Hadoop UI shows only one Datanode

Question

I've started hadoop cluster composed of on master and 4 slave nodes.

Configuration seems ok:

hduser@ubuntu-amd64:/usr/local/hadoop$ ./bin/hdfs dfsadmin -report

When I enter NameNode UI (http://10.20.0.140:50070/) Overview card seems ok - for example total Capacity of all Nodes sumes up.

The problem is that in the card Datanodes I see only one datanode.

Answer 1

I came across the same problem, fortunately, I solved it. I guess it causes by the 'localhost'.

1. Config different name for these IP in /etc/host
2. Remember to restart all the machines, things will go well.

Answer 2

It's because of the same hostname in both datanodes. In your case both datanodes are registering to the namenode with same hostname ie 'localhost' Try with different hostnames it will fix your problem.

in UI it will show only one entry for a hostname.

in "hdfs dfsadmin -report" output you can see both.