Applications running on the VM guest OS experience failover during snapshot deletion

Products

• VMware vSphere ESXi

Issue/Introduction

• The applications in a primary-secondary configuration are running on 2 VMs.
• Failover occurred between the primary and secondary nodes during the snapshot removal of the VM hosting the primary nodes.
• The VM has one snapshot and has been running on it for over 72 hours.
• The vmware.log shows the VM was stunned for a few seconds while deleting the snapshot:
  
  [YYYY-MM-DDTHH:MM:SS] In(05) vcpu-# - CPT: vm was stunned for ####### us  

Environment

VMware vSphere ESXi 7.x

Cause

The stun occurs to allow the changes to be written back to the base disk from the delta disks. The size of the VM snapshot will increase over time, leading to a longer VM stun duration which causes a failover in the sensitive application.

Resolution

Do not use a single snapshot for more than 72 hours. Refer to: Best practices for using VMware snapshots in the vSphere environment