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)

Data integrity and durability in cloud storage come from layering redundancy with verification and recovery capabilities. Replication across regions or zones creates multiple copies in separate failure domains, so a regional outage or hardware failure doesn’t wipe out data. Erasure coding adds redundancy in a storage-efficient way, allowing data to be reconstructed even if some pieces are lost. Checksums provide a way to detect any corruption that occurs during storage or transmission by validating data against its stored hash. Versioning keeps previous iterations of files, letting you recover from accidental overwrites or corruption. Data integrity validation continuously checks that stored data remains correct over time. Backups give independent copies that can be restored, and periodic restore tests confirm that those backups can actually be used to recover data when needed. Taken together, these mechanisms ensure that data remains both intact and available despite failures or corruption. The other options are incomplete because they rely on a single approach or treat verification as optional, which risks undetected corruption or unrecoverable data losses.