In an IP MetroCluster configuration, the MetroCluster Mediator is a critical component that enables automatic unplanned switchover (AUSO). It resides at a third, independent site and acts as an arbitrator or witness. During a site or network failure, the surviving cluster consults the Mediator to determine if it is safe to take over services. This prevents a "split-brain" scenario where both sites might attempt to become active simultaneously, ensuring data consistency.

B. The ONTAP Controller is a primary component of the cluster but relies on the external Mediator for arbitration in an AUSO scenario.

C. Cluster Scheduler is an internal ONTAP process responsible for managing scheduled jobs, not for high-availability arbitration between sites.

D. Disk Manager is an internal ONTAP process that manages disk-level operations and has no role in MetroCluster switchover arbitration.

1. NetApp, "TR-4705: MetroCluster IP Solution Architecture and Design," Page 10. Describes the Mediator's role: "The NetApp MetroCluster Mediator... serves as a witness to prevent a split-brain scenario and automates switchover."

2. NetApp, "Install and configure a MetroCluster Mediator," Document ID: 101-000-233. States, "The Mediator provides a quorum service that enables automatic switchover in IP MetroCluster configurations."