In last few years we had seen Server Load Balancer market getting over crowded. Almost every OEM is trying to launch either their own product or is offering white labelled or co-branded products from other OEM’s. Server load balancer could be pricey component in your Bill of Material. We had noticed that SLB’s comprises almost one third of your total network cost. In such scenarios, where you are willing to trust open source products, these open source server load balancers can help you bring the cost down without compromising on functionality and performance.
HAProxy is actually a general TCP load balancer with added features for HTTP. Because it can balance at the TCP level, other services can also be served by HAProxy, such as multiple MySQL or caching servers. HAProxy offers the most options of a true load balancer and scales extremely well. HAProxy lacks SSL offloading feature, so you must relay an additional service such as stunnel to receive requests and pass them to HAProxy. It Suppors tens of thousands of connections is clearly realistic with today’s hardware. Its mode of operation makes its integration into existing architectures very easy and riskless, while still offering the possibility not to expose fragile web servers to the Net
Pound is a lightweight HTTP-only load balancer. It offers many of the load balancing features of HAProxy without any of the web server capabilities. This keeps Pound small and efficient with easy-to-read configuration options. It does support SSL Offloading but caching is not available with this product.
Although primarily used as a reverse proxy cache, Varnish also includes functionality to act as a load balancer. It does not offer a great deal of configuration, but, if already using Varnish for caching, it may be possible to also make use of its load balancing abilities to greatly simplify an architecture. Similar to HAProxy, however, Varnish does not support SSL termination.
Pen is a load balancer for “simple” TCP-based protocols such as HTTP or SMTP. It allows several servers to appear as one to the outside. It automatically detects servers that are down and distributes clients among the available servers. This gives high availability and scalable performance.
Balance is a simple but powerful generic TCP proxy with round-robin load balancing and failover mechanisms. Its simple command line allows offers complete control in the realtime. Balance supports IPv6 on the listening side, which makes it a very useful tool for IPv6 migration of IPv4 only services and servers.