The NetApp MetroCluster architecture is specifically designed to provide continuous data availability and disaster recovery between two geographically separated data centers. It uses synchronous replication to maintain two identical, up-to-date copies of the data at each site. In the event of a complete site failure, a switchover can be initiated to the surviving site with minimal to no data loss, allowing business operations to continue. This architecture provides a high-availability solution that extends beyond a single data center, protecting against site-wide disasters.

B. Single-node cluster: This configuration has no redundancy and represents a single point of failure, offering no disaster recovery capabilities.

C. Standalone storage system: A standalone system, by definition, lacks the inter-site replication and failover capabilities required for geographic disaster recovery.

D. Local disk mirroring: This refers to RAID mirroring (e.g., RAID-DP) within a single storage system, protecting against disk failure, not a site-wide disaster.

1. NetApp. (2022). TR-4705: MetroCluster Solution Architecture and Design. The Introduction (Section 1) states, "NetApp MetroCluster software is a unique high-availability and disaster-recovery solution... It provides continuous data availability for mission-critical applications, protecting them from a complete data center disaster."

2. NetApp. (2023). MetroCluster concepts. ONTAP 9 Documentation Center. The overview section describes MetroCluster as a solution that "provides disaster recovery with synchronous replication between two sites."