrapAndThrowException(YarnRemoteExceptionPBImpl.java:135)
at org.apache.hadoop.yarn.api.impl.pb.client.ContainerManagerPBClientImpl.startContainer(ContainerManagerPBClientImpl.java:101)
at org.apache.hadoop.mapreduce.v2.app.launcher.ContainerLauncherImpl$Container.launch(ContainerLauncherImpl.java:149)
at org.apache.hadoop.mapreduce.v2.app.launcher.ContainerLauncherImpl$EventProcessor.run(ContainerLauncherImpl.java:373)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:679)
Caused by: com.google.protobuf.ServiceException: java.net.UnknownHostException: Invalid host name: local host is: (unknown); destination host is: "my-laptop":40365; java.net.UnknownHostException; For more details see: http://wiki.apache.org/hadoop/UnknownHost
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:187)
at $Proxy29.startContainer(Unknown Source)
at org.apache.hadoop.yarn.api.impl.pb.client.ContainerManagerPBClientImpl.startContainer(ContainerManagerPBClientImpl.java:99)
... 5 more
Caused by: java.net.UnknownHostException: Invalid host name: local host is: (unknown); destination host is: "my-laptop":40365; java.net.UnknownHostException; For more details see: http://wiki.apache.org/hadoop/UnknownHost
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:740)
at org.apache.hadoop.ipc.Client$Connection.(Client.java:248)
at org.apache.hadoop.ipc.Client.getConnection(Client.java:1261)
at org.apache.hadoop.ipc.Client.call(Client.java:1141)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:184)
... 7 more
Caused by: java.net.UnknownHostException
... 11 more
Solution: Check the Important Change in Step 2 and apply the necessary changes.
Happy Coding!!!
- Rasesh Mori