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220-1201 Practice Question: A user complains that their computer, which uses…
A user complains that their computer, which uses a RAID 1 mirror with two identical HDDs, is running very slowly. The OS is installed on the array. The technician checks and finds that one drive has a high number of bad sectors. What should be done to restore performance and data safety?
⚠ Common exam trap
The trap here is assuming that removing the failing drive is a quick fix, when in fact it sacrifices redundancy; the exam tests whether you understand that RAID 1 requires both drives to maintain fault tolerance and performance.
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
✓
Replace the failing drive with a new one and rebuild the array.
In a RAID 1 mirror, both drives normally serve reads in parallel, so a drive with a high number of bad sectors forces the controller to retry reads and rely on the healthy mirror, degrading performance. Replacing the failing drive and rebuilding the array restores the mirror to a healthy state, recovering both performance and redundancy. Simply removing the drive would eliminate fault tolerance and leave the system vulnerable to a single point of 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.
- ✗
Remove the failing drive and continue with the good drive only.
Why it's wrong here
Removing the failing drive would allow the system to operate on the single remaining drive, but this action completely eliminates the fault tolerance provided by RAID 1 mirroring. The array would remain in a degraded state, leaving the system highly vulnerable to total data loss if the now-single operational drive were to fail. This sacrifices the primary benefit of RAID 1.
- ✓
Replace the failing drive with a new one and rebuild the array.
Why this is correct
Replacing the failing drive with a new, identical one is the correct and standard procedure for recovering a RAID 1 array. The system will then rebuild the array by copying all data from the healthy drive onto the new replacement drive, restoring full mirroring and fault tolerance. This process eliminates the performance degradation caused by retries on the failing drive and ensures data integrity and redundancy.
- ✗
Defragment both drives.
Why it's wrong here
Defragmenting drives reorganizes fragmented data for improved read/write performance but does not address physical hardware failures, bad sectors, or mechanical issues within a drive. This software-level optimization cannot repair a physically failing drive or resolve the underlying hardware problem causing slow performance and potential data corruption. It is an irrelevant action for a failing hard drive.
- ✗
Reformat the array and reinstall the OS.
Why it's wrong here
Reformatting the array would erase all data and the operating system, requiring a complete reinstall, but it would not fix the underlying hardware issue of a failing drive. The bad sectors or mechanical problems would persist, leading to continued instability and eventual failure even after a fresh installation. This is a destructive action that doesn't resolve the root cause and results in data loss.
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.
Go deeper
Related to this question
Learn chapter
Troubleshoot: Storage and RAID
Key term
RAID
RAID (Redundant Array of Independent Disks) is a data storage technology that combines multiple physical disk drives into one or more logical units for improved performance, fault tolerance, or both.
Key term
RAID 1
RAID 1 is a data storage method that creates an exact copy of data on two or more drives so that if one fails, your information is safe.
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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 CompTIA exam blueprint
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.