Memory Ballooning


New Member
Jul 2, 2023
Hi !

I'm facing an issue with my Windows Server virtual machines in Proxmox. All of these VMs constantly consume around 85% of RAM, as shown in the htop :
However, when I check the RAM usage through the Proxmox client, it indicates only 10% usage, which is quite confusing.

We have attempted to patch this problem by installing Ballooning, but unfortunately, it hasn't resolved the issue.

Is it possible to release this ram from the dedication in a way I haven't found?
check the RAM usage through the Proxmox client
What do you excatly mean by that?

When using the QEMU guest agent the PVE webUI will show as the VMs RAMs usage what Windows is telling the guest agent what the guest agent should tell the PVE host. Windows reports "available" RAM as "free" RAM. So what is shown as "free" isn't free in reality, but in use but at the same time "available" from the guest OSs point of view as it probably just is cache that could be dropped quickly when needed.
So check your windows task manager. You will probably see that Win is actually using the 85% of the RAM, just with 70% used for caching.

Also keep in mind that ballooning won't care if a guest OS needs that RAM or not. It will just steal the RAM and the guest OS has to handle that (even killing processes when running out of RAM).
And ballooning will only kick in once the host got less than 20% of free RAM left.


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