1. Prerequisites

Ensure that the following property is defined in your hdfs-site.xml file.

<property>         
   <name>dfs.hosts.exclude</name>        
   <value>$HADOOP_CONF_DIR/excludes</value>
   <final>true</final>   
</property>                 
            

where $HADOOP_CONF_DIR is the directory for storing the Hadoop configuration files. For example, /etc/hadoop/conf.

Ensure that the following property is defined in your mapred-site.xml file.

<property>         
   <name>mapred.hosts.exclude </name>        
   <value>$HADOOP_CONF_DIR/excludes</value>
   <final>true</final>   
</property>                 
            

where $HADOOP_CONF_DIR is the directory for storing the Hadoop configuration files. For example, /etc/hadoop/conf.