VM memory usage heuristic over-reporting on ESXi 6.5

Products

• VMware vSphere ESXi

Issue/Introduction

• Virtual Machines are triggering the Virtual machine memory usage alarm.
• The VM Memory Usage/Active performance metric is higher compared to running on ESXi 6.0 or earlier.
  
  This issue is more prevalent in:
   
  • Virtual Machines with less configured memory
  • Virtual Machines that are highly utilized for at least short periods during the day.

Environment

VMware vSphere ESXi 6.5

Cause

A change in the large page promotion path in ESXi 6.5 causes the activity sampling to over-report and stay high despite decreasing workload activity.

Resolution

This issue is resolved in ESXi 6.5 U1.
 

This is a display problem only and has no performance impact on the Virtual Machine or the host it is running on.

 

To work around this issue, disable the Virtual machine memory usage alarm to avoid false positives:

1. Select the vCenter Server object in the navigation pane of the vSphere Web Client.
2. Click the Monitor > Issues.
3. Click Alarm Definitions and search for Virtual machine memory usage.
4. Select the alarm and click Edit, then un-check Enable this alarm.
5. Click Finish.

Additional Information

• vRealize Operations Manager capacity planning might be impacted unless the memory consumed model is used.
• If the reported memory activity is not only higher but constantly at 100%, see Memory usage alarm triggers for certain types of Virtual Machines in ESXi 6.x (2149787)