Managing host participation for HDFS and YARN
You can configure Ambari to manage which hosts in a cluster are included and excluded from participating in cluster operations for HDFS and YARN services.
Both HDFS and YARN can control which hosts in a cluster are included and excluded from participating in the cluster. HDFS uses the dfs.hosts and dfs.hosts.exclude properties to define those datanode hosts allowed and those not allowed to connect to the NameNode. YARN uses user-definable files configured through the yarn.resourcemanager.nodes.include-path and yarn.resourcemanager.nodes.exclude-path properties to define those hosts running the NodeManager component allowed and those not allowed to communicate with the ResourceManager. When the contents of these files are modified, both the HDFS NameNode and YARN ResourceManager must be notified of these changes by invoking the -refreshNodes commands through dfsadmin for HDFS and rmadmin for YARN. You can configure Ambari to manage host participation.