Virtual machine become inaccessible during the rolling reboot of ESXi servers

Products

• VMware vSAN

Issue/Introduction

• Multiple VMs may become inaccessible during the rolling reboot of the ESXi host part of vSAN Cluster.
  
  
• Virtual machines configured with vSAN RAID protection may also become inaccessible.

Environment

VMware vSAN 7.x
VMware vSAN 8.x

Cause

This issue may occur if multiple hosts are taken into maintenance mode at the same time by selecting the option 'No data migration' option.

With 'No data migration' option, vSAN does not evacuate any data from this host. So, the objects which are non-complaint may become inaccessible if its having any components placed on the the host taken into maintenance mode.

/var/run/log/vsansystem.log will report the maintenance mode option selected for the host.

2025-09-07T18:44:50.444Z info vsansystem[2104987] [vSAN@6876 sub=VsanSystemProvider opId=mf6drma7-284508-auto-63j1-h5:70024372-58-8a-9a00-61d7] Number of nodes in cluster: 9. Decommission mode: No Action


Below are the Decommission modes reported in the vsansystem.log::
no Action --> No data migration
Ensure Accessibility --> Ensure Accessibility
Evacuate vSAN Data --> Full data evacuation

Resolution

Select 'Ensure Accessibility' option for maintenance mode to perform tasks like rolling reboot, where the host is expected to be back online in a short time.

Note: 
Objects will be in reduced availability when 'Ensure Accessibility' option is selected for maintenance mode. If a failure occurs on another host during this time, you might experience data loss in the cluster.

Use data migration pre-check to identify the impact of migration options when placing a host into maintenance mode or removing it from the cluster, as mentioned in the below article.

Check the Data Migration Capabilities of a Host in the vSAN Cluster

 

Additional Information

Place a Member of vSAN Cluster in Maintenance Mode