Concept / Term · Established
Reliability allowance
The amount of unreliability a service can tolerate while still meeting its SLO; teams use it to balance release speed against stability.
Field note
An error budget is the amount of unreliability a service can consume while still meeting its SLO. For a 99.9% availability objective, the remaining 0.1% is the budget for failures and maintenance.
Site Reliability Engineering introduced the concept as a practical way to turn the tension between shipping quickly and operating reliably into a shared calculation.
When the budget is healthy, teams can accept more release risk. When it is exhausted, reliability work and safer change take priority.
It replaces arguments between development and operations with an agreed measure of how much risk the service can currently tolerate.
In a sentence“We have spent this month’s error budget, so the next release waits until the incident fixes are complete.”