-Data Nodes not seeing NameNode / Task Trackers not seeing JobTracker
Ronan Lehane 2012-07-16, 18:35
I was wondering if anyone could help me figure out what's going wrong in my
five node Hadoop cluster, please?
It consists of:
All DataNodes have been kicked off by running start-dfs.sh on the NameNode
All TaskTrackers have been kicked off by running start-mapred.sh on the
When I try to execute a simple wordcount job from the NameNode I receive
the following error:
12/07/16 19:25:22 ERROR security.UserGroupInformation:
PriviledgedActionException as:hduser cause:java.net.ConnectException: Call
to jobtracker/10.21.68.218:54311 failed on connection exception:
java.net.ConnectException: Connection refused
If I check the jobtracker:
1. I can ping in both directions by both IP and Hostname
2. I can see that the jobtracker is listening on port 54311
tcp 0 0 127.0.0.1:54311 0.0.0.0:*
LISTEN 1001 425093 21542/java
3. Telnet to this port from the NameNode fails with "Connection Refused"
telnet: Unable to connect to remote host: Connection refused
This issue can be worked around by moving the JobTracker functionality to
the NameNode, but when this is done the job is executed on the NameNode
rather than distributed across the cluster.
Checking the log files on the slaves nodes, I see Server Not Available
messages referenced at the below wiki.
The Data Nodes not seeing the NameNode and the Task Trackers not seeing
Checking the JobTracker web interface, it always states there is only 1
I've checked the 5 troubleshooting steps provided but it all looks to be ok
in my environment.
Would anyone have any idea's of what could be causing this?
Any help would be appreciated.