2V0-620 · Question #55
A Fault Tolerance (FT) virtual machine with four vCPUs is experiencing high latency when performing ICMP and Application tests. What are three potential causes that may be attributing to this…
The correct answer is A. The FT network has insufficient bandwidth and is running on a 1GB Link. B. The FT network is on a particularly high latency link. C. The FT network has been configured with Network I/O Control. High latency in a 4-vCPU FT VM can be caused by insufficient FT logging bandwidth, a high-latency logging link, or Network I/O Control policies throttling the FT logging stream.
Question
A Fault Tolerance (FT) virtual machine with four vCPUs is experiencing high latency when performing ICMP and Application tests. What are three potential causes that may be attributing to this latency? (Choose three.)
Options
- AThe FT network has insufficient bandwidth and is running on a 1GB Link.
- BThe FT network is on a particularly high latency link.
- CThe FT network has been configured with Network I/O Control.
- DThe FT virtual machine is running an e1000 network adapter.
- EThe FT virtual machine is running on poor performing network-based storage.
How the community answered
(55 responses)- A58% (32)
- D29% (16)
- E13% (7)
Why each option
High latency in a 4-vCPU FT VM can be caused by insufficient FT logging bandwidth, a high-latency logging link, or Network I/O Control policies throttling the FT logging stream.
A 4-vCPU FT VM generates substantially more FT logging traffic than a 1-vCPU VM, and a 1GB link may become saturated, causing queuing delays that manifest as increased latency in ICMP and application tests.
The FT logging channel transmits continuous state updates between the primary and secondary VMs - a high-latency physical link in this path directly increases synchronization delay and contributes to observable application latency.
Network I/O Control can impose bandwidth limits or shares on the FT traffic type, which may throttle the FT logging stream and introduce latency when the FT network competes with other workloads for bandwidth.
The virtual NIC type (e1000) affects the guest's data-plane network performance but is unrelated to FT logging channel latency, which operates on a separate VMkernel path.
Poor network-based storage performance affects disk I/O latency within the VM but does not directly cause FT logging network latency as measured by ICMP or application-level tests.
Concept tested: vSphere Fault Tolerance logging network latency and bandwidth
Source: https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.avail.doc/GUID-C65F220E-F85F-4EA2-B0BE-F8CDB4B5FEFD.html
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