Which backup strategy copies only changes since the last backup, and what are its trade-offs?

Which backup strategy copies only changes since the last backup, and what are its trade-offs?

• A. Incremental backups copy all data every time.
• B. Incremental backups copy only changes since last backup (faster, saves space but requires full backup chain for restore).
• C. Incremental backups delete older files to save space.
• D. Incremental backups require no prior backups for restore.

Answer: (B)

Incremental backups copy only the data that has changed since the last backup. Because you’re recording just the new or altered blocks, these backups run faster and use less storage than copying everything each time. The trade-off is in restoration: to reconstruct data, you start with the most recent full backup and then apply each incremental backup in order since that full backup. If any increment in the chain is missing or corrupted, restoring can fail or become much slower, so incremental strategies are often paired with periodic full backups to keep a reliable restore point.

Incremental backups copy only the data that has changed since the last backup. Because you’re recording just the new or altered blocks, these backups run faster and use less storage than copying everything each time. The trade-off is in restoration: to reconstruct data, you start with the most recent full backup and then apply each incremental backup in order since that full backup. If any increment in the chain is missing or corrupted, restoring can fail or become much slower, so incremental strategies are often paired with periodic full backups to keep a reliable restore point.