I started the Cloudera VM normally, But when I am doing a list on the files in HDFS, I am getting a Connection Exception as follows:
[cloudera@quickstart ~]$ hadoop fs -ls /user/
ls: Call From quickstart.cloudera/127.0.0.1 to quickstart.cloudera:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
I guess it is because of the Hadoop services not running but can somebody please suggest, when i am starting the CLoudera VM as required why getting this error?
All the basic Hadoop services should be running when you start the VM. Port 8020 is for the hadoop-hdfs-namenode service, so my guess is that service has failed and just needs to be restarted.
You can check the status of a service with
service <service-name> status
and you can restart a service with
service <service-name> restart
So 'service hadoop-hdfs-namenode restart' may be all you need. Also check the hadoop-hdfs-datanode service as it may also need to be restarted.
The services should have been running, so if they're not it means something went wrong. If you're curious or if you continue to have a problem, have a look at the NameNode logs in /var/log/hadoop-hdfs for anything that looks like a fatal error and post it back here.
My datanode service is running fine but yes the namenode servoce is not running.
I restarted it but the restart is getting failed:
[root@quickstart cloudera]# service hadoop-hdfs-datanode status
Hadoop datanode is running [ OK ]
[root@quickstart cloudera]# service hadoop-hdfs-namenode restart
no namenode to stop
Stopped Hadoop namenode: [ OK ]
starting namenode, logging to /var/log/hadoop-hdfs/hadoop-hdfs-namenode-quickstart.cloudera.out
Failed to start Hadoop namenode. Return value: 1 [FAILED]
did you resolve the issue I am facing the same issue when trying to execute a command even after starting the service and having the status say okay.
First please see the status of service using this command
sudo service hadoop-hdfs-<service_name> status;
ex- sudo service hadoop-hdfs-namenode status;
If status is stop , please try to start using below command
sudo service hadoop-hdfs-<service_name> start;
If it's running , first stop it and again restart this.
sudo service hadoop-hdfs-<service_name> stop;
sudo service hadoop-hdfs-<service_name> restart;
Hope it will work for you.
Please see these below link, i hope it will help you.
WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Problem connecting to server: 0.0.0.0/0.0.0.0:8022
From the above error it is clear that the external datanode is having trouble connecting to Namenode.
You can do one thing.
Check the status of the namenode you are connect by
Sudo Service hadoop-hdfs-namenode status
Sudo Service hadoop-hdfs-secondarynamenode status
if it has not started then you may start it by replacing the status with start if you dont have authorization you should contact the hadoop admin . Also please check the same for Secondarynamenode.