I have HDP cluster v2.6.1.5 with 1 master and 2 datanode. Now, in Ambari webUI i can see Datanodes 2/2 but in hosts i can see only one Datanode. Please help

[#1]

Ambari v2.6.1.5

HDP 2.6.4.0

[#2]

could you provide some additional details? screenshots of the Ambari dashboard, HDFS service page, host list, etc.?

[#3]

Check if ambari agent is running in that datanode? you can go to ambari-host and check the host status of datanode2 .