The requirement is for a zero Recovery Point Objective (RPO) solution that protects specific volumes and ensures application writes fail if they cannot be replicated. SnapMirror Synchronous (SM-S) in StrictSync mode is designed for this exact scenario. It operates at the volume level, providing granular protection. In StrictSync mode, a write I/O is not acknowledged to the application until it is committed on both the primary and secondary storage systems. If the write to the secondary fails, the primary write also fails, guaranteeing data consistency and a true zero RPO, which is essential for the mission-critical application described.

A. SnapMirror Synchronous using Sync mode: In Sync mode, if replication to the secondary fails, the primary system continues to accept writes, breaking the zero RPO guarantee and not meeting the write-failure requirement.

B. Mirrored aggregates using SyncMirror: SyncMirror operates at the aggregate level, protecting all volumes within it, not a select number of volumes as the customer requires.

D. Mirrored SVMs using MetroCluster: MetroCluster is a site-level disaster recovery solution that protects entire SVMs or aggregates. It is excessive and does not meet the specific requirement of protecting only select volumes.

1. NetApp ONTAP 9 Documentation, Data protection, "SnapMirror Synchronous modes of operation":

"In StrictSync mode, the primary I/O is not acknowledged to the client application until it is committed to the journal log on both the primary and secondary clusters. If the write to the secondary cluster is not successful, the client I/O fails. This ensures that the primary and secondary are always identical." (This supports option C).

"In Sync mode, ...If the write to the secondary cluster is not successful, the secondary is marked as out-of-sync, but client I/O on the primary is not affected." (This refutes option A).

2. NetApp ONTAP 9 Documentation, Disks and aggregates management, "How SyncMirror implementation works":

"SyncMirror technology provides synchronous mirroring of aggregates... A mirrored aggregate, as the name implies, is an aggregate for which a complete duplicate copy of the data is maintained on two sets of disks (plexes)." (This refutes option B by confirming its scope is the entire aggregate).

3. NetApp Technical Report TR-4705: NetApp MetroCluster Solution Architecture and Design, Section: "MetroCluster Overview":

"A NetApp MetroCluster configuration is a high-availability and disaster recovery solution that combines array-based clustering with synchronous mirroring to provide continuous data availability at a site level." (This refutes option D by confirming its scope is site-level).