The requirement is to replicate data no more than once per hour. This specifies a scheduled, periodic data transfer, which defines an asynchronous replication strategy. NetApp SnapMirror Asynchronous is designed for this use case, providing disaster recovery by transferring Snapshot copies from a source to a destination volume based on a configurable schedule (e.g., hourly, daily). This method allows for a Recovery Point Objective (RPO) that is greater than zero, aligning perfectly with the hourly requirement.

A. MetroCluster SyncMirror provides continuous, synchronous replication for zero data loss (RPO=0) and high availability, which is far more frequent than the specified hourly schedule.

B. SnapMirror active sync is a feature of SnapMirror Synchronous that provides active-active LUN access with an RPO of zero, not a scheduled, periodic replication.

C. SnapMirror Synchronous provides zero data loss (RPO=0) by immediately replicating data writes to the destination, which does not meet the "no more than once per hour" criteria.

1. NetApp Technical Report 4015, "SnapMirror Configuration and Best Practices Guide for ONTAP 9.11.1," Page 8, Section 2.1.

"SnapMirror asynchronous replication provides disaster recovery protection by periodically creating a Snapshot copy of the source volume and replicating it to the destination volume. You can configure the schedule for replication to meet your recovery point objective (RPO)." This directly supports using asynchronous replication for scheduled transfers.

2. NetApp ONTAP 9.11.1 Documentation, "Data protection concepts," Section: "How SnapMirror asynchronous replication works."

"In asynchronous replication, Snapshot copies on a source volume are transferred periodically to a destination volume. The schedule at which transfers occur is the primary determinant of the recovery point objective (RPO)." This confirms that asynchronous replication is the scheduled method.

3. NetApp Technical Report 4705, "NetApp MetroCluster Solution Architecture and Design," Page 10, Section 1.2.

"MetroCluster provides synchronous replication between sites to protect against a site disaster... Because replication is synchronous, data is always up-to-date at both sites, providing a zero recovery point objective (RPO=0)." This confirms MetroCluster is synchronous and not suitable for the scenario.

4. NetApp ONTAP 9.11.1 Documentation, "Data protection concepts," Section: "How SnapMirror Synchronous replication works."

"In SnapMirror Synchronous (SM-S) replication, data is replicated synchronously from a source volume on a primary storage system to a destination volume on a secondary storage system. SM-S offers a zero recovery point objective (RPO)." This distinguishes synchronous replication from the required asynchronous schedule.