My OpenNebula is using Debian hosts with KVM virtualization. I have read that KSM can significantly reduce the memory footprint when multiple similar VMs are running simultaneously. I currently have 10 different VM templates, each cloned 48 times (for my students).
Does anyone have any advice on this? Is it easy to implement it ? Is it risky?
The reason to use OpenNebula is that it helps you manage VM templates in an easy way (please check our doc: Managing VM instances). Also the KVM management should be suffice for your use case (KVM Node Installation).
Since we use KVM, and KSM is like a feature and can be activated pretty straight forward, you should be able to enable KSM over OpenNebula KVM.
There’s info on how to install KSM, on Red Hat documentation, that should work for this situation.