title: Hadoop Cluster SetUp : Data Node Not Working on Slave Machine
body: <p>I am trying to run hadoop over two machines. below mentioned is my core-site.xml file.</p>
  
  <p>10.0.x.y is working as my master machine and 10.0.x.y1 is working as slave.</p>
  
  <pre><code>&lt;configuration&gt;
      &lt;property&gt;
          &lt;name&gt;fs.default.name&lt;/name&gt;
          &lt;value&gt;hdfs://10.0.x.y:54310&lt;/value&gt;
      &lt;/property&gt;
  &lt;/configuration&gt;
  </code></pre>
  
  <p>below mentioned is my hdfs-site.xml file</p>
  
  <pre><code>&lt;configuration&gt;
          &lt;property&gt;
          &lt;name&gt;dfs.replication&lt;/name&gt;
          &lt;value&gt;1&lt;/value&gt;
      &lt;/property&gt;
      &lt;property&gt;
          &lt;name&gt;dfs.name.dir&lt;/name&gt;
          &lt;value&gt;/data/hadoop-namenode-data&lt;/value&gt;
      &lt;/property&gt;
      &lt;property&gt;
          &lt;name&gt;dfs.data.dir&lt;/name&gt;
          &lt;value&gt;/data/hadoop-datanode-data&lt;/value&gt;
      &lt;/property&gt;
  
  &lt;/configuration&gt;
  </code></pre>
  
  <p>for the command on the 10.0.x.y start-dfs.sh --- my name node and datanode on the machine 10.0.x.y is running fine but error message on the namenode.log file is </p>
  
  <pre><code>2014-07-02 15:49:08,628 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: NameNode RPC up at: TPMOPW388/10.0.7.111:54310
  2014-07-02 15:49:08,628 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Starting services required for active state
  2014-07-02 15:49:11,268 WARN org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager: Unresolved datanode registration from 10.0.40.18
  2014-07-02 15:49:11,268 ERROR org.apache.hadoop.security.UserGroupInformation: PriviledgedActionException as:root (auth:SIMPLE) cause:org.apache.hadoop.hdfs.server.protocol.DisallowedDatanodeException: Datanode denied communication with namenode: DatanodeRegistration(0.0.0.0, storageID=DS-969520512-10.0.40.18-50010-1404290045109, infoPort=50075, ipcPort=50020, storageInfo=lv=-47;cid=CID-9afd9260-85c3-4018-92a6-cb391f4cfbdd;nsid=471345421;c=0)
  2014-07-02 15:49:11,268 INFO org.apache.hadoop.ipc.Server: IPC Server handler 2 on 54310, call org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol.registerDatanode from 10.0.40.18:57523 Call#1 Retry#0: error: org.apache.hadoop.hdfs.server.protocol.DisallowedDatanodeException: Datanode denied communication with namenode: DatanodeRegistration(0.0.0.0, storageID=DS-969520512-10.0.40.18-50010-1404290045109, infoPort=50075, ipcPort=50020, storageInfo=lv=-47;cid=CID-9afd9260-85c3-4018-92a6-cb391f4cfbdd;nsid=471345421;c=0)
  org.apache.hadoop.hdfs.server.protocol.DisallowedDatanodeException: Datanode denied communication with namenode: DatanodeRegistration(0.0.0.0, storageID=DS-969520512-10.0.40.18-50010-1404290045109, infoPort=50075, ipcPort=50020, storageInfo=lv=-47;cid=CID-9afd9260-85c3-4018-92a6-cb391f4cfbdd;nsid=471345421;c=0)
          at org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager.registerDatanode(DatanodeManager.java:739)
          at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.registerDatanode(FSNamesystem.java:3929)
          at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.registerDatanode(NameNodeRpcServer.java:948)
          at org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolServerSideTranslatorPB.registerDatanode(DatanodeProtocolServerSideTranslatorPB.java:90)
          at org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos$DatanodeProtocolService$2.callBlockingMethod(DatanodeProtocolProtos.java:24079)
          at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:585)
          at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:928)
          at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2048)
          at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2044)
          at java.security.AccessController.doPrivileged(Native Method)
          at javax.security.auth.Subject.doAs(Subject.java:415)
          at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1491)
          at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2042)
  </code></pre>
  
  <p>any help is appreciated.</p>