HDP - Hadoop HA

1. namenode HA
   1. Check to make sure you have at least three hosts in your cluster and are running at least three ZooKeeper servers
   2. ambari web -> services -> HDFS -> service actions -> enable namenode HA -> nameservice ID -> select hosts -> review
   3. create checkpoint
      1. login to the namenode host
      2. sudo su hdfs -l -c 'hdfs dfsadmin -safemode enter'
      3. sudo su hdfs -l -c 'hdfs dfsadmin -saveNamespace'
   4. configure components
   5. initialize journalnodes
      1. login to the namenode host
      2. sudo su hdfs -l -c 'hdfs namenode -initializeSharedEdits'
   6. start components
   7. initialize metadata
      
      1. login to the namenode host
      2. sudo su hdfs -l -c 'hdfs zkfc -formatZK'
      3. login to the additional namenode host
      4. sudo su hdfs -l -c 'hdfs namenode -bootstrapStandby'
   8. finalize HA setup
2. resourcemanager HA
   1. Check to make sure you have at least three hosts in your cluster and are running at least three ZooKeeper servers
   2. ambari web -> services -> YARN -> service actions -> enable resouremanger HA -> get started -> select hosts -> review -> configure components