In a Cloudera cluster we had a few nodes reporting the following error message in the logs under
hadoop-cmf-hdfs-DATANODE-whatever.com.log.out
The error included:
Datanode denied communication with namenode because the host is not in the include-list: : DatanodeRegistration
One solution could be to ‘Refresh Node List’ as shown in the screenshot below. Find it by clicking on the Clusters > HDFS and then click on ‘NameNode’ in the ‘Status Summary’. After that choose ‘Refresh Node List’ under the ‘Actions’ menu. YMMV
