Quick Answer
The correct answer is that data remains fully available, though performance may degrade. This is because RAID 5 uses block-level striping with distributed parity across all disks; with three disks, the parity information on the two surviving drives allows the system to reconstruct the missing data on the fly, so no data is lost immediately after a single disk failure. On the CompTIA ITF+ FC0-U61 exam, this scenario tests your understanding of fault tolerance versus performance trade-offs—a common trap is assuming any disk failure causes data loss, but RAID 5 specifically tolerates one failure. Remember the memory tip: “RAID 5 keeps data alive with one drive’s dive.”
This FC0-U61 practice question tests your understanding of infrastructure. 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 company has a server that hosts a critical database. The server uses RAID 5 with three disks. One disk fails. What is the immediate impact on data availability?
Data is available only after replacing the disk
Why wrong: Data is available immediately.
The server will shut down
Why wrong: RAID 5 remains operational.
All data on the array is lost
Why wrong: RAID 5 can survive one disk failure.
Data is still available, but performance may degrade
RAID 5 uses parity; with one disk missing, reads are slower.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Data is still available, but performance may degrade
RAID 5 uses block-level striping with distributed parity. With three disks, the array can tolerate a single disk failure without data loss because the parity information on the remaining two disks can reconstruct the missing data on the fly. Therefore, data remains fully available immediately after one disk fails, though read and write performance may degrade due to the overhead of parity calculation and reconstruction.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Data is available only after replacing the disk
Why it's wrong here
Data is available immediately.
The server will shut down
Why it's wrong here
RAID 5 remains operational.
All data on the array is lost
Why it's wrong here
RAID 5 can survive one disk failure.
Data is still available, but performance may degrade
Why this is correct
RAID 5 uses parity; with one disk missing, reads are slower.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse RAID 5 with RAID 0, assuming any disk failure causes total data loss, or they mistakenly think the array becomes completely unavailable until the disk is replaced.
Detailed technical explanation
In RAID 5, parity is distributed across all disks, so when one disk fails, the controller uses the parity blocks on the surviving disks to XOR-reconstruct the missing data for each read request. Write operations in degraded mode require reading the old data and parity, then writing the new data and recalculated parity, increasing I/O latency. In a real-world scenario, a failed disk in a RAID 5 array triggers a rebuild process that can take hours, during which performance is reduced and the array is vulnerable to a second failure.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the FC0-U61 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.
What to study next
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FAQ
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: Data is still available, but performance may degrade — RAID 5 uses block-level striping with distributed parity. With three disks, the array can tolerate a single disk failure without data loss because the parity information on the remaining two disks can reconstruct the missing data on the fly. Therefore, data remains fully available immediately after one disk fails, though read and write performance may degrade due to the overhead of parity calculation and reconstruction.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This FC0-U61 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 FC0-U61 exam.
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