After patching hosts, once hosts come back up connectivity errors are seen and vSAN has degraded.

Products

• VMware vSAN

Issue/Introduction

After patching a 2 node stretch cluster, when the hosts are directly connected you see the following errors in the vSAN Skyline health check

An Active/Active network configuration for vSAN is in use. 

Environment

vSAN (all versions)

Cause

With direct connect 2-node stretch clusters, if NIC teaming and failover settings have multiple uplinks set to active, it's possible for each host to power back up using different vmnics. This will result in the directly connected hosts not being able to communicate and will result in a partition, since vSAN only uses one active vmnic at a time. 

Resolution

Follow KB Direct connect vSAN 2-node stretch Cluster showing basic unicast connectivity error in skyline health and is network partitioned to resolve this.