1. What is Backup?
- Definition: A backup is a copy of data stored securely to recover it in case of loss, corruption, or disaster.
- Purpose: To ensure data safety and continuity.
2. Types of Backups
A. Full Backup
- What it is: A complete copy of all selected data.
- Advantages:
- Simplifies restoration (one file needed).
- Most reliable backup type.
- Disadvantages:
- Time-consuming to create.
- Requires more storage space.
- Use Case: Ideal for the first backup or when data changes significantly.
B. Incremental Backup
- What it is: Backs up only data that has changed since the last backup (any type).
- Advantages:
- Fast and uses less storage.
- Efficient for frequent backups.
- Disadvantages:
- Restoration is slow (requires the full backup + all incremental backups).
- Use Case: Best for frequent backups of constantly changing data.
C. Differential Backup
- What it is: Backs up all changes made since the last full backup.
- Advantages:
- Faster restoration than incremental (needs only full backup + last differential).
- Simpler to manage than incremental backups.
- Disadvantages:
- Larger in size than incremental.
- Slower than incremental for daily backups.
- Use Case: Suitable for mid-level frequency backups.
3. Comparison of Backup Types
| Feature | Full Backup | Incremental Backup | Differential Backup |
|---|---|---|---|
| Data Backed Up | Entire dataset | Changes since the last backup | Changes since the last full backup |
| Backup Speed | Slow | Fast | Medium |
| Storage Required | High | Low | Medium |
| Restoration Speed | Fast (single backup) | Slow (requires multiple backups) | Medium (two backups needed) |
4. Use Cases for Each Backup Type
- Full Backup: Initial setup or when data integrity is critical.
- Incremental Backup: For daily or frequent updates with minimal storage.
- Differential Backup: Weekly backups or when a balance between speed and storage is needed.
5. Important Points to Remember
- A Full Backup is the foundation for both Incremental and Differential backups.
- Incremental Backup requires all previous incremental files for restoration.
- Differential Backup grows larger over time but simplifies recovery.
- Regular backups ensure data protection and minimize loss risk.
Multiple-Choice Questions (MCQs)
1. What is a full backup?
- A. A backup that only stores changed files.
- B. A backup that creates a complete copy of all selected data.
- C. A backup that only stores changes since the last backup.
- D. A backup of data created automatically in real time.
Answer: B
2. Which type of backup requires the most storage space?
- A. Incremental
- B. Differential
- C. Full
- D. Snapshot
Answer: C
3. An incremental backup saves:
- A. All files regardless of changes.
- B. Only the changes since the last full backup.
- C. Only the changes since the last backup of any type.
- D. Only files created after the backup schedule started.
Answer: C
4. What is a differential backup?
- A. A backup that stores all data regardless of changes.
- B. A backup that stores only changes made since the last incremental backup.
- C. A backup that stores changes made since the last full backup.
- D. A backup that continuously updates data in real time.
Answer: C
5. Which of the following is the fastest type of backup to create?
- A. Full Backup
- B. Incremental Backup
- C. Differential Backup
- D. Real-time Backup
Answer: B
6. During restoration, which backup type requires combining all previous backups?
- A. Full Backup
- B. Incremental Backup
- C. Differential Backup
- D. Snapshot Backup
Answer: B
7. Which backup type is ideal for minimizing storage usage during daily backups?
- A. Full Backup
- B. Incremental Backup
- C. Differential Backup
- D. Cloud Backup
Answer: B
8. Restoration from a differential backup requires:
- A. Only the latest differential backup.
- B. The last full backup and the latest differential backup.
- C. All previous incremental backups.
- D. The entire dataset in its original state.
Answer: B
9. What is the main disadvantage of an incremental backup?
- A. High storage requirements
- B. Slow backup speed
- C. Time-consuming restoration process
- D. High processing power needed during backup
Answer: C
10. Which of the following backup types is most suitable for a complete system recovery?
- A. Full Backup
- B. Incremental Backup
- C. Differential Backup
- D. Selective Backup
Answer: A
11. Incremental backups depend on which of the following for complete restoration?
- A. Only the latest incremental backup
- B. The last full backup and all subsequent incremental backups
- C. The most recent full and differential backups
- D. Only the initial full backup
Answer: B
12. Which backup type grows in size as more changes are made since the last full backup?
- A. Full Backup
- B. Incremental Backup
- C. Differential Backup
- D. Real-time Backup
Answer: C
13. The advantage of a full backup over other types is:
- A. Faster backup creation time.
- B. Minimal storage space requirement.
- C. Simplified restoration process.
- D. Supports real-time data changes.
Answer: C
14. Which type of backup is best for daily use with minimal data changes?
- A. Full Backup
- B. Incremental Backup
- C. Differential Backup
- D. Mirrored Backup
Answer: B
15. How many backups are required to restore data using a differential backup strategy?
- A. Only one (the latest differential backup)
- B. Two (the full backup and the latest differential backup)
- C. All differential backups created so far
- D. None, as differential backups store all changes
Answer: B
16. What is the primary disadvantage of a differential backup compared to an incremental backup?
- A. Higher storage space requirements.
- B. Slower restoration time.
- C. Dependence on previous backups.
- D. Complex backup creation process.
Answer: A
17. Which backup strategy is commonly used as the first step in a backup schedule?
- A. Full Backup
- B. Incremental Backup
- C. Differential Backup
- D. Synthetic Backup
Answer: A
18. If a file is modified multiple times, when will it be backed up during an incremental backup?
- A. Every time it is modified.
- B. Only during the next incremental backup.
- C. During the next full backup only.
- D. Only if it matches a pre-defined rule.
Answer: B