Ballooning not working?

[vescovialex]

Hello,

I have a question about ballooning of the memory.
PVE version 7.4.3

Totally I have 64GB of RAM.
Arc max for zfs is 4GB, if I shutdown all the VM's I have 7GB used, and that's ok.

Now I have 3 VM (Windows Server 2022) up&running with ballooning enabled,
On each VM I've installed virtio driver 0.1.229.

This are the VM's:
1st - 2GB MIN - 8GB
2nd - 2GB MIN - 8GB
3rd - 1GB MIN - 2GB (windows core edition)

Used memory for each VM:
1st - 975MB
2nd - 1,34GB
3rd - 657MB

Total for all VM's:
+/- 3GB

If we do some math 7GB of zfs and system + 3GB for VM's, total of 10GB used.

Now is used 26GB, like the total RAM I configured for the VM.

8+8+2+7=26GB

Where is the problem?

 

[leesteken]

Ballooning does not take away memory from VMs until there is 20% or less memory available on the Proxmox host. I don't think there is a problem, or did I misunderstand your situation/question?

 

[vescovialex]

Ok, I've thinking that ballooning and the MIN value working like the thin provisioning in the storage.

You configure 8GB of RAM and the system is now using 2GB, then on the host only 2GB is occupied from the VM.

 

[leesteken]

Ok, I've thinking that ballooning and the MIN value working like the thin provisioning in the storage.

Instead of the VM giving back memory that it does not use, the Proxmox host just takes memory when it needs it. This may crash programs inside the VM due to lack of memory, if you set the VM minimum memory too low.