Quick Answer
The answer is to use SSD persistent disks instead of standard persistent disks. This is correct because SSD persistent disks rely on flash memory, which delivers consistent, low-latency I/O performance, while standard persistent disks use spinning magnetic media that can cause periodic latency spikes under sustained or bursty workloads. On the Google Professional Cloud DevOps Engineer exam, this scenario tests your understanding of storage performance characteristics for stateful workloads, often appearing as a trap where candidates might mistakenly suggest increasing disk size or adding caching. The key distinction is that standard disks suffer from rotational latency and queue depth fluctuations, whereas SSDs provide predictable IOPS. A useful memory tip: think of standard disks as a vinyl record—spinning and prone to skips under load—while SSDs are like a solid-state drive in a gaming rig, delivering smooth, spike-free performance.
This PCDOE practice question tests your understanding of optimizing service performance. 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 company runs a stateful workload on Compute Engine VMs with persistent disks. They observe that disk I/O latency spikes periodically. The workload is sensitive to latency. What should they do to improve performance?
Increase the size of the persistent disk.
Why wrong: Size does not directly affect latency.
Migrate to local SSDs for better performance.
Why wrong: Local SSDs are ephemeral and not suitable for stateful workloads.
Use SSD persistent disks instead of standard persistent disks.
SSD offers lower latency and higher IOPS.
Configure a snapshot schedule to offload I/O.
Why wrong: Snapshots do not improve I/O performance.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use SSD persistent disks instead of standard persistent disks.
Option C is correct because SSD persistent disks provide consistent, low-latency I/O performance compared to standard persistent disks, which use spinning media and can exhibit periodic latency spikes under sustained load. For latency-sensitive stateful workloads, SSD persistent disks offer predictable IOPS and throughput, directly addressing the periodic spikes observed.
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.
Increase the size of the persistent disk.
Why it's wrong here
Size does not directly affect latency.
Migrate to local SSDs for better performance.
Why it's wrong here
Local SSDs are ephemeral and not suitable for stateful workloads.
Use SSD persistent disks instead of standard persistent disks.
Why this is correct
SSD offers lower latency and higher IOPS.
Related concept
Read the scenario before looking for a memorised answer.
Configure a snapshot schedule to offload I/O.
Why it's wrong here
Snapshots do not improve I/O performance.
Common exam traps
Google Cloud often tests the misconception that increasing disk size or using local SSDs is the universal fix for latency, but the trap here is failing to recognize that the workload is stateful and requires persistent storage, making local SSDs inappropriate despite their performance.
Detailed technical explanation
Persistent disks in Google Cloud are network-attached block storage, and standard persistent disks use HDD-based storage with a shared backend, leading to variable latency under contention. SSD persistent disks use solid-state storage with dedicated IOPS provisioning (e.g., 30 IOPS/GB for pd-ssd vs. 0.75 IOPS/GB for pd-standard), ensuring consistent sub-10ms latency. In contrast, local SSDs are physically attached to the host server, offering even lower latency (microseconds) but with the trade-off of non-persistence, which violates stateful workload requirements.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Optimizing service performance — This question tests Optimizing service performance — Read the scenario before looking for a memorised answer..
The correct answer is: Use SSD persistent disks instead of standard persistent disks. — Option C is correct because SSD persistent disks provide consistent, low-latency I/O performance compared to standard persistent disks, which use spinning media and can exhibit periodic latency spikes under sustained load. For latency-sensitive stateful workloads, SSD persistent disks offer predictable IOPS and throughput, directly addressing the periodic spikes observed.
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 30, 2026
This PCDOE practice question is part of Courseiva's free Google Cloud 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 PCDOE exam.
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