12.0 Load Balancing with Linux Virtual Server

The goal of Linux Virtual Server (LVS) is to provide a basic framework that directs network connections to multiple servers that share their workload. Linux Virtual Server is a cluster of servers (one or more load balancers and several real servers for running services) which appears to be one large, fast server to an outside client. This apparent single server is called a virtual server. The Linux Virtual Server can be used to build highly scalable and highly available network services, such as Web, cache, mail, FTP, media and VoIP services.

The real servers and the load balancers may be interconnected by either high-speed LAN or by geographically dispersed WAN. The load balancers can dispatch requests to the different servers. They make parallel services of the cluster appear as a virtual service on a single IP address (the virtual IP address or VIP). Request dispatching can use IP load balancing technologies or application-level load balancing technologies. Scalability of the system is achieved by transparently adding or removing nodes in the cluster. High availability is provided by detecting node or daemon failures and reconfiguring the system appropriately.