Technology selection for architectural reliability

Application reliability often looks at the availability of the application to serve users. Several factors go into making your application highly available. However, fault tolerance refers to the built-in redundancy of an application's components. Your application may be highly available but not be 100% fault-tolerant. For example, if your application needs four servers to handle the user request, you divided them between two data centers for high availability. If one site goes down, your system is still highly available at 50% capacity, but it may impact user performance expectations. However, if you create equal redundancy in both sites with four servers each, your application will not be only highly available but will be 100% fault-tolerant.

Suppose your application is not 100% fault-tolerant. In that case, you want to add automated scalability, defining how your application's infrastructure will respond to increased...