You have deployed volume-level replication with NetApp Synchronous SnapMirror replication technology. In this scenario, which two statements are…

NetApp SnapMirror Synchronous (SM-S) replication offers two distinct modes that govern I/O behavior during a replication failure.

The Sync mode prioritizes application availability on the primary site. If a write to the secondary volume cannot be completed, the primary system breaks the synchronous relationship, marks it as "out-of-sync," and allows the application I/O to succeed on the primary volume.

Conversely, the StrictSync mode prioritizes data consistency, guaranteeing a zero Recovery Point Objective (RPO). In this mode, if a write to the secondary volume fails, the I/O request to the primary volume is also failed. This ensures the primary and secondary volumes remain identical at all times.

A. This statement incorrectly describes Sync mode. In Sync mode, the application I/O succeeds on the primary even if the secondary write fails, prioritizing availability over strict synchronicity.

B. This statement incorrectly describes StrictSync mode. StrictSync mode fails the primary I/O if the secondary write is not completed to maintain a zero RPO.

1. NetApp Technical Report TR-4732: SnapMirror Synchronous for ONTAP 9.5 and Later.

Page 7, Section 2.1, "SnapMirror Synchronous Modes":

Regarding Sync mode: "If the secondary is not available, the primary I/O is allowed to proceed, and the relationship goes out of sync." This supports option C.

Regarding StrictSync mode: "If the secondary is not available, the primary I/O is failed. This mode guarantees that the primary and secondary are always identical." This supports option D.

2. NetApp ONTAP 9.12.1 Documentation, "SnapMirror Synchronous replication modes."

Sync mode (mode Sync): "If a write to the secondary fails for any reason, the primary storage system breaks the SnapMirror relationship to allow writes to continue to the primary volume." This validates the correctness of option C and invalidates option A.

StrictSync mode (mode StrictSync): "If a write to the secondary fails for any reason, the client is not sent an acknowledgement of a successful write and the application I/O fails. This ensures that the primary and secondary are always identical." This validates the correctness of option D and invalidates option B.