Which backup method is most storage-efficient but may require the longest time to complete a restore?

Which backup method is most storage-efficient but may require the longest time to complete a restore?

• A. Full Backup
• B. Incremental Backup
• C. Differential Backup
• D. 3-2-1 Backup Rule

Answer: (B)

Incremental backups store only the data that has changed since the last backup, which makes them highly storage-efficient. Because each new backup only records new or modified blocks, the amount of data saved grows slowly, allowing many backup cycles to fit in limited space. But this efficiency comes with a trade-off in restore time. To rebuild the exact state at a given point, you must first restore the baseline full backup, then repeatedly apply every subsequent incremental backup in order until you reach the desired point in time. If there are many increments, the restore process can take considerably longer than restoring from a single full backup or from a recent differential backup. A full backup copies everything every time, so restores are fast but use a lot more storage. A differential backup copies everything changed since the last full backup, so restore is quicker than incremental but the backup size grows until the next full backup. The 3-2-1 rule is about having multiple copies across different media and locations, not a backup method itself, so it doesn’t directly answer the restore-time question.

Incremental backups store only the data that has changed since the last backup, which makes them highly storage-efficient. Because each new backup only records new or modified blocks, the amount of data saved grows slowly, allowing many backup cycles to fit in limited space.

But this efficiency comes with a trade-off in restore time. To rebuild the exact state at a given point, you must first restore the baseline full backup, then repeatedly apply every subsequent incremental backup in order until you reach the desired point in time. If there are many increments, the restore process can take considerably longer than restoring from a single full backup or from a recent differential backup.

A full backup copies everything every time, so restores are fast but use a lot more storage. A differential backup copies everything changed since the last full backup, so restore is quicker than incremental but the backup size grows until the next full backup. The 3-2-1 rule is about having multiple copies across different media and locations, not a backup method itself, so it doesn’t directly answer the restore-time question.