vCenter Server 'Memory Usage' alarm not triggering despite high memory consumption on the host

Products

• VMware vCenter Server

Issue/Introduction

The memory usage alarm in vCenter Server was not being triggered, even though it was properly configured and enabled. 
vCenter logs showed no relevant exceptions or backend service issues. Other alarms were functioning normally, isolating the problem to this specific alarm configuration.

Environment

vCenter 7.0
vCenter 8.0

Cause

A configuration inconsistency or corruption was identified in the alarm definition, likely introduced after the alarm was manually reset to a green state sometime back. 

 

Resolution

The memory usage alarm was reconfigured using default parameters.
Once recreated with the default settings, the alarm began triggering correctly. 

Additional Information

Alarm definition was verified to be enabled.
Attempts to disable and re-enable the alarm did not resolve the issue.