VCP-DCV vSphere Performance and Scaling Practice Question
A company runs a four-node vSphere 7 cluster with all-flash storage and 25GbE networking. The cluster hosts 50 VMs, including a critical database VM with 16 vCPUs and 64 GB memory. The database VM's performance has degraded over the past week. vCenter reports high CPU ready time (average 15%) for the database VM, while other VMs show less than 2%. CPU utilization on the host is 70%. The database VM is configured with CPU affinity pinned to cores 0-15 on a dual-socket host with 16 cores per socket (32 total). The administrator also notices that the database VM's CPU co-stop counter is high. What should the administrator do to improve performance?
⚠ Common exam trap
Watch out — candidates often assume high ready time means the host is overloaded and choose to migrate or add vCPUs, overlooking that CPU affinity artificially constrains the scheduler and causes co-stop delays.
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
✓
Remove the CPU affinity setting for the database VM.
The high CPU ready time (15%) and elevated co-stop counter indicate that the database VM is suffering from contention due to CPU affinity pinning to cores 0-15. On a dual-socket host with 16 cores per socket, pinning to cores 0-15 restricts the VM to a single NUMA node, preventing the scheduler from load-balancing across both sockets. Removing the affinity allows the ESXi scheduler to distribute vCPUs across all 32 cores, reducing co-scheduling overhead and ready time.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Migrate the database VM to a host with fewer VMs.
Why it's wrong here
While it might help, the issue is likely NUMA-related and migration is a temporary fix.
- ✗
Enable CPU hot-add for the database VM.
Why it's wrong here
CPU hot-add does not address ready time and co-stop.
- ✓
Remove the CPU affinity setting for the database VM.
Why this is correct
Allows the scheduler to balance across NUMA nodes, reducing ready time and co-stop.
- ✗
Increase the number of vCPUs for the database VM to 32.
Why it's wrong here
More vCPUs would increase contention and likely worsen performance.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This VCP-DCV practice question is part of Courseiva's free VMware 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 VCP-DCV exam.