Deploying the ResourceManager HA Cluster

Update the yarn-site.xml file and configuration files and start Zookeeper, HDFS, and YARN in that order.

Copy the etc/hadoop/conf/yarn-site.xml file from the primary ResourceManager host to the standby ResourceManager host.
Make sure that the clientPort value set in etc/zookeeper/conf/zoo.cfg matches the port set in the following yarn-site.xml property:
```
<property>
 <name>yarn.resourcemanager.zk-state-store.address</name>
 <value>localhost:2181</value>
</property>
```

Start ZooKeeper. Execute this command on the ZooKeeper host machines:

su - zookeeper -c "export ZOOCFGDIR=/usr/hdp/current/zookeeper-server/conf ; export ZOOCFG=zoo.cfg; source /usr/hdp/current/zookeeper-server/conf/zookeeper-env.sh ; /usr/hdp/current/zookeeper-server/bin/zkServer.sh start"

Start HDFS.
Start YARN.
Set the active ResourceManager:
MANUAL FAILOVER ONLY: If you configured manual ResourceManager failover, you must transition one of the ResourceManagers to Active mode. Execute the following CLI command to transition ResourceManager "rm1" to Active:
```
yarn rmadmin -transitionToActive rm1
```
You can use the following CLI command to transition ResourceManager "rm1" to Standby mode:
```
yarn rmadmin -transitionToStandby rm1 
```
AUTOMATIC FAILOVER: If you configured automatic ResourceManager failover, no action is required -- the Active ResourceManager will be chosen automatically.
Start all remaining unstarted cluster services.