NCP-MCI-6.10 · Question #96
An administrator is executing a storage performance test between two Microsoft Windows VMs. The first VM was deployed by using a template, while the second one was created from scratch. Results show…
The correct answer is C. Compare vDisk bus type between VMs. The dramatic IOPS difference (8,000 vs. 500–800) between the two VMs is a classic symptom of mismatched vDisk bus types. A VM deployed from a template likely inherited a high-performance VirtIO (paravirtualized) SCSI controller, which on AHV can deliver tens of thousands of…
Question
An administrator is executing a storage performance test between two Microsoft Windows VMs. The first VM was deployed by using a template, while the second one was created from scratch. Results show that VMs have very different metrics when using the same performance test. The first VM reaches 8000 IOPS, while the second struggles reaching 500/800 IOPS. Currently the AHV cluster is not under pressure. How can the administrator determine why these results were produced?
Options
- AVerify both VMs have installed Nutanix Guest Tools.
- BEnable AHV Turbo on the second VM.
- CCompare vDisk bus type between VMs.
- DCheck number of VCPUs assigned to VMs
How the community answered
(42 responses)- A2% (1)
- B5% (2)
- C83% (35)
- D10% (4)
Explanation
The dramatic IOPS difference (8,000 vs. 500–800) between the two VMs is a classic symptom of mismatched vDisk bus types. A VM deployed from a template likely inherited a high-performance VirtIO (paravirtualized) SCSI controller, which on AHV can deliver tens of thousands of IOPS. A VM created from scratch in some workflows defaults to an emulated IDE or legacy SCSI controller, which is significantly slower and typically caps out around 500–800 IOPS because it relies on slower emulation rather than paravirtualized drivers. Nutanix Guest Tools (A) handles guest-level features but not vDisk bus type. AHV Turbo (B) helps CPU-bound workloads, not storage. vCPU count (D) would affect CPU-bound performance, not raw storage IOPS at this scale.
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