title: Can reducers and mappers be on the same data node?
body: <p>I have started reading about Big Data and Hadoop, so this question may sound very stupid to you.</p>
  
  <p>This is what I know.</p>
  
  <p>Each mapper processes a small amount of data and produces an intermediate output.
  After this, we have the step of shuffle and sort.</p>
  
  <p>Now, Shuffle = Moving intermediate output over to respective Reducers each dealing with a particular key/keys.</p>
  
  <p>So, can one Data Node have the Mapper and Reducer code running in them or we have different DNs for each?</p>