When a file stored in the origin volume is modified, what happens to the corresponding blocks in FlexCache volumes?

• A. The blocks remain unchanged until manually cleared.
• B. ONTAP automatically invalidates them through coherency messaging.
• C. They are converted to writable copies.
• D. The cache volume deletes all its data immediately.

Answer: (B)

FlexCache keeps cached data in sync with the origin through a coherency mechanism. When a file on the origin volume is modified, ONTAP automatically sends coherency messages to the FlexCache volumes to invalidate the blocks that are cached there. Those blocks become invalid, so a subsequent access from the cache will miss and cause the updated data to be fetched from the origin. This maintains consistency between origin and cache without manual intervention, and it only affects the modified blocks rather than all cached data.