It is important to preserve the state of ResourceManager during the restart of RM, so as to keep the application running with minimal interruptions. The concept is that the RM preserves the application state in a store and reloads it on restart. ApplicationMasters (AM) and NodeManagers continuously poll RM for status and re-register with it when available, thus resuming the containers from saved state.
For this recipe, you will again need a running cluster and have completed the previous recipes to make sure the cluster is working fine in terms of HDFS and YARN.
master1.cyrus.commaster node and switch to user