Symptoms

• You've VM running, however, when you pull the monitoring metric from:
  VHI admin panel >> Compute >> Virtual machines >> The VM you selected >>Monitoring tab, you'll see a constant usage of RAM presented as maximum usage. Eg: You set your ram to 4GB, it'll show constant 4GB reading.
   

Cause

• This could potentially happen if your guest OS isn't installed with the related ballooning drivers. Therefore, there's no way for the hypervisor to free the memory consumed on the host by this VM. Without the ballooning driver, it's expected behavior, where the metric shows as such.

Resolution

• To install the balloon driver according to your operating system. 
  
  To do so, mount and install the guest tools as described in (if you haven't do so):
  https://docs.virtuozzo.com/virtuozzo_hybrid_infrastructure_6_3_admins_guide/index.html#installing-guest-tools.html

Install the VirtIO balloon driver by:

1. Mount the windows guest tools ISO

2. Look under img/balloon/2K8R2 (example for os 2018R2)/ amd64

3. Right Click on the "balloon.inf", and click Install.

• Shutdown & Start again VM (Not reboot)

Your guest is now enabled with balloon driver, and it should expected to provide the metric according to the usage.