DRS rules fail to enable in vSphere Client and switch immediately back to not enabled

Products

• VMware vCenter Server

Issue/Introduction

You are trying to enable an existing or newly created DRS rule (for example a Host to VM affinity rule), while there are multiple other existing rules in the same cluster.

After changing the rule status to enabled, and leaving the wizard, it immediately goes back to being disabled.

 

Environment

vCenter Server 8.0 Update 2

Cause

This issue is caused by one or more of the existing rules having invalid (aka null) entries. These can be caused by either virtual machines or hosts referenced in them, which have been removed from the vCenter inventory.

The references for these objects can get stuck in the affinity rule, making it invalid.

Resolution

To fix the issue:

• review the other existing DRS rules in the cluster for invalid (null) entries such as missing VMs.
• remove these entries or the related DRS rule.
• try to enable the initially affected DRS rule again.