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XK0-006 Practice Question: A Linux administrator notices that the system’s…
A Linux administrator notices that the system’s disk I/O performance has degraded significantly. Running 'iostat -x 1' shows high %util values on /dev/sda, but low await. Which of the following is the most likely issue?
⚠ Common exam trap
CompTIA often tests the misconception that high %util always means slow I/O, but the trap here is that %util measures busy time, not latency; candidates overlook the low await and incorrectly assume hardware failure or cable issues.
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
✓
There are many concurrent I/O requests (high queue depth).
High %util with low await indicates that the device is busy processing many concurrent I/O requests, but each request completes quickly. This is characteristic of a high queue depth where the disk is saturated with parallel requests, not that individual requests are slow. The low await confirms that the disk itself is responding fast, so the bottleneck is the volume of simultaneous I/O, not latency per request.
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 filesystem is nearly full.
Why it's wrong here
A full filesystem produces write failures and ENOSPC errors, not sustained high %util with low await; iostat would show normal latency until writes fail. Capacity management is the right concern when df reports near-100% usage, but the stem's latency profile points to queueing, not space exhaustion.
- ✗
The disk cable is loose or faulty.
Why it's wrong here
High %util with low await indicates the device is busy servicing queued requests, typically from saturation or many small random I/Os, not a physical cabling fault. A loose cable would produce I/O errors, resets or the device dropping offline. Cable faults are tempting because they are physical, but they manifest as errors, not sustained utilisation.
- ✓
There are many concurrent I/O requests (high queue depth).
Why this is correct
High %util with low await indicates the device is saturated by request volume rather than slow individual operations. Many concurrent I/O requests queue up, keeping the disk busy; await stays low because each request completes quickly once serviced, so queue depth is the bottleneck.
- ✗
The disk is failing and needs replacement.
Why it's wrong here
Failing disks typically show rising await, retries and I/O errors in dmesg or SMART, not low await with high %util. Replacement is the correct action when SMART attributes or kernel logs confirm hardware degradation, but the metrics here indicate contention rather than media failure.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This XK0-006 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 XK0-006 exam.