Role of the Failover Cluster

To ensure that a single instance of the application is only ever running on one cluster member at a time.
Why is “running on one member” crucial?
- Allows you to run “off the shelf” applications.
- Filesystems can only be mounted by one system.
- Databases typically run on one system at a time.
What happens when “run on one member” fails?
- Application runs on none of the cluster members
- Application concurrently runs on multiple cluster members -> data corruption ensues (weak data integrity guarantees).

To ensure that a single instance of the application is only ever running on one cluster member at a time.