Hypervisor
2.2 Hypervisor
Oracle VM Server is architected such that the hypervisor (or monitor, or Virtual Machine Manager) is the only fully privileged entity in the system, but is also extremely small and tightly written. It controls only the most basic resources of the system, including CPU and memory usage, privilege checks, and hardware interrupts.
2.3 Domains, Guests and Virtual Machines
The terms domain, guest and virtual machine are often used interchangeably, but they have subtle differences. A domain is a configurable set of resources, including memory, virtual CPUs, network devices and disk devices, in which virtual machines run. A domain is granted virtual resources and can be started, stopped and rebooted independently. A guest is a virtualized operating system running within a domain. A guest operating system may be paravirtualized or hardware virtualized. Multiple guests can run on the same Oracle VM Server. A virtual machine is a guest operating system and its associated application software.
Oracle VM Server guest operating systems may run in one of two modes, paravirtualized or hardware virtualized. In paravirtualized mode, the operating system guest kernel is recompiled to be made aware of the virtual environment. This allows the paravirtualized guest to run at near native speed, since most memory, disk and network accesses are optimized for maximum performance.
Figure 2–2 Virtual Machine Architecture
If support for hardware virtualization is available (either Intel VT or AMD SVM), the guest operating system may run completely unmodified. This hardware virtualized