This guide provides instructions on setting up the ResourceManager (RM) High Availability (HA) feature in a HDFS cluster. The Active and Standby ResourceManagers embed the Zookeeper-based ActiveStandbyElector to determine which ResourceManager should be active.
![[Note]](../common/images/admon/note.png) | Note |
|---|---|
This guide assumes that an existing HDP cluster has been manually installed and deployed. It provides instructions on how to manually enable ResourceManager HA on top of the existing cluster. |
The ResourceManager was a single point of failure (SPOF) in an HDFS cluster. Each cluster had a single ResourceManager, and if that machine or process became unavailable, the entire cluster would be unavailable until the ResourceManager was either restarted or started on a separate machine. This situation impacted the total availability of the HDFS cluster in two major ways:
In the case of an unplanned event such as a machine crash, the cluster would be unavailable until an operator restarted the ResourceManager.
Planned maintenance events such as software or hardware upgrades on the ResourceManager machine would result in windows of cluster downtime.
The ResourceManager HA feature addresses these problems. This feature enables you to run redundant ResourceManagers in the same cluster in an Active/Passive configuration with a hot standby. This mechanism thus facilitates either a fast failover to the standby ResourceManager during machine crash, or a graceful administrator-initiated failover during planned maintenance.
