Question 992 of 972
hardMultiple ChoiceObjective-mapped
220-1201 Practice Question: A company's file server uses a RAID 5 array with…
A company's file server uses a RAID 5 array with five 4 TB hard drives. One drive fails and is replaced. During the rebuild, the server crashes and the RAID controller reports that the array is 'Failed'. What is the most likely reason for this catastrophic failure?
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
✓
A second drive failed during the rebuild process.
In RAID 5, a single drive failure is survivable, but during rebuild, the remaining drives are under heavy read stress. If another drive fails or has an unrecoverable read error, the array fails. This is known as a 'double fault' during rebuild, a common risk with large-capacity drives.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The new drive was not properly formatted before installation.
Why it's wrong here
A new drive installed into a RAID array, especially during a rebuild, does not require pre-formatting by the user. The RAID controller itself manages the low-level formatting and integration of the new drive as it reconstructs the missing data onto it. An unformatted drive would not cause the entire RAID 5 array to fail; rather, the controller would prepare it for use, or the rebuild would simply fail to complete on that specific drive, leaving the array in a degraded state, not completely failed.
- ✗
The RAID controller cache battery is dead.
Why it's wrong here
A dead RAID controller cache battery primarily impacts write performance and data integrity during unexpected power loss events, as it's designed to flush cached data to disk. While its failure might lead to performance degradation or data loss if power is interrupted, it does not directly cause a RAID 5 array to fail during a rebuild process. The rebuild would proceed, albeit potentially slower, without the battery's protection.
- ✓
A second drive failed during the rebuild process.
Why this is correct
RAID 5 arrays are designed with single-drive fault tolerance, meaning they can continue operating with one failed drive by reconstructing data from parity and remaining disks. However, if a second drive fails *during* the rebuild process, the array loses its ability to reconstruct the missing data. With two drives simultaneously unavailable (the original failed drive and the new failure), the array's data redundancy is completely compromised, leading to total array failure and data loss.
- ✗
The rebuild was attempted while the server was under heavy load.
Why it's wrong here
Attempting a RAID rebuild under heavy server load would significantly increase the time required for the process to complete, as the controller prioritizes I/O requests for active services. While this can stress the remaining drives and controller, it typically does not cause a drive to fail or the entire array to collapse. The array would remain in a degraded but functional state until the rebuild eventually finishes, or another independent issue arises.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 18, 2026
This 220-1201 practice question is part of Courseiva's free CompTIA 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 220-1201 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.