For instance, a team building a photo-sharing website might want to avoid using a service that promises very strong durability and low cost in exchange for slightly lower availability, though the same service might be a perfect fit for an archival records management system.

To measure an SLO, it’s important to first define some Service Level Indicators (SLIs). Using intuition, experience, and an understanding of what users want helps us define SLIs, and with that comes SLOs and Service Level Agreements (SLAs). These measurements describe basic properties of metrics that matter, what values we want those metrics to have, and how we’ll react if we can’t provide the expected service. Ultimately, choosing appropriate metrics helps to drive the right action if something goes wrong, and also gives the team confidence that a service is healthy.