Errors after Upgrading vSAN Witness to 9.1 in Mixed-Version Environments - VMware Cloud Foundation

Products

• VMware vSAN

Issue/Introduction

 Following an upgrade of the vSAN witness node to version 9.1 while the cluster data nodes remain at version 8.0u3, the following alarms are generated:

• Witness Node: "License assignment failed for this host."
• vSAN Cluster: "vSAN cluster alarm 'Disk format version'."

Confirm the environment is in a mixed-version state where the vSAN witness node is running version 9.1 and the cluster data nodes are running version 8.0u3. The alarms triggered in vCenter are indicative of version incompatibility and licensing mismatch.

Environment

VMware vSAN, VMware Cloud Foundation

Cause

Mixed-version environments (Witness node at 9.1, data nodes at 8.0u3) are unsupported in VMware Cloud Foundation. The vSAN witness node upgrade introduces licensing and disk format compatibility checks that conflict with the data nodes running on the older version.

Resolution

To restore version parity and system stability:

1. Redeploy Witness Node: Deploy a new vSAN witness node using version 8.0u3. This ensures compatibility with the existing cluster data nodes.
2. Do Not Acknowledge Alarm: Do not acknowledge the "Disk format version" alarm currently present in the cluster. Acknowledging this alarm prematurely can cause severe cluster issues/problems.
3. Future Upgrade: Schedule a maintenance window to upgrade both the witness node and the cluster data nodes to version 9.1 simultaneously. Only after both tiers are at the same version should the vSAN cluster be considered fully supported and compatible.