Changing map and reduce slots

Question

I have a datanode for which I want to change map and reduce slots. I want to set the map and reduce slots to 4 and 2 respectively. How to set the new values and where?

Answer 1

Follow these steps to set the map and reduce slots:

Step 1: Update mapred-site.xml of namenode and add following property

<property>
<name>mapred.tasktracker.map.tasks.maximum</name>
<value >4</value>
<final>true</final>
</property> 

<property>
<name>mapred.tasktracker.reduce.tasks.maximum</name>
<value >2</value>
<final>true</final>
</property>

Step 2: Update mapred-site.xml of datanode1 and add following property

<property>
<name>mapred.tasktracker.map.tasks.maximum</name>
<value >4</value>
<final>true</final>
</property> 

<property>
<name>mapred.tasktracker.reduce.tasks.maximum</name>
<value >2</value>
<final>true</final>
</property>

Step 3: Update mapred-site.xml of datanode1 and add following property

<property>
<name>mapred.tasktracker.map.tasks.maximum</name>
<value >4</value>
<final>true</final>
</property> 

<property>
<name>mapred.tasktracker.reduce.tasks.maximum</name>
<value >2</value>
<final>true</final>
</property> 

Hope this helps!