Wondering what Service Level Objectives (SLOs) are?, this article will explain the service level objectives concepts and how they relate to SLAs, SLIs, and Error Budgets (EBs).
SLOs quantify customer’s expectations for reliability and start conversations between product and engineering on reliability goals and action plans when the goal is at risk. An example SLO for a service is: 99% availability in a rolling 28-day window
Change brings instability, which will inevitably lead to failure. Not only is 100% reliability an impossible target, but it would also mean that you can’t make any changes to the service in production. So expecting perfect reliability is the same as choosing to stop any new features from reaching customers and choosing to stop competing in the market.
Increasing the reliability target to no end is not a great business decision. The goal is not perfection, but making customers happy with just the right level of reliability. Once the customers are satisfied with the service, extra reliability offers little value.