CompTIA DataSys+ (DS0-001)Business ContinuityMedium
A database administrator is evaluating backup strategies for a large production database (10 TB). Daily full backups take 8 hours to complete and require significant storage. The business requires an RPO of 24 hours. To reduce backup window and storage, differential backups are proposed. If the initial full backup is done on Sunday, and daily differential backups are taken Monday through Saturday, how much data, on average, would need to be restored if a failure occurs on Wednesday morning before the daily differential backup?
- AThe Sunday full backup, the Monday differential, and the Tuesday differential backups.
- BThe Sunday full backup, and the most recent differential backup (Tuesday's).
- COnly the Monday differential backup.
- DThe Sunday full backup and the Monday differential backup.
Show answer & explanationAnswer & explanation
Correct answer: B. The Sunday full backup, and the most recent differential backup (Tuesday's).
To restore using differential backups, you need the last full backup and the latest differential backup. If a failure occurs on Wednesday morning, the last full backup would be from Sunday, and the last completed differential backup would be from Tuesday. Therefore, you would restore the Sunday full backup and the Tuesday differential backup.
Why the other options are wrong
- A. This describes restoring with incremental backups, where each subsequent backup builds on the previous incremental, not differential.
- C. This is incorrect; you always need the last full backup as the base for a differential restore.
- D. This would be true for an incremental backup strategy, not differential.
Differential Backup Restore
To restore data from a differential backup strategy, you need the last full backup and the most recent differential backup.
- Differential backups store changes since the last full backup.
- Faster to restore than incremental backups (fewer files).
- Requires more storage than incremental backups (cumulative changes).
Memory trick: Differential: Full + one Diff. Incremental: Full + many Inc.