2.3.1.2. Starting and Testing HDFS and MapReduce

In order to check that the configuration has been set up correctly, start up HDFS and MapReduce and try to run some simple jobs.

On the NameNode host:

su $HDFS_USER
/usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf start namenode

On the SecondaryNameNode host:

su $HDFS_USER
/usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf start secondarynamenode

On each DataNode host:
```
su root
/usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf start datanode
```
Note
You must start DataNodes as root because they use a privileged port.

	Note
You must start DataNodes as `root` because they use a privileged port.

On the JobTracker host:

su $MAPREDUCE_USER
/usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf start jobtracker

On the History Server host:

su $MAPREDUCE_USER
/usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf start historyserver

On each TaskTracker host:

su $MAPREDUCE_USER
/usr/lib/hadoop/bin/hadoop-daemon.sh --config /etc/hadoop/conf start tasktracker

Open Kerberos administration. On the KDC:
```
/usr/sbin/kadmin.local
```
Create a test hdfs principal. At the kadmin.local prompt:
```
addprinc hdfs@EXAMPLE.COM
```
You are asked to enter and confirm a password for the principal.
Exit kadmin.local:
```
exit
```
On a machine in the cluster, switch to the hdfs UNIX user and then log into Kerberos:
```
su $HDFS_USER
kinit
```

Run some sample MapReduce jobs, like teragen and terasort:

/usr/lib/hadoop/bin/hadoop jar /usr/lib/hadoop/hadoop-examples.jar teragen 100000 
                                /test/10gsort/input
/usr/lib/hadoop/bin/hadoop jar /usr/lib/hadoop/hadoop-examples.jar terasort 
                                /test/10gsort/input /test/10gsort/output

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