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An IP-based load balancing solution

Exploring Piranha

Khurram Shiraz

Red Hat's Piranha load balancing software is based on the Linux Virtual Server concept. We show you how to configure and test your setup.

Load balancing is a major requirement for most web server farms. These web servers are expected to serve thousands of requests per second. Consequently, load balancing is no longer a luxury but an essential requirement for both performance and availability. Initially, hardware load balancers were used, but with the increasing costs of hardware and the growing maturity in software, the trend now is to use software load balancers.

Linux Virtual Server

Linux has a major advantage over other operating systems in this regard, because most of its commercial distributions (e.g., Red Hat and openSUSE) already provide inherent load balancing capabilities for most network services, such as web, cache, mail, FTP, media, and VoIP. These inherent capabilities are based on Layer 4 switching, allowing Linux servers to constitute special kinds of clusters known as LVS clusters.

LVS stands for Linux Virtual Server [1], which is a highly scalable and highly available server built on a cluster of real servers, with the load balancer running on the Linux operating system.

The Linux Virtual Server Project implements Layer 4 switching in the Linux kernel, which allows TCP and UDP sessions to to be load balanced between multiple real servers. This method provides a way to scale Internet services beyond a single host.

Note that the architecture of this virtual IP cluster is fully transparent to end users, and the users interact as if it were a single, high-performance, real server. Different variants of LVS technology have been adopted by many Linux distributions, including Debian, Red Hat, and openSUSE.