What mechanisms ensure data integrity and durability in cloud storage?

• A. Replication across regions or zones, erasure coding, checksums, versioning, data integrity validation, backups, and periodic restore tests.
• B. Data is always safe without replication
• C. Only backups are needed for durability
• D. Checksums are optional

Answer: (A)

Ensuring data integrity and durability in cloud storage comes from using multiple layers that protect against corruption, hardware failures, and site-wide disasters. Replication across regions or zones creates several geographically separated copies, so losing one location doesn’t make the data inaccessible. Erasure coding packs data with parity information across many storage nodes, providing fault tolerance with less overhead than full replication and allowing recovery even when several pieces fail. Checksums verify that data hasn’t been corrupted over time or during transfer, helping detect and repair any changes or errors. Versioning preserves older states of data, enabling restoration if a file is accidentally altered or corrupted. Data integrity validation, such as regular data scrubbing, continuously checks stored data against expected fingerprints to catch latent corruption. Backups offer independent copies for disaster recovery and long-term retention. Periodic restore tests confirm that these backups can be restored successfully, ensuring the recovery process works when needed. Taken together, these mechanisms address both immediate data accuracy and long-term availability, making them essential for durable cloud storage.