DRS Migration Threshold: How to Reduce CPU Ready Time
A large e-commerce company has a vSphere cluster with 16 hosts, each with 2 sockets of 10 cores (HT enabled) and 512 GB RAM. They run a mix of web and database VMs. During the holiday season, some VMs experience high CPU ready time, especially the database VMs. DRS is set to Fully Automated and migration thresholds are at default. The administrator notices that the cluster's CPU utilization averages at 60%, but some hosts are at 90% while others are at 30%. The VMs with high ready time are all on the highly utilized hosts. To resolve this, the administrator considers several options. Which action will most effectively balance CPU load and reduce ready time for the database VMs?
Quick Answer
Decreasing the DRS migration threshold from 3 to 1 is correct because the cluster's data shows a real, ongoing imbalance rather than a brief spike, with some hosts sitting at 90% utilization while others sit at 30%, and the database VMs experiencing high ready time specifically on the overloaded hosts. The migration threshold controls how large that imbalance needs to get before DRS actually acts on its recommendations, and a more conservative default setting can leave meaningful imbalances like this one unaddressed for longer than the workload can tolerate, especially during a demand surge like the holiday season. Moving the threshold to its most aggressive setting means DRS will respond to smaller imbalances and migrate VMs more proactively, redistributing load off the hot hosts and onto the underutilized ones, which directly reduces the CPU contention driving up ready time on the database VMs. This differs from raising resource pool shares, which only changes prioritization within a single host's contention and does nothing to physically move VMs to less busy hardware, and different from loosening the threshold further, which would only allow the imbalance to persist longer. It is also unrelated to VM Monitoring, an HA fault-detection feature with no bearing on load balancing. When cluster utilization is unevenly distributed across hosts and ready time is concentrated on the busiest ones, a more aggressive DRS threshold, not per-VM configuration changes, is the lever built to fix it.
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
✓
Decrease the DRS migration threshold from 3 to 1 to make it more aggressive.
Decreasing the DRS migration threshold from 3 to 1 makes DRS more aggressive, triggering migrations even for small imbalances. This will redistribute VMs from highly utilized hosts to underutilized hosts, reducing CPU ready time for database VMs. Option A (resource pool with higher shares) does not cause migrations; it only prioritizes CPU allocation during contention on the same host. Option B (increasing threshold to 5) makes DRS less aggressive, worsening the imbalance. Option C (VM Monitoring) is an HA feature for fault detection, not load balancing.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create a resource pool for database VMs and set a higher CPU share value.
Why it's wrong here
Shares only affect relative entitlement on a single host; they do not trigger migrations to balance load across hosts.
- ✗
Increase the DRS migration threshold from 3 to 5 to reduce unnecessary migrations.
Why it's wrong here
A higher threshold makes DRS less proactive, allowing imbalances to persist and worsening ready time.
- ✗
Enable 'VM Monitoring' in the HA cluster settings.
Why it's wrong here
VM Monitoring restarts unresponsive VMs but does not balance CPU load.
- ✓
Decrease the DRS migration threshold from 3 to 1 to make it more aggressive.
Why this is correct
A lower threshold triggers migrations even for minor load imbalances, helping to spread VMs and reduce ready time on hot hosts.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 498 original VCP-DCV practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on VCP-DCV
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A vSphere cluster with 3 ESXi hosts (each with 2 sockets, 8 cores per socket, hyperthreading enabled, and 256 GB RAM) runs a set of web server VMs. The cluster is configured with DRS enabled and a migration threshold of 3 (conservative). The administrator notices that one host has consistently high CPU ready time (average 15%) while the other two hosts have ready time below 2%. The host with high ready time has 10 VMs, while the others have 6 each. CPU utilization on the busy host is 80%, while on the other hosts it is 40%. What should the administrator do to improve the situation with minimal disruption?
easy- A.Disable Hyper-Threading on all hosts to reduce vCPU contention.
- B.Manually migrate some VMs from the overloaded host to the other hosts using vMotion.
- C.Add a fourth host to the cluster.
- ✓ D.Increase the DRS migration threshold to a more aggressive value (e.g., 4 or 5).
Why D: The cluster is unbalanced because DRS is not migrating VMs aggressively enough. Increasing the DRS migration threshold to a more aggressive level will allow DRS to move VMs from the overloaded host to the underutilized hosts. Option D is the best immediate step. Option A would increase overhead and is not best practice. Option B would be effective but requires manual intervention and may not be the simplest. Option C would add capacity but is a longer-term solution.
Variation 2. A vSphere cluster with DRS enabled is experiencing an imbalance in resource utilization across hosts. DRS is set to 'Manual' mode. What action should the administrator take to resolve the imbalance?
easy- A.Change DRS to 'Fully Automated' mode.
- ✓ B.Manually migrate VMs using vMotion.
- C.Enable HA admission control.
- D.Increase the DRS migration threshold.
Why B: In Manual mode, DRS only provides recommendations; the administrator must manually migrate VMs using vMotion. Option B is correct. Option A would automate future migrations but does not resolve current imbalance. Option C changes threshold but won't act immediately. Option D is unrelated.
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.