What is a 'Guest'?
To talk about stuff, we need some naming. The physical machine is called 'Host' and the 'main' context running the Host Distro is called 'Host Context'. The virtual machine/distro is called 'Guest' and basically is a Distribution (Userspace) running inside a 'Guest Context'.
What kind of Operating System (OS) can I run as guest?
With VServer you can only run Linux guests. The trick is that a guest does not run a kernel on its own (as XEN and UML do), it merely uses a virtualized host kernel-interface. VServer offers so called security contexts which make it possible to seperate one guest from each other, i.e. they cannot get data from each other. Imagine it as a chroot environment with much more security and features.
- memory: Dynamically.
- CPU usage: Dynamically (token bucket)
You can put limits per guest on different subsystems.
- using ulimits and rlimits (rlimit is a new feature of kernel 2.6/vs2.0.) per guest, to limit the memory consumption, the number of processes or file-handles, ... : see Resource Limits
- CPU usage : see CPU Scheduler
- disk space usage : see Disk Limits and Quota
Note that you can only offer guaranteed resource availability with some ticks at the time.