In the last decade, server load balancers (SLBs) were hailed as the solution to website scalability and availability problems. These devices balanced traffic across servers to ensure the site was available and could handle traffic spikes. If one server went down, the load balancer redirected traffic. When a site got “slashdotted” you could add more servers transparently.
Flash forward to 2010; Web servers aren’t just delivering static content, they’re delivering apps. Businesses are using web based applications to deliver mission critical functionality to employees and customers. Simple load balancing is no longer sufficient.