The Linux Virtual Server Project is an open source project started by Wensong Zhang to cluster many real servers together into a highly available, high performance virtual server.

The LVS handles connections from clients and passes them on the the real servers (so called Layer 4 switching) and can virtualise almost any TCP or UDP service, like HTTP, HTTPS, NNTP, FTP, DNS, ssh, POP3, IMAP4, SMTP et cetera and is fully transparent to the client accessing the virtual service.

Commercial products to achieve the same exist, but the Linux Virtual Server Project unifies all their functionality with all the quality, flexibility and pricing advantages that open source development brings.

Combined with other tools from the Linux High Availability Project like heartbeat, multiple LVS and real servers can be combined in a fail over setup to eliminate all single points of failure.

Combined with intelligent DNS servers, even geographical load balancing can be tackled, providing disaster-safe service.

It is possible to build highly scalable, highly available clusters for a multitude of applications, most notably E-Commerce platforms.

The TurboCluster announcement by TurboLinux has raised a lot of public attention, one going as far as predicting the split of the Linux kernel development over these patches.

Their claim to being the world's first software Linux clustering solution rests squarely on their initial use of the Linux Virtual Server Project.

Compared to other products, the Linux Virtual Server provides many unique features:

• Supports multiple scheduling algorithms for dispatching connections to the real servers, and further schedulers can be added as modules,
• forwarding to the real servers can either be done using network address translation, fully transparent to the real servers, or using tunneling or direct routing, which provides very high performance,
• a robust and stable code base,
• a large, world-wide user and developer base, and thus the maturity provided by world-wide peer review,
• proven reliability in the field and real world applications.

A sampling of projects and companies which currently use the Linux Virtual Server Project include:

• One of the largest computer manufacturing companies in the world deploys two LVS clusters for American and European operations, which consist of four dual processor servers each.
• www.linux.com is using quite a few VA Research Linux servers as a LVS cluster for the mentioned web site,
• JANET Web Cache System, the UK national cache service, run a virtual proxy server with 11 real servers, which handles a throughput of 50Mbit/s during peak hours, and a daily turnover of about 20 Million HTTP requests/200Gb per day.
• NetWalk is using the LVS for 1024 virtual services in a redundant fail over setting with many real servers, which includes the US mirror of the LVS project ,
• Greenheck, five nodes,
• ID Media, two LVS and four Solaris web servers,
• Red Hat has included the LVS into their latest release of Red Hat Linux, is actively developing a graphical user interface to control the LVS, called piranha, and provides commercial international support,
• teuto.net is hosting the LVS site and mailing list, and also provides commercial support and projects within Germany.

The LVS Project provides a stable foundation for your projects, and we look forward to hearing from you.

We look especially forward to hearing from you if you are good at web design and feel like overhauling the LVS web site or want to provide documentation and admin tools.

In the future, we'll have better admin tools, better interoperation of the different tools, integration into the Netfilter framework and tighter integration with the Linux HA effort.

Please feel free to join the mailing list and contact us!

Resources:

• The Linux Virtual Server Project
• The LVS mailing list
• Talks given on the LVS project:
  • Joseph Mack, at Linux Expo'99
  • Lars Marowsky-Brée, at Linux Kongress'99
• The High Availability Linux Project

Signed,

	Joseph Mack
	Lars Marowsky-Brée
	Alan Robertson
	Wensong Zhang