(mon+heartbeat+fake+coda solution) Virtual server is a highly scalable and highly available server built on a cluster of real servers. The architecture of cluster is transparent to end users, and the users interact with the system as if it were only a single high-performance virtual server.

The Linux Virtual Server as an advanced load balancing solution can be used to build highly scalable and highly available network services, such as scalable web, cache, mail, ftp, media and VoIP services. link