title: datanode is showing dead, how to bring it alive
body: <p>I have added 2 datanodes into,mapred.include,slaves files.</p>
  
  <p>checked hadoop dfsadmin -report command, found below status.</p>
  
  <p>Datanodes available: 0 (2 total, 2 dead)</p>
  
  <p>How to bring them alive ? Please help me out.</p>