Virtual server is a scalable and highly available server built on a cluster of real servers.
The architecture of the cluster is transparent to end users, and the users see only a single virtual server. The front-end of the real servers is a load balancer, which schedules requests to the different servers and make parallel services of the cluster to appear as a virtual service on a single IP address. Scalability is achieved by transparently adding or removing a node in the cluster. High availability is provided by detecting node or daemon failures and reconfiguring the system appropriately. The basic goal of the Linux Virtual Server Project is to produce a high-performance and highly available server for Linux based on clustering, which provides a good scalability, reliability and serviceability.