It is recommended that virtualization hosts have at least 2 GB of RAM. The amount of RAM required varies depending on:
- guest operating system requirements,
- guest application requirements, and
- memory activity and usage of guests.
The fact that KVM is able to over-commit physical RAM for virtualized guests must also be taken into account. This allows provisioning of guests with RAM requirements greater than physically present on the basis where not all guests will be at peak load concurrently. KVM does this by only allocating RAM for guests as required and shifting underutilized guests into swap.
A maximum of 1 TB of RAM per virtualization host is currently supported.