What is saturation?

Saturation in the context of SRE and platform engineering is the state of a system when its resources are fully utilized and cannot handle additional load. For example, if a server's request processing threads are exhausted or the task queue is full, the system is considered saturated. This leads to delays, errors, and reduced performance. Saturation is one of the three key indicators of system health (along with latency and errors). Managing saturation helps prevent service degradation and failures.