- A
Deploy a sidecar container that caches the data in an emptyDir volume.
Sidecar with caching can serve data from local disk, reducing Cloud Storage reads.
- B
Configure a Cloud SQL read replica for the data.
Why wrong: Cloud SQL is for relational data, not object storage.
- C
Increase the number of nodes in the cluster.
Why wrong: More nodes do not directly improve read performance per pod.
- D
Use a StatefulSet with a persistent volume claim to store the data.
Why wrong: Persistent volumes add complexity and cost; not optimal for caching.
Question 824 of 1,000
PCDOE Optimizing service performance Practice Question
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.
An application on GKE frequently reads the same data from a Cloud Storage bucket. The data changes rarely. Which solution will best improve read performance and reduce costs?
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
✓
Deploy a sidecar container that caches the data in an emptyDir volume.
Deploying a sidecar container with an emptyDir volume caches frequently accessed, rarely changing data locally within the pod. This reduces latency by avoiding repeated network calls to Cloud Storage and eliminates egress and operation costs for those reads. emptyDir volumes are ephemeral and tied to the pod's lifecycle, making them ideal for caching read-heavy, static data without incurring persistent storage costs.
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.
- ✓
Deploy a sidecar container that caches the data in an emptyDir volume.
Why this is correct
Sidecar with caching can serve data from local disk, reducing Cloud Storage reads.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Configure a Cloud SQL read replica for the data.
Why it's wrong here
Cloud SQL is for relational data, not object storage.
- ✗
Increase the number of nodes in the cluster.
Why it's wrong here
More nodes do not directly improve read performance per pod.
- ✗
Use a StatefulSet with a persistent volume claim to store the data.
Why it's wrong here
Persistent volumes add complexity and cost; not optimal for caching.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between caching (ephemeral, local, cost-effective) and persistent storage (StatefulSet/PVC) or scaling (adding nodes) — the trap here is assuming that increasing cluster resources or using persistent storage will improve read performance for static data, when a lightweight sidecar cache is the most efficient and cost-effective solution.
Detailed technical explanation
How to think about this question
Under the hood, emptyDir volumes are backed by the node's local ephemeral storage (typically a tmpfs filesystem if `medium: Memory` is set, or the node's disk), providing extremely low-latency access. The sidecar pattern allows the cache to be co-located with the application container, sharing the emptyDir volume via a volume mount. In practice, this approach is commonly used with tools like `gcsfuse` or a custom caching proxy to serve stale data until a background refresh, significantly reducing Cloud Storage API calls and associated costs.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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.
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FAQ
Questions learners often ask
What does this PCDOE question test?
Optimizing service performance — This question tests Optimizing service performance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Deploy a sidecar container that caches the data in an emptyDir volume. — Deploying a sidecar container with an emptyDir volume caches frequently accessed, rarely changing data locally within the pod. This reduces latency by avoiding repeated network calls to Cloud Storage and eliminates egress and operation costs for those reads. emptyDir volumes are ephemeral and tied to the pod's lifecycle, making them ideal for caching read-heavy, static data without incurring persistent storage costs.
What should I do if I get this PCDOE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jul 4, 2026
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