How does ONTAP ensure data coherency after an origin modification that affects data cached in FlexCache?

How does ONTAP ensure data coherency after an origin modification that affects data cached in FlexCache?

• A. By automatically updating cache blocks with new origin data.
• B. By invalidating modified blocks through coherency messaging.
• C. By discarding the entire cache volume.
• D. By performing a full resync of the origin to the cache.

Answer: (B)

When the origin modifies data, ONTAP uses a cache coherence mechanism to keep FlexCache from serving stale data. It sends coherence messages that invalidate the affected cached blocks. Once those blocks are invalidated, any subsequent read must fetch the latest data from the origin, ensuring correctness. This approach is efficient because it only targets the blocks that changed, rather than discarding the whole cache or performing a full resync. In short, modified blocks are marked invalid so the next access retrieves fresh data from the origin, maintaining data coherency.

When the origin modifies data, ONTAP uses a cache coherence mechanism to keep FlexCache from serving stale data. It sends coherence messages that invalidate the affected cached blocks. Once those blocks are invalidated, any subsequent read must fetch the latest data from the origin, ensuring correctness. This approach is efficient because it only targets the blocks that changed, rather than discarding the whole cache or performing a full resync. In short, modified blocks are marked invalid so the next access retrieves fresh data from the origin, maintaining data coherency.