OS Virtualization
Sometimes called OS-level or shared OS virtualization, OS virtualization virtualizes servers on the operating system (kernel) layer. This creates isolated containers on a single physical server and OS instance to utilize hardware, software, data center and management efforts with maximum efficiency.
The two diagrams below show the hypervisor or hardware virtualization technology in comparison to OS virtualization.
Hypervisor Virtualization has a base layer (usually a thin Linux kernel shown here as a hypervisor or standard OS) that is loaded directly on the bare server. To allocate hardware and resources to the virtual machines (VMs), all hardware on the server must be virtualized. The next layer up shows each chip, board, etc. that must be virtualized so that it can be assigned to the VMs. Once in the VM itself, there is a complete copy of an operating system and finally the application or workload.
OS Virtualization is streamlined for the best performance, management and efficiency. At the base resides a standard host operating system, in the case of Parallels Virtuozzo that includes Windows and Linux. Next is the virtualization layer with a proprietary file system and a kernel service abstraction layer that ensure isolation and security of resources between different containers. The virtualization layer makes each container appear as a standalone server. Finally, the container itself houses the application or workload.
Read about the full advantages of Parallels Virtuozzo Containers.