VCP-DCV vSphere Performance and Scaling Practice Question
This VCP-DCV practice question tests your understanding of vsphere performance and scaling. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
Your company has a vSphere 7 environment with four clusters: Cluster-A (production VMs), Cluster-B (development), Cluster-C (database), and Cluster-D (VDI). Each cluster has 8 hosts with 256 GB RAM and dual 12-core CPUs (hyper-threading enabled). The environment uses vSAN for storage, with all-flash disk groups (1 NVMe cache + 4 SATA SSD capacity per host). You are the lead administrator. Recently, users in the VDI cluster (Cluster-D) report slow logins and application responsiveness during peak hours (9-11 AM). You examine the vSAN performance metrics and see that the cache hit ratio during peak hours drops to 60%, and the average read latency is 15 ms. The VMs are thin provisioned and use a storage policy with RAID-1 mirroring (FTT=1). The cluster has DRS enabled with default migration threshold. What should you do to improve VDI performance without disruptive changes?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a second NVMe cache device or upgrade to higher-endurance NVMe drives in each host to increase cache size.
The VDI cluster's poor performance is caused by a low cache hit ratio (60%) and high read latency (15 ms) during peak hours. Adding a second NVMe cache device or upgrading to higher-endurance NVMe drives increases the cache size, allowing more read data to be served from the fast cache layer rather than the slower SATA SSD capacity tier. This directly improves the cache hit ratio and reduces read latency without requiring disruptive changes to the cluster.
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.
✗
Disable DRS for the VDI cluster to prevent VMs from migrating during peak hours.
Why it's wrong here
Disabling DRS may cause imbalance, not improve cache performance.
✗
Change the VM storage policy to RAID-5 erasure coding to reduce capacity overhead, freeing cache for reads.
Why it's wrong here
RAID-5 does not directly improve read cache hit ratio and may increase write overhead.
✗
Add more SATA SSD capacity disks to each host to increase overall storage performance.
Why it's wrong here
More capacity disks increase throughput but not cache hit ratio.
✓
Add a second NVMe cache device or upgrade to higher-endurance NVMe drives in each host to increase cache size.
Why this is correct
Larger cache improves hit ratio and reduces read latency.
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 often confuse capacity (adding more SATA SSDs) with cache performance, or mistakenly think changing the storage policy to RAID-5 will improve read latency, when the real fix is expanding the NVMe cache layer to handle the VDI working set.
Detailed technical explanation
How to think about this question
In vSAN, the cache tier (NVMe) acts as a read cache and write buffer; a cache hit ratio below 90% indicates the cache is too small for the working set. For VDI workloads with high I/O concurrency, increasing cache size or using higher-endurance NVMe drives (e.g., Intel Optane) can dramatically reduce read latency by serving more I/Os from the cache. The default vSAN storage policy with RAID-1 mirroring (FTT=1) consumes 2x capacity, but the issue here is cache sizing, not capacity efficiency.
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 VCP-DCV 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.
vSphere Performance and Scaling — This question tests vSphere Performance and Scaling — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a second NVMe cache device or upgrade to higher-endurance NVMe drives in each host to increase cache size. — The VDI cluster's poor performance is caused by a low cache hit ratio (60%) and high read latency (15 ms) during peak hours. Adding a second NVMe cache device or upgrading to higher-endurance NVMe drives increases the cache size, allowing more read data to be served from the fast cache layer rather than the slower SATA SSD capacity tier. This directly improves the cache hit ratio and reduces read latency without requiring disruptive changes to the cluster.
What should I do if I get this VCP-DCV 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.
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Question Discussion
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