An optimization that can be applied to any computer cluster consists of balancing the requests among the nodes, so that all of them have approximately the same amount of work. The clients connect to a load balancer, which acts like a proxy trying to equally redirect the communication. Several load balancers exist, both open source and proprietary ones. Most of them are generic balancers, designed to work with any communication. So, they can be used for web servers, file servers, or in general, any type of servers. Not all load balancers perform well with database servers.

In this book, we will focus on a load balancer that has been specifically designed for Galera Cluster: Galera Load Balancer.