CISA Practice Question: Information Systems Operations and Business Resilience
An organization uses RAID 5 for its database server. Which of the following is the PRIMARY advantage of RAID 5?
⚠ Common exam trap
CISA often tests the distinction between fault tolerance and other RAID benefits, and candidates may confuse RAID 5's read performance improvements or capacity utilization with its primary advantage, overlooking that fault tolerance is the key differentiator for database servers.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Fault tolerance with one disk failure
RAID 5 uses block-level striping with distributed parity, allowing the array to survive a single disk failure without data loss. When one drive fails, the missing data can be reconstructed from parity information stored on the remaining drives. This fault tolerance is the primary advantage for a database server, ensuring availability and data integrity in case of a single disk failure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Simplified backup process
Why it's wrong here
RAID 5 provides redundancy and read performance, not backup; it cannot restore deleted or corrupted data, only survive a single drive failure. Simplified backup fits snapshot or replication technologies, which are appropriate when recovery point objectives demand point-in-time copies rather than disk fault tolerance.
- ✗
Increased storage capacity without parity overhead
Why it's wrong here
RAID 5 stripes data with distributed parity, so parity consumes one drive's worth of capacity; usable space is (n-1) drives, not n. Capacity without parity overhead describes RAID 0 or a spanned volume, which is the right choice when maximum raw capacity and speed matter and redundancy is not required.
- ✓
Fault tolerance with one disk failure
Why this is correct
RAID 5 stripes data with distributed parity across all disks, so if one disk fails the array continues operating and data is reconstructed from parity. This provides fault tolerance against a single disk failure without duplicating full copies.
- ✗
Improved read performance
Why it's wrong here
RAID 5's primary advantage is fault tolerance through distributed parity, enabling continued operation after one drive fails; improved read performance is a secondary benefit, not the defining purpose. Read performance alone is the reason to choose RAID 0 or a striped array where redundancy is unnecessary.
Quick reference
RAID Level Comparison
| RAID Level | Min Disks | Fault Tolerance | Read | Write | Usable Capacity |
|---|---|---|---|---|---|
| RAID 0 | 2 | None | Excellent | Excellent | 100% |
| RAID 1 | 2 | 1 disk | Good | Moderate | 50% |
| RAID 5 | 3 | 1 disk | Good | Moderate | 67–94% |
| RAID 6 | 4 | 2 disks | Good | Lower | 50–88% |
| RAID 10 | 4 | 1 disk per mirror | Excellent | Good | 50% |
RAID is not a backup strategy — it protects against disk failure but not against accidental deletion, ransomware, or site-level events.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISACA exam blueprint
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