title: Hadoop/Spark : How replication factor and performance are related?
body: <p>Without discussing all other performance factors, the disk space and the Name node objects, how can replication factor emproves the performance of MR, Tez and Spark.</p>
  
  <p>If we have for example 5 datanades, does it better for the execution engine to set the replication to 5 ? Whats the best and the worst value ?</p>
  
  <p>How this can be good for aggregations, joins, and map-only jobs ?</p>