Chapter 3: Understanding Monitoring and Alerting to Target Reliability

Reliability is the most critical feature of a service or a system. Site Reliability Engineering (SRE) prescribes specific technical tools or practices that help measure characteristics to define and track reliability, such as SLAs, SLOs, SLIs, and Error Budgets. Chapter 2, SRE Technical Practices – Deep Dive, took a deep dive into these SRE technical practices across multiple topics, including a blueprint for a well-defined SLA, the need for SLOs to achieve SLAs, the guidelines for setting SLOs, the need for SLIs to achieve SLOs, the different types of SLIs based on user journey categorization, different sources to measure SLIs, the importance of error budgets, and how to set error budgets to make a service reliable.

SLAs are external promises made to the customer, while SLOs are internal promises that need to be met so that SLAs are not violated. This raises a raft of important questions:

• How...