title: Why is RAID not recommended for Hadoop HDFS setups?
body: <p>Various websites (like Hortonworks) recommend to not configure RAID for HDFS setups mainly because of two reasons: </p>
  
  <ol>
  <li>Speed limited to slower disk (JBOD performs better).</li>
  <li>Reliability</li>
  </ol>
  
  <p>It is recommended to use RAID on NameNode.</p>
  
  <p>But what about implementing RAID on each DataNode storage disk?</p>