NameNode doesn't see newly added datanodes as alive

[#1]

I have added two more hosts as datanodes via Ambari. Installation is completed successfully. When I return back Ambari dashboard tab I see DataNodes Live: 8/10 I have checked HDFS and seen Installed DataNodes 10/10. There is no apparent error. Screeshots are below.

I can see cpu cores and memory but can't disks. Total hdfs disk space didn't change. How to solve this?

/var/log/hadoop/hdfs/hadoop-hdfs-datanode-hadooptest12.log

2018-05-23 15:20:28,176 WARN  datanode.DataNode (BPServiceActor.java:retrieveNamespaceInfo(227)) - Problem connecting to server: hadooptest12.datalonga.com/StandByNN_IP:8020
2018-05-23 15:20:28,176 WARN  datanode.DataNode (BPServiceActor.java:retrieveNamespaceInfo(227)) - Problem connecting to server: hadooptest13.datalonga.com/ActiveNN_IP:8020

datanodes-live.png datanodes-dead.png

[#2 · Accepted solution]

I have solved it. It was a connection problem as logs stated. I had to modify /etc/hosts file. servers have two network card. I switched ip-names of two card.