CV0-002 · Question #116
A host with 30 VMs has 64GB of RAM, four quad-core CPUs, four 1-gigabit NICs and is connected to a NAS that provides NFS volumes. The hosted VMs are reporting slow performance. From the information gi
The correct answer is D. Insufficient network capacity. With 30 virtual machines, four 1-gigabit NICs shared for all network and NAS traffic represent a significant bottleneck, making insufficient network capacity the most probable cause of slow performance.
Question
A host with 30 VMs has 64GB of RAM, four quad-core CPUs, four 1-gigabit NICs and is connected to a NAS that provides NFS volumes. The hosted VMs are reporting slow performance. From the information given, which of the following is the MOST likely cause of the slow performance?
Options
- AInsufficient NAS capacity
- BThe server is using 110V instead of 220V
- COne hard drive has failed in the RAID 5
- DInsufficient network capacity
How the community answered
(50 responses)- A2% (1)
- B18% (9)
- C10% (5)
- D70% (35)
Why each option
With 30 virtual machines, four 1-gigabit NICs shared for all network and NAS traffic represent a significant bottleneck, making insufficient network capacity the most probable cause of slow performance.
While NAS capacity could be an issue, 'insufficient NAS capacity' typically refers to available storage space, not necessarily I/O performance which would relate more to network or disk I/O on the NAS itself.
The server's power voltage (110V vs 220V) affects power efficiency and delivery but generally does not directly cause slow performance unless the server is underpowered, which would likely manifest as reboots or failures.
A failed hard drive in a RAID 5 array would impact storage performance on the RAID array itself, but the question indicates VMs are connected to a NAS via NFS, meaning the host server's local drives are likely not the primary storage for the VMs.
Each 1-gigabit NIC provides approximately 125 MB/s throughput, and with 30 VMs sharing four such NICs for both internal VM-to-VM communication and external NAS (NFS) access, the total bandwidth of 4 Gbps (500 MB/s) is easily overwhelmed. This bottleneck is exacerbated when VMs frequently access storage over NFS, as all storage I/O also traverses these NICs, leading to network saturation and slow performance.
Concept tested: Virtualization resource bottlenecks, network throughput
Source: https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/best-practices/run-hyper-v-on-windows-server
Topics
Community Discussion
No community discussion yet for this question.