title: what if I decommission one of datanode in the cluster which only has two datanodes?
body: <p>I setup a hdfs cluster, which has one master(namenode) and two slaves(datanode)</p>
  
  <p>and the dfs.replication is set to be "2"</p>
  
  <p>so every block will be replicated in the two slaves, and the files in the slaves are all the same.</p>
  
  <p>my question is, if I want to decommission one of the two slaves, it always shows "Decommission In Progress", but there is no files being copied(by use sar to moniter the network)</p>
  
  <p>So I think if the cluster only have two datanodes, and the replication is set to be "2", I can not decommission any datanode, because if I decommission any of the node, there will be only one node left, so the file can not be replicated 2.</p>
  
  <p>Do you think so?</p>