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220-1201 Practice Question: A technician is configuring a RAID 5 array with…
A technician is configuring a RAID 5 array with three 1 TB HDDs on a motherboard RAID controller. After setup, the array works but the system occasionally freezes during heavy disk I/O. The drives are all SATA 3 Gb/s and the motherboard supports SATA 6 Gb/s. What is the most likely cause?
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
✓
The drives are overheating due to continuous I/O.
Mixing SATA speeds (3 Gb/s drives on a 6 Gb/s controller) is generally backward-compatible and should not cause freezes. The freezing during heavy I/O suggests a thermal issue, as RAID 5 rebuilds and heavy writes generate significant heat. Overheating can cause drives to throttle or the controller to lock up.
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 SATA 3 Gb/s drives are bottlenecking the SATA 6 Gb/s controller.
Why it's wrong here
SATA 3 Gb/s drives are backward compatible with SATA 6 Gb/s controllers, but they will operate at the slower 3 Gb/s speed. This speed mismatch creates a performance bottleneck, limiting the overall data throughput of the RAID array. While this results in slower I/O operations and reduced performance, it does not inherently cause the system to freeze or become unstable, as the components are still functioning within their specified, albeit limited, parameters.
- ✓
The drives are overheating due to continuous I/O.
Why this is correct
Continuous, heavy I/O operations, especially in a RAID 5 configuration involving parity calculations across multiple drives, generate significant heat. If the system's cooling solution is inadequate, the hard drives can exceed their safe operating temperatures. When drives overheat, they may throttle performance to prevent damage or, in severe cases, become unresponsive, leading to system freezes or crashes to protect data integrity and hardware.
- ✗
The RAID controller's firmware is outdated.
Why it's wrong here
Outdated RAID controller firmware can introduce various bugs, such as compatibility issues with newer drives, incorrect error handling, or sub-optimal performance algorithms. While these issues can lead to instability, data corruption, or system crashes, they are typically less directly linked to freezing specifically during heavy I/O than a thermal issue. Firmware problems often manifest as more general instability or specific operational failures rather than a direct response to sustained workload heat.
- ✗
The stripe size is set too small.
Why it's wrong here
A stripe size that is too small for the typical I/O workload means that larger files will be broken into many more small blocks across the drives. This increases the number of individual read/write operations and the overhead for the RAID controller, leading to inefficient data access and significantly reduced performance. However, an inefficient stripe size primarily impacts throughput and latency, causing the array to be slow, but it does not typically cause the entire system to freeze or become unresponsive.
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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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.