vSAN read latency increase observed in vCenter UI cluster level graph

Products

• VMware vSAN

Issue/Introduction

vSAN read latency increase observed in vCenter UI cluster level graph for a short period of time.

The vSAN performance graphs at the Cluster --> Host --> Monitor --> vSAN --> Performance for the Physical adapters button show an increase in pNIC Packet Error Rate

 

Environment

vSAN OSA

Cause

Physical network issues are leading to high selective acknowledgement (SACK) rate. The need to retransmit the missing packets leads to latency proportionate to the SACK rate. 
No other network level errors are observed at the TCP layer, vSwitch, vmkernel port, or physical NICs.

 

Resolution

The issue was transient and self resolved.
Work with your physical network team or vendor to identify the cause of the transient problem.

Contact VMware by Broadcom support if assistance identifying the cause is required.