GæsteOSer

GæsteOSer, or guest operating systems, are operating systems that run inside virtual machines hosted on a physical computer. They operate within a virtualized environment created by a hypervisor, which abstracts and emulates hardware resources for the guest.

Within a guest, the operating system runs as if on its own computer, using virtual devices such as a virtual CPU, memory, disk, and network interface provided by the hypervisor. The guest is isolated from the host and from other guests, providing security and stability boundaries. Common guest OS choices include Linux distributions, Windows, and, where licensing permits, macOS on Apple hardware.

Hypervisors come in two main types: Type 1 (bare-metal), which runs directly on hardware, and Type 2 (hosted), which runs on a host operating system. Performance overhead is mitigated by hardware-assisted virtualization (Intel VT-x/AMD-V) and, in some configurations, paravirtualization. Guest OSes support features such as snapshots, cloning, and live migration, enabling testing, development, and server consolidation. Licensing, device drivers, and compatibility with virtual hardware are important considerations when choosing a guest OS.