What is data deduplication in ONTAP and where is it typically applied?

• A. It converts all data to a common format and improves read performance.
• B. It encrypts data blocks to save space.
• C. It duplicates data blocks to improve write performance.
• D. It eliminates duplicate data blocks within a volume/aggregate to save space.

Answer: (D)

Data deduplication in ONTAP is a space-saving technique that eliminates duplicate data blocks within a volume or aggregate. It works by scanning storage blocks, identifying identical data, storing a single copy of the block, and replacing every duplicate with a reference to that copy. This is commonly applied to primary data stored in ONTAP volumes (FlexVols) or within an aggregate, with the most benefit seen for data types that contain many repeating blocks—such as virtual machines, backups, and shared files. It reduces total capacity usage without changing how data is read, though it adds some CPU overhead and background processing. It’s not about encryption or boosting write performance; it’s about saving space by removing redundancy.