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I am trying to configure a multi-node cluster of open source Hadoop. I have Hadoop 3.0 installed on the namenode and the data node. Both are running Linux (SUSE and Ubuntu). None are CentOS, RedHat or Fedora.

I have tried different settings with the .xml files (e.g., different port numbers). I essentially get the same exact error with any configuration. I have tried hdfs reformatting the namenode and rebooting the servers:

sudo -i hdfs namenode format

There is no firewall blocking the connections between the servers. I have ensured that the owner and group associated with the directory on the namenode where hadoop will write (/fs/hadoop/tmp/) to is hduser and hadoop. I have also ensure anyone can write to it (seeing that the owner, group and user all have a "w" when I use ls -l).

I can use the start-dfs.sh and start-yarn.sh scripts. They appear to work.

sudo jps return this:

2513 Jps
1667 DataNode
2468 DFSAdmin
2134 NodeManager
1849 SecondaryNameNode

In this file /usr/local/hadoop/etc/hadoop/core-site.xml I have used a local host name, an FQDN, and 0.0.0.0. I have stopped the yarn and hdfs services and formatted hdfs. Trying these different things have not helped me. The problem is that I expect the sudo -i hdfs dfsadmin -report command to work. But this is what I see after I run it:

18/01/02 04:48:38 WARN ipc.Client: Failed to connect to server: namenodesrvr/127.0.0.1:9000: try once and fail.
java.net.ConnectException: Connection refused
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
        at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
        at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:531)
        at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:495)
        at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:681)
        at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:777)
        at org.apache.hadoop.ipc.Client$Connection.access$3500(Client.java:409)
        at org.apache.hadoop.ipc.Client.getConnection(Client.java:1542)
        at org.apache.hadoop.ipc.Client.call(Client.java:1373)
        at org.apache.hadoop.ipc.Client.call(Client.java:1337)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
        at com.sun.proxy.$Proxy10.getFsStats(Unknown Source)
        at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getStats(ClientNamenodeProtocolTranslatorPB.java:626)
        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:498)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:398)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:163)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:155)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:335)
        at com.sun.proxy.$Proxy11.getStats(Unknown Source)
        at org.apache.hadoop.hdfs.DFSClient.getStateByIndex(DFSClient.java:2073)
        at org.apache.hadoop.hdfs.DFSClient.getDiskStatus(DFSClient.java:2082)
        at org.apache.hadoop.hdfs.DistributedFileSystem.getStatus(DistributedFileSystem.java:1224)
        at org.apache.hadoop.fs.FileSystem.getStatus(FileSystem.java:2350)
        at org.apache.hadoop.hdfs.tools.DFSAdmin.report(DFSAdmin.java:476)
        at org.apache.hadoop.hdfs.tools.DFSAdmin.run(DFSAdmin.java:1908)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:90)
        at org.apache.hadoop.hdfs.tools.DFSAdmin.main(DFSAdmin.java:2099)
report: Call From localhost/127.0.0.1 to namenodesrvr:9000 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused

What can I change so that I can use the sudo -i hdfs dfsadmin -report command?

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