ESXi hosts disconnected with vCenter Server during backup software stunned vCenter for a prolonged time

Products

• VMware vCenter Server

Issue/Introduction

• Multiple ESXis disconnected from vCenter and recovered automatically.
• The vCenter Server /var/log/vmware/vpxd/vpxd.log shows ESXi host heartbeat missed.
  info vpxd[07138] [Originator@6876 sub=HostCnx opID=CheckforMissingHeartbeats-xxxxxxxx] [VpxdHostCnx] No heartbeats received from host; cnx: <ESXi-uuid>, h: host-XX, time since last heartbeat: XXXXXms
• ESXi hosting vCenter /var/run/log/vmkernel.log shows VM stunned for a long time in the corresponding timestamp.
  In(05) vcpu-0 - CPT: vm was stunned for XXXXXXXX us

Environment

VMware vSphere ESXi 8.0.x

VMware vCenter Server 8.0.x

Cause

• Backup task creates snapshot and deletes vCenter snapshots.
• Creating and deleting lots of snapshots will increase the VM's Stun Time. It will suspend VM I/O, causing VM in stun status.

 

Resolution

Please refer to VM unresponsive aritcle.
Virtual Machine unresponsive during snapshot creation/deletion

Consider vCenter file-based backup rather than snapshot backup, refer to Configure and Schedule Backups