Linux-VServer is a lightweight virtualization system used to create many independent containers under a common Linux kernel. To applications and the user of a Linux-VServer based system, such a container appears just like a separate host.
The Linux-Vserver approach to kernel subsystem containerization is based on the concept of context isolation. The kernel is modified to isolate a container into a separate, logical execution context such that it cannot see or impact processes, files, network traffic, global IPC/SHM, etc., belonging to another container.
Linux-VServer has been around for several years and its fundamental design goal is to be an extremely low overhead yet highly flexible production quality solution. It is actively used in situations requiring strong isolation where overall system efficiency is important, such as web hosting centers, server consolidation, high performance clusters, and embedded systems.