How does ONTAP implement snapshot space efficiency?

• A. It uses compression to reduce space for snapshots.
• B. It uses a copy-on-write mechanism so unchanged blocks are shared and only modified blocks consume extra space.
• C. It stores full copies of blocks for every snapshot.
• D. It keeps all blocks identical across snapshots.

Answer: (B)

Snapshot space efficiency in ONTAP comes from a copy-on-write approach. When a snapshot is created, ONTAP doesn’t duplicate the data blocks. The snapshot shares the same blocks with the active file system view. If a block isn’t changed after the snapshot is taken, it is shared across all snapshots, so no extra space is used. Only when data is written to a block after the snapshot is created does ONTAP allocate a new block for the updated data, keeping the old block for the snapshot. This means space is consumed only by the changes, making multiple snapshots storage-efficient.