LINUX VIRTUAL SERVER

Linux Virtual Server (LVS) is load balancing software for Linux kernel–based operating systems.

LVS is a free and open source project started by Wensong Zhang in May 1998, subject to the requirements of the GNU public license (GPL), version 2. 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.

The major work of the LVS project is now to develop advanced IP load balancing software (IPVS), application-level load balancing software (KTCPVS), and cluster management components.

• IPVS: an advanced IP load balancing software implemented inside the Linux kernel. The IP Virtual Server code is merged into versions 2.4.x and newer of the Linux kernel mainline.^[1]
• KTCPVS: implements application-level load balancing inside the Linux kernel, as of February 2011 still under development.^[2]

LVS can be used for building highly scalable and highly available network services, such as web, email, media and VoIPservices, and integrating scalable network services into large-scale reliable e-commerce or e-government applications. LVS-based solutions already have been deployed in many real applications throughout the world, including Wikipedia.

The LVS components depend upon the Linux Netfilter framework, and its source code is available in thenet/netfilter/ipvs subdirectory within the Linux kernel source. LVS is able to handle UDP, TCP layer-4 protocols as well as FTP passive connection by inspecting layer-7 packets. It provides a hierarchy of counters in the /proc directory.