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From Daniel Watrous <dwmaill...@gmail.com>
Subject Re: Datanodes not connecting to the cluster
Date Thu, 24 Sep 2015 19:26:47 GMT
In a further test, I tried connecting to the NameNode from hadoop-master
(where it's running) using both the hostname and the IP address.

vagrant@hadoop-master:~/src$ telnet 192.168.51.4 54310
Trying 192.168.51.4...
telnet: Unable to connect to remote host: Connection refused
vagrant@hadoop-master:~/src$ telnet localhost 54310
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused
vagrant@hadoop-master:~/src$ telnet hadoop-master 54310
Trying 127.0.1.1...
Connected to hadoop-master.
Escape character is '^]'.


As you can see the IP address or localhost connection is refused, but the
hostname connection succeeds. Is there some way to configure the namenode
to accept connections from all hosts?

On Thu, Sep 24, 2015 at 2:14 PM, Daniel Watrous <dwmaillist@gmail.com>
wrote:

> On one of the namenodes I have found the following warning:
>
> 2015-09-24 18:40:17,639 WARN
> org.apache.hadoop.hdfs.server.datanode.DataNode: Problem connecting to
> server: hadoop-master/192.168.51.4:54310
>
> On my master node I see that the process is running and has bound that port
>
> vagrant@hadoop-master:~/src$ sudo lsof -i :54310
> COMMAND  PID   USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
> java    7480 hadoop  202u  IPv4  26931      0t0  TCP hadoop-master:54310
> (LISTEN)
> java    7480 hadoop  212u  IPv4  28758      0t0  TCP
> hadoop-master:54310->localhost:47226 (ESTABLISHED)
> java    7651 hadoop  238u  IPv4  28247      0t0  TCP
> localhost:47226->hadoop-master:54310 (ESTABLISHED)
> hadoop@hadoop-master:~$ jps
> 7856 SecondaryNameNode
> 7651 DataNode
> 7480 NameNode
> 8106 Jps
>
> I don't appear to have any firewall rules interfering with traffic
> vagrant@hadoop-master:~/src$ sudo iptables --list
> Chain INPUT (policy ACCEPT)
> target     prot opt source               destination
>
> Chain FORWARD (policy ACCEPT)
> target     prot opt source               destination
>
> Chain OUTPUT (policy ACCEPT)
> target     prot opt source               destination
>
> The iptables --list output is identical on hadoop-data1. I also show a
> process attempting to connect to hadoop-master
> vagrant@hadoop-data1:~$ sudo lsof -i :54310
> COMMAND  PID   USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
> java    3823 hadoop  238u  IPv4  19304      0t0  TCP
> hadoop-data1:45600->hadoop-master:54310 (SYN_SENT)
>
> I am confused by the notation of hostname/IP:port.
> All help appreciated.
>
> Daniel
>
>
>
> On Thu, Sep 24, 2015 at 12:51 PM, Daniel Watrous <dwmaillist@gmail.com>
> wrote:
>
>> I have a multi-node cluster with two datanodes. After running
>> start-dfs.sh, I show the following processes running
>>
>> hadoop@hadoop-master:~$ $HADOOP_HOME/sbin/slaves.sh jps
>> hadoop-master: 10933 DataNode
>> hadoop-master: 10759 NameNode
>> hadoop-master: 11145 SecondaryNameNode
>> hadoop-master: 11567 Jps
>> hadoop-data1: 5186 Jps
>> hadoop-data1: 5059 DataNode
>> hadoop-data2: 5180 Jps
>> hadoop-data2: 5053 DataNode
>>
>>
>> However, the other two DataNodes aren't visible.
>> http://screencast.com/t/icsLnXXDk
>>
>> Where can I look for clues?
>>
>
>

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