Hadoop: There are 0 datanode(s) running and no node(s) are excluded in this operation
<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>