title: Hadoop: There are 0 datanode(s) running and no node(s) are excluded in this operation
body: <p>I deployed Hadoop cluster on VMware. They all on CentOS 7.</p>
  
  <p>Issue command jps on Master:</p>
  
  <pre><code>[root@hadoopmaster anna]# jps
  6225 NameNode
  6995 ResourceManager
  6580 SecondaryNameNode
  7254 Jps
  </code></pre>
  
  <p>Issue command jps on Slave:</p>
  
  <pre><code>[root@hadoopslave1 anna]# jps
  5066 DataNode
  5818 Jps
  5503 NodeManager
  </code></pre>
  
  <p>However, I have no idea why the live nodes on <a href="http://localhost:50070/dfshealth.html#tab-overview" rel="noreferrer">http://localhost:50070/dfshealth.html#tab-overview</a>
  shows 0. And I can't issue hdfs dfs -put in/file/f1. It shows error message:</p>
  
  <pre><code>[root@hadoopmaster hadoop]# hdfs dfs -put in/file/f1 /user
  16/01/06 02:53:14 WARN hdfs.DFSClient: DataStreamer Exception
  org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /user._COPYING_ could only be replicated to 0 nodes instead of minReplication (=1).  There are 0 datanode(s) running and no node(s) are excluded in this operation.
      at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1550)
      at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getNewBlockTargets(FSNamesystem.java:3110)
      at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:3034)
      at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:723)
      at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:492)
      at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
      at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:616)
      at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:969)
      at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2049)
      at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2045)
      at java.security.AccessController.doPrivileged(Native Method)
      at javax.security.auth.Subject.doAs(Subject.java:422)
      at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
      at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2043)
  
      at org.apache.hadoop.ipc.Client.call(Client.java:1476)
      at org.apache.hadoop.ipc.Client.call(Client.java:1407)
      at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:229)
      at com.sun.proxy.$Proxy9.addBlock(Unknown Source)
      at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:418)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:497)
      at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187)
      at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
      at com.sun.proxy.$Proxy10.addBlock(Unknown Source)
      at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.locateFollowingBlock(DFSOutputStream.java:1430)
      at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1226)
      at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:449)
  put: File /user._COPYING_ could only be replicated to 0 nodes instead of minReplication (=1).  There are 0 datanode(s) running and no node(s) are excluded in this operation.
  </code></pre>
  
  <p>I have tried other posts like </p>
  
  <pre><code>rm -R /tmp/*
  </code></pre>
  
  <p>and check ssh</p>
  
  <p>on master:</p>
  
  <pre><code>[root@hadoopmaster hadoop]# ssh hadoopmaster
  Last login: Wed Jan  6 02:56:27 2016 from hadoopslave1
  [root@hadoopmaster ~]# exit
  logout
  Connection to hadoopmaster closed.
  [root@hadoopmaster hadoop]# ssh hadoopslave1
  Last login: Wed Jan  6 02:43:21 2016
  [root@hadoopslave1 ~]# exit
  logout
  Connection to hadoopslave1 closed.
  [root@hadoopmaster hadoop]#
  </code></pre>
  
  <p>on slave:</p>
  
  <pre><code>[root@hadoopslave1 .ssh]# ssh hadoopmaster
  Last login: Wed Jan  6 03:04:45 2016 from hadoopmaster
  [root@hadoopmaster ~]# exit
  logout
  Connection to hadoopmaster closed.
  [root@hadoopslave1 .ssh]# ssh hadoopslave1
  Last login: Wed Jan  6 03:04:40 2016 from hadoopmaster
  [root@hadoopslave1 ~]# exit
  logout
  Connection to hadoopslave1 closed.
  [root@hadoopslave1 .ssh]# 
  </code></pre>