The correct answer is that the array continues to function, but performance may decrease until the drive is replaced. This is because RAID 5 uses distributed parity, meaning parity data is spread across all drives in the array, allowing it to tolerate a single drive failure without any data loss. When one drive fails, the system enters a degraded state where it must calculate missing data from the remaining drives and parity information on the fly, which slows read and write operations. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of RAID fault tolerance versus backup—a common trap is assuming a single failure causes immediate data loss, but RAID 5 is designed for exactly this resilience. Remember that usable space in a three-drive RAID 5 is (n-1) drives, so 4 TB from three 2 TB drives confirms one drive’s worth is parity. Memory tip: “RAID 5 keeps you alive with one drive’s dive—two is a grave.”
220-1201 Storage Devices Practice Question
This 220-1201 practice question tests your understanding of storage devices. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A technician is troubleshooting a server that uses a RAID 5 array with three 2 TB HDDs. The array reports 4 TB of usable space. One drive fails. What is the immediate impact on data availability?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The array continues to function, but performance may decrease until the drive is replaced.
RAID 5 can tolerate one drive failure without data loss because parity data is distributed across all drives. The array will continue to operate in a degraded state until the failed drive is replaced and rebuilt. A second failure would cause data loss.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
All data is lost because RAID 5 cannot handle any drive failures.
Why it's wrong here
RAID 5 is designed to survive a single drive failure without data loss.
✓
The array continues to function, but performance may decrease until the drive is replaced.
Why this is correct
With one failed drive, the array is in a degraded state but still accessible; performance may drop due to parity calculations.
Related concept
Read the scenario before looking for a memorised answer.
✗
The usable capacity drops to 2 TB until the drive is replaced.
Why it's wrong here
Usable capacity remains 4 TB; only redundancy is reduced until the drive is replaced.
✗
The array automatically switches to RAID 0 to maintain performance.
Why it's wrong here
RAID arrays do not change RAID levels automatically; the array remains in RAID 5 degraded mode.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Storage Devices — This question tests Storage Devices — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The array continues to function, but performance may decrease until the drive is replaced. — RAID 5 can tolerate one drive failure without data loss because parity data is distributed across all drives. The array will continue to operate in a degraded state until the failed drive is replaced and rebuilt. A second failure would cause data loss.
What should I do if I get this 220-1201 question wrong?
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A technician is troubleshooting a server that uses a RAID 5 array with three 1TB HDDs. One drive fails, and the technician replaces it with a new 1TB HDD. After rebuilding, the array reports only 1.8TB of usable space. What is the most likely cause?
hard
A.The new drive has a different sector size (4K vs 512e).
B.The RAID controller is using some space for metadata.
✓ C.The replacement drive has a slightly smaller actual capacity than the original drives.
D.The RAID 5 array is degraded and needs a second drive to be replaced.
Why C: This question tests advanced RAID understanding. RAID 5 uses one drive's worth of capacity for parity, so three 1TB drives yield 2TB usable. The loss of 0.2TB suggests the replacement drive has slightly less capacity due to manufacturer differences or sector mapping.
Last reviewed: Jun 18, 2026
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.
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.