PK0-005 Practice Question: Basics of IT Infrastructure and IT Project Management
A large organization is deploying a new ERP system. The infrastructure team provisions a cluster of virtual machines for the application and a separate database server. During load testing with typical user loads, the database server shows high I/O wait times. The storage administrator confirms that the storage array has sufficient capacity and the disks are healthy. The hypervisor shows no CPU or memory pressure. Which of the following is the most likely cause of the high I/O wait?
⚠ Common exam trap
Many candidates assume high I/O wait always means a disk hardware failure or capacity issue, but the question explicitly states disks are healthy and capacity is sufficient, steering the answer toward a RAID-level misconfiguration that causes excessive write overhead.
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
✓
Misconfigured RAID level, such as using RAID 5 for a write-intensive workload.
RAID 5 uses parity-based striping, which incurs a write penalty (each write requires four I/O operations: read old data, read old parity, write new data, write new parity). For a write-intensive workload like an ERP database, this overhead causes high I/O wait times even when disks are healthy and capacity is sufficient. The correct answer is C because the misconfigured RAID level directly explains the observed symptom.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Network bandwidth saturation between the database and application servers.
Why it's wrong here
Network saturation would inflate latency and throughput between tiers, not produce I/O wait on the database server itself. It is tempting because bandwidth constraints genuinely degrade database performance, and would be the cause if interface counters showed saturation. Here, storage capacity and disk health are confirmed, pointing to storage latency.
- ✗
Insufficient memory on the database server causing paging.
Why it's wrong here
The hypervisor reports no memory pressure, so the database server is not paging; paging would also surface as memory contention rather than isolated I/O wait. It is tempting because insufficient memory genuinely causes paging and disk thrashing, and would be the cause if memory metrics were exhausted.
- ✓
Misconfigured RAID level, such as using RAID 5 for a write-intensive workload.
Why this is correct
RAID 5's parity write penalty makes it poor for write-intensive database workloads, producing high I/O wait despite healthy disks and spare capacity. CPU, memory and capacity are already excluded, so the RAID level is the likely cause.
- ✗
CPU overutilization on the database server.
Why it's wrong here
The hypervisor shows no CPU pressure, so CPU overutilization is excluded; CPU contention would also manifest as high CPU ready time, not I/O wait. It is tempting because CPU starvation genuinely stalls database queries, and would be the cause if processor utilisation were saturated.
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.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PK0-005 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 PK0-005 exam.