What is data compression in ONTAP used for?

• A. Compression reduces the physical disk footprint by storing data in a compressed form, potentially saving space.
• B. Compression speeds up I/O by uncompressing data on the fly.
• C. Compression creates additional copies for redundancy.
• D. Compression is used only during backups.

Answer: (A)

Data compression in ONTAP is used to save storage space by storing data in a compressed form. When compression is enabled, data is compressed before it’s written to disk, so the same amount of logical data takes up less physical space. Reads are transparently decompressed so applications see the original data. This directly increases effective capacity and lowers storage costs without requiring changes to applications. The performance impact comes from the CPU work for compression and decompression, but the tradeoff is worthwhile when data compresses well. It’s not about creating extra copies, backups, or primarily about speeding up I/O; the main goal is space savings on primary storage.