Error Budget
An error budget is the allowance of unreliability (1−SLO); once exhausted, feature work freezes in favor of stability, balancing speed and reliability.
Purpose
Quantify tolerable unreliability, balancing feature development with system stability.
Mechanism
E.g., SLO=99.9% monthly availability gives an error budget of 0.1%*43200s=43.2 minutes of downtime. Within budget, ship new features freely. Exhausted, freeze features and focus on stability. Shared visible metrics drive consensus.
Use cases
- Reliability balance
- Release cadence
- SRE