Removing Single Points of Failure
Your system has been running fine for months. Then one server fails. A single server. Suddenly your entire application is down, thousands of users are affected, and your on-call engineer is scrambling at 3 AM.
This scenario plays out more often than it should. The root cause is almost always the same: a Single Point of Failure (SPOF), a component whose failure brings down the entire system.
The tricky part about SPOFs is that they often hide in plain sight. Your architecture diagram might look perfectly reasonable, but somewhere in that flow is a component with no backup, no failover, and no redundancy. When it fails, and it will fail, everything stops.
In this chapter, we will walk through how to spot these weak points, understand why they matter, and apply battle-tested strategies to eliminate them across every layer of your architecture.