What mechanism do snapshots use to preserve a point-in-time image without duplicating data?

• A. Copy-on-write and metadata references.
• B. Full copy of the data.
• C. Inline deduplication.
• D. Versioning using a separate disk.

Answer: (A)

Snapshots preserve a point-in-time image by using copy-on-write and metadata references. Copy-on-write means the data blocks are shared between the active volume and the snapshot at creation; only when a block is written to after the snapshot is taken does the system copy the original block into the snapshot area and then apply the new write to the active data. This keeps the snapshot’s view intact without duplicating all data upfront, since unchanged blocks remain shared. Metadata references track which blocks belong to the snapshot and ensure the image remains consistent while enabling efficient storage use. The other approaches would either duplicate all data, rely on a separate deduplication path, or require a different versioning scheme, none of which achieve the same efficient point-in-time image.