@mike_bronson7 Hadoop uses the attribute dfs.hosts.exclude in hdfs-site.xml as a pointer to a file where node exclusions should be adequately documented. Since there is no default value for this attribute, the Hadoop cluster will not exclude any nodes in the absence of a file location and a file in the absence of dfs.hosts.exclude If dfs.hosts.exclude is not set in your cluster, take the actions listed below. Shutdown the Namenode. Edit hdfs-site.xml and add a dfs.hosts.exclude entry with the file's location. This can be a text file with the hostname that you intend to remove should be added to the file described in dfs.hosts.exclude. Start the namenode Add the hostname to the file specified in dfs.hosts.exclude that you intend to remove when dfs.hosts.exclude is already configured. Run the following command to exclude a data node After adding the hostname to the exclusion run the below command to exclude the node from functioning as a Datanode after adding the hostname to the exclusion. $ hdfs dfsadmin -refreshNodes Below command will exclude the node from functioning as a Node Manager $ yarn rmadmin -refreshNodes After the above actions, you should see one data node marked as decommissioned in Ambari. No data blocks will be sent to this data node as YARN has already marked it as unusable Hope that answers your question
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