This EX200 practice question tests your understanding of configure local storage. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 database server experiences high disk I/O wait times. The administrator runs 'iostat -x 1' and sees that the avgqu-sz for /dev/sda is 25 and await is 200 ms. The disk is a single 7200 RPM SATA drive. Which action is most likely to improve performance?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Replace the drive with an SSD or add additional drives in RAID 10
The high avgqu-sz (25) and await (200 ms) indicate the single 7200 RPM SATA drive is saturated, as its maximum IOPS is typically around 75-100 random I/O operations per second. Replacing it with an SSD (which can handle thousands of IOPS) or adding drives in RAID 10 (which increases IOPS through parallelism) directly addresses the hardware bottleneck. No software tuning can overcome the physical limitations of a single spinning disk under heavy I/O load.
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.
✗
Increase the read-ahead buffer using blockdev --setra
Why it's wrong here
Increasing read-ahead may help sequential reads but not random I/O causing high await.
✗
Change the I/O scheduler from CFQ to noop
Why it's wrong here
While noop reduces scheduling overhead, the primary bottleneck is disk speed; changing scheduler may have minimal impact.
✗
Run 'fsck -f' on the filesystem to check for fragmentation
Why it's wrong here
fsck checks consistency, not fragmentation; ext4 is resistant to fragmentation.
✓
Replace the drive with an SSD or add additional drives in RAID 10
Why this is correct
SSD or RAID provides higher IOPS and lower latency, directly addressing the high await.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume software tuning (scheduler, read-ahead) can fix a hardware saturation issue, but Red Hat exams emphasize that when a single spinning disk is the bottleneck, only a hardware upgrade or RAID configuration will improve performance.
Detailed technical explanation
How to think about this question
A single 7200 RPM SATA drive has a rotational latency of ~4.17 ms and an average seek time of ~8-10 ms, limiting random IOPS to roughly 75-100. The avgqu-sz of 25 means the I/O queue is deeply backed up, and await of 200 ms indicates requests are spending most of their time waiting in the queue rather than being serviced. In contrast, an SSD has no moving parts, achieving 10,000-100,000+ IOPS, while RAID 10 stripes data across multiple drives to allow concurrent I/O operations, effectively multiplying the available IOPS.
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.
TExam Day Tips
→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 EX200 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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Configure local storage — This question tests Configure local storage — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Replace the drive with an SSD or add additional drives in RAID 10 — The high avgqu-sz (25) and await (200 ms) indicate the single 7200 RPM SATA drive is saturated, as its maximum IOPS is typically around 75-100 random I/O operations per second. Replacing it with an SSD (which can handle thousands of IOPS) or adding drives in RAID 10 (which increases IOPS through parallelism) directly addresses the hardware bottleneck. No software tuning can overcome the physical limitations of a single spinning disk under heavy I/O load.
What should I do if I get this EX200 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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