The Automatic Unplanned Switchover (AUSO) feature is a core component of NetApp MetroCluster that provides high availability. When a site-wide disaster is detected (e.g., power failure, controller failure), AUSO automatically triggers a failover to the surviving site without manual intervention. This ensures business continuity by making data accessible from the partner cluster, thus enabling a seamless transition for applications and users. This capability is fundamental to the disaster recovery promise of the MetroCluster solution.

B. Manual snapshot restore: This is a data recovery process, not a seamless, automatic failover mechanism for high availability. It involves significant downtime and manual effort.

C. Disk compression: This is a storage efficiency feature that reduces the physical space data consumes; it is unrelated to failover or disaster recovery operations.

D. Tape replication: This is a traditional backup method for long-term archival and is not used for real-time, synchronous replication or seamless failover.

NetApp ONTAP Documentation Center, "MetroCluster concepts," Section: "How unplanned switchover works." This section describes both negotiated and automatic unplanned switchovers (AUSO), which provide the seamless failover capability.

NetApp Technical Report TR-4705, "MetroCluster Solution Architecture and Design," Page 10, Section: "Unplanned Switchover (USO)." The document states, "An unplanned switchover can be initiated automatically... This capability is known as automatic unplanned switchover (AUSO)."