In a NetApp SnapMirror disaster recovery (DR) relationship, the destination volume is read-only by default to ensure data integrity. To activate this volume for read/write data access during a failover event, the SnapMirror relationship must be broken. The "break" operation severs the replication link, changes the destination volume's state from Data Protection (DP) to Read/Write (RW), and makes it an independent, active volume. This is the standard procedure for failing over to a secondary site.

A. update: A SnapMirror update synchronizes data from the source to the destination. The destination volume remains read-only during and after this process.

B. delete: Deleting the relationship is a permanent removal of the replication configuration. While it makes the destination writable, it is not the correct failover procedure and complicates failback.

C. resync: A resync operation is used to re-establish a broken relationship, typically after a failover, to prepare for failback. It makes the target volume read-only again.

1. NetApp ONTAP Documentation: Data protection overview. In the section "Disaster recovery workflow," the first step after a disaster is to "Break the SnapMirror relationship to make the destination volume read/write."

Source: NetApp ONTAP 9 Documentation Center, "Break a SnapMirror relationship".

2. NetApp Technical Report TR-4015: SnapMirror Configuration and Best Practices Guide for ONTAP 9. Section 5.1, "Disaster Recovery Workflow," explicitly states: "The first step in the failover process is to break the SnapMirror relationship between the source and the destination volumes. The snapmirror break command makes the destination volume read/write and available for use."

Source: NetApp TR-4015, Page 33, Section 5.1.

3. NetApp BlueXP Documentation: Replicating data between systems. The documentation for managing replication relationships describes the "Break" action. It states, "You can break the replication relationship between a source and destination. This is typically done when you want to fail over to the destination system in a disaster recovery scenario."

Source: NetApp BlueXP Documentation, "Managing replication relationships".