hadoop-common-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Steve Loughran <ste...@apache.org>
Subject Re: datanode can not connect to the namenode
Date Mon, 15 Feb 2010 10:53:37 GMT
Marc Sturlese wrote:
> Hey there I have a hadoop cluster build with 2 servers. One node (A) contains
> the namenode, a datanode, the jobtraker and a tasktraker.
> The other node(B) just has a datanode and a tasktraker.
> I set up correctly hdfs with ./start-hdfs.sh
> When I try to set up MapReduce with ./start-mapred.sh the TaskTraker of node
> (B) can not connect to the namenode. The log will keep throwing:
> INFO org.apache.hadoop.ipc.Client: Retrying connect to server:
> mynamenode/ Already tried 8 time(s)
> I think maybe something is missing in /etc/hosts file or this hadoop
> property is not set correctly:
> <property>
>   <name>dfs.datanode.address</name>
>   <value></value>
>   <description>
>     The address where the datanode server will listen to.
>     If the port is 0 then the server will start on a free port.
>   </description>
> </property>
> I try on the namenode:
> telnet localhost 8021
> telnet 8021
> Both cases I get:
> telnet: Unable to connect to remote host: Connection refused

That's the Namenode that isn't there, which should be on at 

You can see what ports really are open on the namenode by identifying 
the process (jps -v will do that) then netstat -a -p | grep PID , where 
PID= process ID of the namenode.

If you can telnet to port 8021 when logged in to the NN, but not 
remotely, it's your firewall or routing interfering

View raw message