HCI VM Throughput Limited to Less Than 50 Mbps Despite 2 Gbps Configuration Issue Description
  

Muhammad Abid Lv3Posted 2026-Jul-02 20:05

A virtual machine running on Sangfor HCI was configured with a 2 Gbps network throughput, but the actual file transfer speed remained below 50 Mbps. The issue occurred during file transfers between the VM and another server, resulting in poor performance.

Product & Version
Product: Sangfor HCI
Version: (Please replace with your HCI version, e.g., HCI 6.10.0)
VM OS: Windows Server (Replace with your operating system if different)
Root Cause

After checking the environment, the following factors were identified as possible causes:

The VM network adapter was not negotiating the expected link speed.
Physical switch port speed/duplex configuration was incorrect.
High storage or network utilization affected VM performance.
MTU mismatch between network devices.
Bandwidth limitations or QoS policies on the virtual switch or physical network.
Troubleshooting Steps
Verified VM network adapter settings.
Checked physical NIC and switch port speed/duplex status.
Monitored CPU, memory, storage latency, and network utilization on the HCI host.
Tested connectivity using iperf to measure actual network throughput.
Reviewed QoS and bandwidth limitation policies.
Verified MTU configuration across the network path.
Updated the VM network driver and restarted the VM.
Solution
Corrected the switch port speed and duplex settings.
Removed unnecessary bandwidth restrictions.
Updated the VM network adapter driver.
Ensured the VM was connected to the correct virtual switch.
Confirmed consistent MTU settings across all network devices.
Verification

After applying the above changes:
VM network throughput increased significantly.
File transfer speed improved from less than 50 Mbps to the expected performance based on the network environment.
Multiple transfer tests confirmed stable and consistent performance.
Lessons Learned

When VM throughput is much lower than the configured bandwidth, always verify:

VM NIC configuration
Physical switch port settings
Storage performance
QoS or bandwidth limits
MTU consistency
Driver compatibility

Has anyone else experienced similar throughput issues on Sangfor HCI? I'd be interested to hear what was causing it in your environment and how you resolved it.

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Muhammad Shiraz Lv2Posted 2026-Jul-03 12:52
  
Thanks for sharing
Humayun Ahmed Lv4Posted 2026-Jul-03 11:58
  
Thanks to share!