Linux Virtual Server
Linux Virtual Server (LVS) is a set of integrated software components for balancing the IP load across a set of real servers. LVS is a free and open-source project started by Wensong Zhang in May 1998. The mission of the project is to build a high-performance and highly available server for Linux using clustering technology, which provides good scalability, reliability and serviceability.
Components
LVS runs on a pair of equally configured computers: one that is an active LVS router and one that is a backup LVS router. The active LVS router serves two roles:
- To balance the load across the real servers.
- To check the integrity of the services on each real server.
Overview
Virtual server is a highly scalable and highly available server built on a cluster of real servers. The architecture of server cluster is fully transparent to end users, and the users interact with the cluster system as if it were only a single high-performance virtual server.
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 and make parallel services of the cluster to appear as a virtual service on a single IP address, and request dispatching can use IP load balancing technolgies 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.
