To add new nodes to the cluster:
1. Add the network addresses of the new nodes to the include file.
hdfs-site.xml
<property>
<name>dfs.hosts</name>
<value>/<hadoop-home>/conf/includes</value>
<final>true</final>
</property>
mapred-site.xml
<property>
<name>mapred.hosts</name>
<value>/<hadoop-home>/conf/includes</value>
<final>true</final>
</property>
Datanodes that are permitted to connect to the namenode are specified in a
file whose name is specified by the dfs.hosts property.
Includes file ...