VCP-DCV Configure and Manage vSphere Storage Practice Question
An administrator notices that a VM with high I/O demands is experiencing performance issues because other VMs on the same datastore are consuming too many I/O operations. Which feature can be used to guarantee a minimum I/O share to this VM?
⚠ Common exam trap
VCP-DCV often tests the confusion between Storage DRS (which balances load) and SIOC (which guarantees shares), leading candidates to choose Storage DRS for I/O prioritization.
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
✓
Storage I/O Control shares
Storage I/O Control shares allow you to guarantee a minimum I/O share to a VM by assigning shares to its virtual disks. When contention occurs, ESXi enforces these shares to ensure the VM gets its fair share of I/O resources.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Multipathing policy
Why it's wrong here
Multipathing policy governs path selection and failover between storage adapters and arrays, not I/O scheduling between VMs sharing a datastore. It is tempting because multipathing addresses storage throughput and redundancy, and would be correct when a host loses a path to the LUN and needs failover.
- ✗
VM storage policy
Why it's wrong here
A VM storage policy defines placement and data services such as encryption or replication, not per-VM I/O shares. It is tempting because storage policies govern datastore behaviour, and would be correct when you need to enforce replication, tiering or encryption requirements on a VM's disks.
- ✗
Storage DRS
Why it's wrong here
Storage DRS balances datastore capacity and I/O load by migrating VMs between datastores; it reacts to imbalance rather than guaranteeing a minimum share to one VM. It is tempting because Storage DRS does address I/O contention, and would be correct when datastores are imbalanced and VMs should be relocated.
- ✓
Storage I/O Control shares
Why this is correct
Storage I/O Control shares guarantee a minimum I/O allocation to a virtual machine when the datastore becomes congested, directly addressing contention from other VMs. Shares are applied proportionally during contention, reserving throughput for the high-demand VM.
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Same concept, more angles
1 more way 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. An administrator is troubleshooting performance issues on a VMFS datastore hosting SQL Server VMs. Storage I/O Control (SIOC) is enabled, but the administrator notices that congestion is detected but no throttling is applied. What could be the reason?
medium- ✓ A.The SIOC congestion threshold is set too high
- B.The datastore is deduplicated
- C.SIOC is disabled on the datastore
- D.The host has exceeded the maximum number of concurrent I/Os
Why A: The SIOC congestion threshold is set too high, meaning that although congestion is detected, the threshold for applying throttling has not been reached. SIOC uses a congestion threshold (default 30ms) to determine when to throttle I/O. If the threshold is set too high, SIOC may detect congestion but not apply throttling because the latency has not exceeded the threshold. The administrator should lower the threshold to enable throttling.
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
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.