vSAN network connectivity lost while migrating VMkernel interfaces from vSS to vDS

Products

• VMware vSphere ESXi

Issue/Introduction

It was observed in /var/run/log/vmkernel.log that the vSAN cluster experienced a network partition after moving the vSAN VMkernel interface from a vSphere Standard Switch (vSS) to a vSphere Distributed Switch (vDS).

<DATE_TIME> In(###) vmkernel: cpu##:####### opID=########)Net: ####: connected vmk#  to <PORT_GROUP_NAME>, portID 0x######## <DATE_TIME> In(###) vmkernel: cpu##:#######)CMMDS: CMMDSAgentlikeCheckNodePath:####: <UUID>: Lost contact with leader path <vSAN_IP_ADDRESS> <DATE_TIME> In(###) vmkernel: cpu##:#######)DOM: DOMOwner_SetLivenessState:#####: Object <UUID> lost liveness [0x############]

 

Environment

VMware vSphere ESXi

Cause

There is an MTU mismatch: the vSAN VMkernel interface MTU is set to 9000, whereas the vDS MTU is configured as 1500.

Resolution

Please ensure that all network configurations on the vDS are identical to those on the vSS prior to the migration.