The HA fire drill (earlier known as virtual fire drill) feature uses the Action function associated with the agent. The Action functions of the supported agents are updated to support the HA fire drill functionality - running infrastructure checks and fixing specific errors.
The infrastructure check verifies the resources defined in the VCS configuration file (main.cf) have the required infrastructure to fail over on another node. For example, an infrastructure check for the Mount resource verifies the existence of the mount directory defined in the MountPoint attribute for the resource.
You can run an infrastructure check only when the service group is online. The check verifies that the specified node is a viable failover target capable of hosting the service group.
The HA fire drill provides an option to fix specific errors detected during the infrastructure check.