VSAN High latency over 5ms found on multiple clusters

Products

• VMware vSAN

Issue/Introduction

There are several VMs experiencing high latency on multiple vSAN cluster on specific hosts.  These VMs are SQL servers and Web Servers that are impacted and show latency in the live performance graphs in vCenter via vSAN Cluster > Monitor > vSAN > Performance.

Environment

VMware vSAN (All Versions)

Cause

There are packet drops on the network.

Resolution

Review the local physical network switches.  As multiple clusters are similarly impacted, the common denominator would be the network transport drops impacting VM performance.  The hosts see vSwitch Port Drops of 0.003%. That doesn’t sound like much, but these should be 0% drops, otherwise something is failing on the network.  Plus, for the vSAN Hyperconverged Infrastructure (HCI), it is recommended no more than 0.001% TCP packet issues on the physical network infrastructure.  Physical NIC and HCI requirements can be found in the following doc.

Physical NIC Requirements