VMs Down after placing one of the vSAN nodes in maintenance mode.

Products

• VMware vSAN

Issue/Introduction

Symptoms:

• From vCenter UI VMs shows inaccessible.
• One vSAN Node is put into maintenance mode. The host might have placed in maintenance mode with no data migration.

Environment

VMware vSAN 7.x

VMware vSAN 8.x

Cause

The issue would occur when there are vSAN objects configured with FTT=0 storage policy and the host was put into maintenance mode with noAction (No Data Migration).

Reviewing the inaccessible object health may show policy information as below.

      Object UUID: 3bfd0962-####-####-####-f403xxxxae50
   Version: 20
   Health: inaccessible - Lost data availability. (APD)
   Owner: 00000000-0000-0000-0000-000000000000
   Size: 0.00 GB
   Used: 0.00 GB
   Used 4K Blocks: 0.00 GB
   Policy:
      stripeWidth: 1
      cacheReservation: 0
      proportionalCapacity: [0, 100]
      hostFailuresToTolerate: 0
      forceProvisioning: 0
      spbmProfileId: 8b04efa0-####-####-####-2610####458a

After putting the host into maintenance mode, this can be validated by clicking on the Problematic VM > click on monitor > click on physical disk placement. This would show the absent components as below.

Resolution

To resolve the immediate issue, exit the host from maintenance mode and it would bring back the components and make the VM accessible.

Also, when  there are vSAN objects with storage policy FTT=0, it is recommended to always use Ensure Accessibility option while putting the host into maintenance mode for the hardware/software maintenance activity.

Refer: Place a Member of vSAN Cluster in Maintenance Mode