A database administrator is designing a backup strategy for a mission-critical database where storage space is a significant concern. The business requires the ability to restore data from any point in time within the last 30 days, with a maximum data loss of 1 hour. Which backup type, when combined with a weekly full backup, would be the most storage-efficient while meeting the RPO?
- ADaily Incremental Backups
- BDaily Differential Backups
- CWeekly Full Backups Only
- DDaily Full Backups
Show answer & explanationAnswer & explanation
Correct answer: A. Daily Incremental Backups
Incremental backups are the most storage-efficient because they only back up data that has changed since the last full or incremental backup. When combined with a weekly full backup and supplemented by hourly transaction log backups (implied by 1-hour RPO, not an option itself), this strategy meets both the storage efficiency and RPO requirements. Differential backups grow larger over time, and daily full backups consume excessive storage.
Why the other options are wrong
- B. Daily differential backups are more storage-efficient than daily fulls, but they can still grow quite large by the end of the week, as each differential includes all changes since the last full backup. Incremental backups are generally more efficient for longer retention periods with frequent changes.
- C. Weekly full backups only would result in an RPO of up to 7 days, far exceeding the 1-hour RPO requirement.
- D. Daily full backups are not storage-efficient for a 30-day retention period, as each backup is a full copy of the entire database.
Backup Storage Efficiency
Backup storage efficiency refers to minimizing the amount of disk space or network bandwidth consumed by backup operations. Incremental backups are typically the most storage-efficient as they only capture changes since the last backup, contrasting with full or differential backups which copy more data.
- Incremental backups save only new or changed data.
- Reduces storage footprint and backup window.
- Recovery can be more complex due to multiple restore steps.
Memory trick: Inc: Smallest save, longest restore. Diff: Balanced, but grows more.