CISA Practice Question: Information Systems Operations and Business Resilience
A company uses a RAID 5 array for its file server. One disk fails, and the system continues to operate. However, during the rebuild process, a second disk fails. What is the likely consequence?
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
✓
Data loss occurs
RAID 5 can tolerate a single disk failure. If a second disk fails during rebuild, the array is broken and data loss occurs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Performance degrades but data remains intact
Why it's wrong here
Performance degrades with one failure, but second failure leads to data loss.
- ✗
Data is still available from parity
Why it's wrong here
RAID 5 can only survive one failure; second failure causes data loss.
- ✗
The system automatically switches to a hot spare
Why it's wrong here
If a hot spare existed, it would have been used; the scenario implies no spare.
- ✓
Data loss occurs
Why this is correct
With two failed disks, RAID 5 cannot reconstruct data.
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 by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CISA practice question is part of Courseiva's free ISACA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISA exam.