Recovery for the ResourceManager

After a restart or failover, the active ResourceManager recovers the ResourceManager state based on the checkpoints provided in the ResourceManager state store. During recovery, the ResourceManager resumes applications and tasks that were running prior to the failover but were not completed.

Two implementations of the ResourceManager state store are available:

• FileSystemRMStateStore. Enables implicit write access to a single ResourceManager node. filesystem provides fencing implicitly and its state store implementation provides better scalability and failover performance than the ZKRMStateStore. The state store is also naturally protected by filesystem replication. By default, FileSystemRMStateStore is the state store implementation for the ResourceManager and the ResourceManager state store is maintained in the following MapR filesystem volume: /var/mapr/cluster/yarn/rm/system.
• ZKRMStateStore. Enables implicit write access to a single ResourceManager node. This is usually recommended for HA implementations where YARN is running on HDFS. However, FileSystemRMStateStore is recommended in a MapR cluster.