The question asks for a solution with the "highest possible availability." In the NetApp disaster recovery portfolio, MetroCluster is the premier solution for continuous availability. It provides synchronous replication with transparent, automatic failover, resulting in a Recovery Point Objective (RPO) of zero and a near-zero Recovery Time Objective (RTO). While other solutions like SnapMirror Synchronous also offer an RPO of zero, they require manual or scripted intervention to failover, which does not constitute the "highest possible availability." The phrase "at the lowest possible price" is a secondary constraint, meaning the cost to achieve this specific top tier of availability. MetroCluster is the only option that meets the primary requirement for continuous, transparent availability.

B. SM-S: SnapMirror Synchronous (SM-S) provides a zero RPO but does not offer automatic, transparent failover. This results in a higher RTO and a lower level of availability compared to MetroCluster.

C. SnapMirror: This typically refers to asynchronous SnapMirror, which has a non-zero RPO (potential for data loss) and does not meet the "highest possible availability" requirement.

D. SVM-DR: This is an orchestration feature built upon SnapMirror technology, most commonly asynchronous SnapMirror. It simplifies the DR process but inherits the RPO/RTO characteristics of the underlying replication, which is not the highest available.

1. NetApp Technical Report 4705: NetApp MetroCluster Solution Architecture and Design

Section: Introduction, Page 5.

Quote: "NetApp MetroCluster software is a unique high-availability and disaster recovery solution that combines array-based clustering with synchronous replication to deliver continuous availability and zero data loss. The MetroCluster configuration is designed to protect against a total failure of one of the sites or data centers by providing redundant, synchronously mirrored data on the surviving site." This document establishes MetroCluster as the solution for "continuous availability."

2. NetApp Technical Report 4529: SnapMirror Synchronous (SM-S) for ONTAP 9.5 and Later

Section: Introduction, Page 5.

Quote: "SnapMirror Synchronous (SM-S) is a feature of NetApp ONTAP software that provides synchronous data replication at the volume level for a zero recovery point objective (RPO). ... Failover is not automatic." This reference explicitly contrasts SM-S with MetroCluster by stating that failover is not automatic, thus providing a lower tier of availability.

3. NetApp ONTAP 9 Documentation: Data protection overview

Section: Comparing MetroCluster and SnapMirror features.

Content: This documentation section compares business continuity solutions, positioning MetroCluster for "Continuous data availability for mission-critical applications" with "Automatic switchover," while positioning SnapMirror Synchronous for "Zero data loss" with "Manual switchover." This hierarchy confirms MetroCluster provides the highest availability.