High pNic error rate detected on Mellanox network adapter.

Products

• VMware vSphere ESXi

Issue/Introduction

• Random ESXi hosts have the following alert: High pNic error rate detected on vmnic.
• Issue is observed in hosts having Mellanox adapters. 
• However, the environment is not facing any impact due to this alert. 
• vCenter Server displays a Warning or Critical alarm: High pNic error rate detected. Check the host's vSAN performance view for details.
• The below command may be executed to show incrementing Receive missed errors.
• esxcli network nic stats get -n vmnicX
• The errors may appear randomly or during periods of bursty traffic.

.

Environment

VMware ESXi 8.x

VMware vSAN 8.x

Cause

.Mellanox network drivers may report high "receive missed" or "out of buffer" errors during transient traffic spikes or micro-bursts. In many environments, these errors are historical or do not correlate with actual packet loss affecting vSAN performance. The default vSAN thresholds (0.1% Warning, 1% Critical) are often too sensitive for these specific hardware configurations.

Resolution

If there is no impact, you can proceed to suppress the alert by changing the thresholds as explained in the below article:

https://techdocs.broadcom.com/us/en/vmware-cis/vsan/vsan/8-0/vsan-monitoring/monitor-the-vsan-cluster/using-the-vsan-default-alarms/view-vsan-network-alarms.html

The below are the recommended VSAN threshold values:
1. Warning: 1% (default: 0.1%)
2. Critical: 3% (default: 1%)

1. Navigate to the affected ESXi host in the vSphere Client.
2. Select the Monitor tab.
3. Under vSAN, select Performance.
4. Select Physical Adapters and choose the affected NIC (e.g., vmnic4).
5. Click Threshold settings.
6. Update the following values:
   • Warning: 1% (default is 0.1%)
   • Critical: 3% (default is 1%)
7. Click Save.
8. Navigate to Monitor > Alarms > Triggered Alarms and click Reset to Green for the affected host.

If the alerts continue despite the change, please open a support case with Broadcom Support. For more information, see Creating and managing Broadcom support cases.