title: Basic Understandings of Hadoop
body: <p>How to set the speculative execution in hadoop?
  in what configuration files we need to go and make these changes? please elaborate in step wise.</p>
  
  <p>Does the speculative execution changes should be made in Name node or in Data node? if in Data node can we set them to the particular systems like (1-10 systems in my cluster an i set speculative execution for 2,3 data node systems only)</p>