title: HRegionServer cannot communicate with HMaster
body: <p>I have a 3-node Hadoop cluster (master and 2 slaves) with Hbase installed. Zookeeper and HMaster were installed on the Hadoop master node. After I started HBase Cluster by calling <code>start-hbase.sh</code>, the HMaster and the 2 HRegionServer processes were started. </p>
  
  <p>However, the HBase cluster showed:</p>
  
  <blockquote>
    <p>"Waiting for region servers count to settle..."</p>
  </blockquote>
  
  <p>When I checked the log file on slaves, it showed an error message as </p>
  
  <blockquote>
    <p>"Opening socket connection to server localhost/127.0.0.1:2181. Will
    not attempt to authenticate using SASL (unknown error)"</p>
  </blockquote>
  
  <p>Not sure what that meant. I guess that the HRegionServer was trying to connect to localhost instead of the master node, which had the Zookeeper and HMaster installed. I have confirmed that communication between Master and Slaves through SSH was working either way, and all the physical IPs were correctly defined in /etc/hosts files. </p>
  
  <p>Can any of you point out what could went wrong to interrupt the communication from HRegionServers to HMaster?</p>