VCP-DCV vSphere Performance and Scaling Practice Question
An administrator is configuring storage performance for a vSphere cluster that runs a mix of I/O-intensive databases and general-purpose VMs. The storage array is capable of providing high IOPS, but the administrator wants to ensure that the database VMs receive preferential treatment during periods of storage contention. The administrator has created a datastore cluster and enabled Storage DRS. Which additional configuration should be applied to meet this requirement?
⚠ Common exam trap
Many candidates confuse Storage DRS, which handles initial placement and migration, with Storage I/O Control, which manages runtime I/O prioritization during contention.
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
✓
Enable Storage I/O Control on the datastore cluster and set shares on the database VMs' virtual disks.
Storage I/O Control (SIOC) is the correct solution because it enables per-virtual-disk share-based prioritization when a datastore becomes congested. By assigning higher shares to database VMs, they receive a larger portion of I/O resources during contention, ensuring preferential treatment without isolating storage or resorting to limits.
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 separate datastore for the database VMs and place it on a dedicated LUN.
Why it's wrong here
Isolating database VMs on a dedicated LUN can reduce contention from other VMs, but it does not provide a mechanism for preferential treatment when multiple database VMs compete on the same LUN. It also may not be feasible with the existing storage configuration. This approach addresses isolation, not prioritization during contention.
- ✗
Configure Storage DRS to use the 'I/O latency' threshold and set it to a low value.
Why it's wrong here
Storage DRS uses I/O latency thresholds to trigger migrations for load balancing, but it does not provide per-VM I/O prioritization. A low threshold may cause more frequent migrations, which can be disruptive, but it does not ensure that database VMs get preferential I/O treatment during contention. Storage DRS is about placement, not runtime prioritization.
- ✓
Enable Storage I/O Control on the datastore cluster and set shares on the database VMs' virtual disks.
Why this is correct
Storage I/O Control (SIOC) allows you to set shares on virtual disks, which determines their relative priority for I/O resources when the datastore experiences contention. By enabling SIOC and assigning higher shares to database VMs, they receive preferential treatment during congestion. This directly addresses the requirement for preferential I/O treatment during contention.
- ✗
Set a storage limit on the general-purpose VMs to restrict their I/O usage.
Why it's wrong here
Storage limits can restrict the maximum IOPS a VM can consume, but they are not a prioritization mechanism. They can prevent a VM from overwhelming storage, but they do not give preference to database VMs. Limits are applied per virtual disk and can cause throttling, but they do not dynamically allocate resources based on shares or priority during contention.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official VMware exam blueprint
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