Building out a highly available website means that it is fault-tolerant and reliable. A best practice is to put your web servers behind a load balancer not only to distribute load, but also to mitigate the risk of an end user accessing a failing web server. However, traditional load balancing funnels traffic into a single-tenant environment—a single point of failure. A better practice is to have a distributed load balancer that takes advantage of the features of the cloud and increases the fault-tolerance abilities on the load balancer. GoGrid’s Dynamic Load Balancer service is designed around a software-defined networking (SDN) architecture that turns the data center into one big load balancer.

GoGrid’s Dynamic Load Balancer offers many features, but one of its core features is high availability (HA). It is HA in two ways.

First, on the real server side, deploying multiple clones of your real servers is a standard load-balancing practice. That way, if one of your servers goes down, the load balancer will use the remaining servers in the pool to continue to serve up content. In addition, each GoGrid cloud server that you deploy as a web server (in the real server pool) is most likely on a different physical node. This setup provides additional protection in the case of hardware failure.

Second, on the Dynamic Load Balancer side, the load balancers are designed to be self-healing. In case of a hardware failure, Dynamic Load Balancing is designed to immediately recover to a functioning node. The Virtual IP address of the Dynamic Load Balancer (the VIP) is maintained as well as all the configurations, with all the changes happening on the back end. This approach ensures the Dynamic Load Balancer will continue to function with minimal interruption, preventing the Dynamic Load Balancer from being a single point of failure. Because the load balancer is the public-facing side of a web server, whenever it goes down the website goes down. Having a self-healing load balancer therefore makes the web application more resilient.

Users with websites or applications that need to always be available would benefit from including GoGrid’s Dynamic Load Balancing in their infrastructure. The load balancer is important for ensuring the public side of a service is always available; however, including easily scalable cloud servers, the ability to store images of those servers in persistent storage, and the option to replicate infrastructure between data centers with CloudLink are all important elements of a successful HA setup.

(more…) «High Availability with Dynamic Load Balancers»