Which solution will meet these requirements with the LEAST operational overhead?

Explanations:

While copying data to an Amazon S3 bucket and replicating it to a secondary Region is a viable backup method, it does not support direct access using the same CIFS and NFS protocols. This would require additional steps to access the data in the secondary Region, resulting in higher operational overhead.

Creating a backup of FSx for ONTAP volumes and copying them to a secondary Region can ensure data recovery, but this process involves creating a new FSx instance from the backup, which may take time and not provide real-time access to the replicated data using the same protocols. This results in operational overhead compared to a more streamlined replication process.

Creating an FSx for ONTAP instance in the secondary Region and using NetApp SnapMirror allows for real-time, efficient data replication with minimal operational overhead. This solution supports both CIFS and NFS protocols, enabling direct access to the replicated data in the secondary Region without additional configuration or steps.

While Amazon EFS can replicate data to a secondary Region, migrating existing data and switching protocols from FSx for ONTAP to EFS could involve significant effort. EFS primarily supports NFS, which might not meet the requirement for CIFS shares without additional configurations or solutions, leading to increased operational overhead.