Resource Manager UI Showing Lost datanodes

[#1]

Hello there,

In Resource manager URL, I can see 4 lost nodes and in Ambari . All the data nodes are live(up and running). Logged into the lost data node and I can see the node manager are up and running.

In Namenode UI also I can see all the data nodes are live. However why Resource manager showing the false alert. How can I rectify the false alert in Resouce manager URL?

[#2]

Unless I am mistaken, Amabri only checks the Datanode / NodeManager process is running, not that the network connection between the DataNode to the ResourceManager is possible.

SSH to the datanodes, try to telnet to the resource manager port, and report back