In some situations you might see that the Memory usage of a VM is higher after the upgrade. Maybe even a bit over 100%.
If the VM does not report detailed memory usage, Proxmox VE will show the host's view of the memory usage. With Proxmox VE 9, the accounting of the memory usage on the host has been adapted and takes the memory overhead of the VM into account. Therefore, the percentage may spike to over 100% in some cases.
If the new Host memory usage field is the same as the Memory Usage field in the VM's summary panel, then Proxmox VE was unable to gather the VM's internal memory usage information.
This happens if one of the following conditions applies:
- The Ballooning Device has been disabled in the advanced memory settings of the VM. This removes the communication channel to gather the guest's internal memory usage information.
- The guest does not report back any detailed memory usage information.
- The guest does not report back any detailed memory usage information.For example, FreeBSD is known to not report memory usage details, which includes popular firewalls like pfSense or OPNsense.
- If the BalloonService on a Windows guest is not installed or not running.
https://pve.proxmox.com/wiki/Upgrade_from_8_to_9#VM_Memory_Consumption_Shown_is_Higher