VCP-DCV Configure and Manage vSphere Storage Practice Question
A financial services company has a vSAN cluster composed of 4 hosts, each with 8 disk groups (1 SSD cache and 6 HDD capacity per group). The cluster runs a mix of VMs, including a critical trading application VM that requires low latency. The administrator notices that the trading VM experiences intermittent performance degradation during market hours. vSAN performance monitoring shows high I/O latency for the VM's objects. The storage policy for this VM is set to RAID-1 (Mirroring) with Primary Failures to Tolerate (PFTT)=1 and Object Space Reservation=100%. The cluster has a disk capacity of 80% used. The administrator also observes that the vSAN cluster is configured with a single fault domain. Which action should the administrator take to improve the trading VM's performance?
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
✓
Reduce the number of disk groups per host to 2, using larger SSDs for cache, to reduce cache contention.
The performance degradation is likely due to cache contention. With 8 disk groups per host, each group has its own SSD cache, and the high number of cache devices can lead to contention and increased latency. Reducing the number of disk groups to 2 with larger SSDs consolidates cache, reducing contention and improving I/O performance. Option B is incorrect because adding more hosts does not reduce cache contention per host; it may even increase east-west traffic. Option C is incorrect because changing to PFTT=2 with RAID-5/6 increases overhead and requires more capacity, worsening performance. Option D is incorrect because deduplication and compression add CPU overhead and increase latency, not reduce it.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Reduce the number of disk groups per host to 2, using larger SSDs for cache, to reduce cache contention.
Why this is correct
Correct: With 8 disk groups per host, there are many SSDs competing; reducing groups alleviates cache contention and improves latency.
- ✗
Add two more hosts to the cluster and redistribute the disk groups.
Why it's wrong here
Incorrect: Adding hosts may help capacity but does not directly address the cache contention issue on existing hosts.
- ✗
Change the storage policy to PFTT=2 and Failure Tolerance Method=RAID-5/6 to reduce the number of replicas.
Why it's wrong here
Incorrect: RAID-5/6 with PFTT=2 would require more components and add CPU overhead, likely increasing latency.
- ✗
Enable deduplication and compression on the vSAN datastore to reduce capacity usage and I/O.
Why it's wrong here
Incorrect: Deduplication and compression increase CPU usage and can increase latency, not reduce it.
Quick reference
RAID Level Comparison
| RAID Level | Min Disks | Fault Tolerance | Read | Write | Usable Capacity |
|---|---|---|---|---|---|
| RAID 0 | 2 | None | Excellent | Excellent | 100% |
| RAID 1 | 2 | 1 disk | Good | Moderate | 50% |
| RAID 5 | 3 | 1 disk | Good | Moderate | 67–94% |
| RAID 6 | 4 | 2 disks | Good | Lower | 50–88% |
| RAID 10 | 4 | 1 disk per mirror | Excellent | Good | 50% |
RAID is not a backup strategy — it protects against disk failure but not against accidental deletion, ransomware, or site-level events.
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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.