Alarm: High pNIC Error rate detected

Products

• VMware vSphere ESXi

Issue/Introduction

• From within vCenter the following error is displayed: "High pNIC Error rate detected"
• From ESX, the following output shows the missed errors are caused by buffer overflow.
  
  /usr/lib/vmware/vm-support/bin/nicinfo.sh | grep -E " Receive missed errors|outOfBuffer"
Receive missed errors: 142775
outOfBuffer: 142775
Receive missed errors: 109406
outOfBuffer: 109406

Environment

VMware ESX

Resolution

NOTE: Increasing NIC buffer size may increase latency. Consult with hardware vendor before making changes.

1. To mitigate buffer over issues the buffer on the NIC can be increased.
2. Find the maximum supported buffer size for the given NIC. Replace vmnicX with the device number, e.g. vmnic0.
   

   esxcli network nic ring current get -n vmnic[X]

3. Verify the Current Ring Size and the Supported Maximum Ring Size.
   

    Current Ring Size:
   RingInfo:
      RX: 1023
      RX Mini: 0
      RX Jumbo: 0
      TX: 1023

     Supported Maximum Ring Size:
  RingInfo:
      Max RX: 8192
      Max RX Mini: 0
      Max RX Jumbo: 0
      Max TX: 8192
   
   

4. Set new buffer size. Ensure the value is less than or equal to maximum value identified in the previous step. To apply the change, use

   esxcli network nic ring current set -r [Value] -n vmnicX