Data is mirrored at the volume level. The relationship between the source volume in primary storage and the destination volume in secondary storage is called a data protection relationship. The clusters in which the volumes reside and the SVMs that serve data from the volumes must be peered. A peer relationship enables clusters and SVMs to exchange data securely.

Beginning with ONTAP 9.10.1, you can create data protection relationships between S3 buckets using S3 SnapMirror. Destination buckets can be on local or remote ONTAP systems, or on non-ONTAP systems such as AWS.

The first time you invoke SnapMirror, it performs a baseline transfer from the source volume to the destination volume. The baseline transfer typically involves the following steps:

Once a baseline transfer is complete, SnapMirror transfers only new Snapshot copies to the mirror. Updates are asynchronous, following the schedule you configure. Retention mirrors the Snapshot policy on the source. You can activate the destination volume with minimal disruption in case of a disaster at the primary site, and reactivate the source volume when service is restored.

Because SnapMirror transfers only Snapshot copies after the baseline is created, replication is fast and nondisruptive. As the failover use case implies, the controllers on the secondary system should be equivalent or nearly equivalent to the controllers on the primary system to serve data efficiently from mirrored storage.