RAM USAGE

[rackdie]

Hello there, i have a 64gb ram server and have 2 vm running on it one has 50gb allocated other has 6gb allocated. Both devices have ballooning enabled and latest stable virtuo driver installed. But in images i have attached, you can clearly see max 7gb being used but my datacenter dashboard shows 89-90% ram used. if i launch another vm it doesnt free up space and causes both 50 gb vm and the other i launch to crash after windows logo. any help will be appreciated, since i cant use more vm's at a time and it causes crashing of vm

 

[Dunuin]

In case you are using ZFS its ARC might use up to 50% of your RAM, so 32GB, in case you didn't limited it manually. And then make sure to differentiate between GB and GiB. Your VMs got 50/6 GiB of RAM and not GB. 56 GiB = 60,13 GB. And then a VM will need more RAM than you assign to that VM, as the KVM process will have overhead too. And in case you have chosen a caching mode like writeback this will also consume additional RAM of your host. And PVE itself wants 2GB of RAM. And RAM might fragment, which makes some of your RAM unusable. So you are probably overprovisioning your RAM.

And if you use PCI passthrough a VM will always consume the full RAM you assign. And in case of Windows VMs with guest agent enabled PVE will show wrong RAM utilization, where RAM used by the guest for caching will be shown as "free" while RAM used for caching still consumes the full physical RAM.