To implement a reliable and scalable infrastructure, we must provide redundancy. This means redundancy in:
- Hardware: We must deploy our application across multiple physical hosts, each (ideally) at different geographical locations. This is so that if one data center is offline or destroyed, services deployed at the other data centers can keep our application running.
- Software: We must also deploy multiple instances of our services; this is so that the load of handling requests can be distributed across them. Consequently, this yields the following benefits:
- We can route users to the server which provides them with the quickest response time (usually the one closest geographically to the user)
- We can put one service offline, update ...
