In this post, Alexis Lê-Quôc discusses the importance of a structured approach to monitoring systems, emphasizing that effective monitoring extends beyond symptom detection to diagnosing root causes. Drawing from the experience of monitoring large-scale infrastructure and insights from experts like Brendan Gregg and Baron Schwartz, the article outlines a methodical process for diagnosing issues. It highlights the significance of three main types of monitoring data—work metrics, resource metrics, and events—to thoroughly understand system health and functionality. The post suggests starting investigations with work metrics of the highest-level systems to determine problems, then examining resource metrics if necessary, and considering any correlated events that might have caused the issue. It stresses the importance of pre-built dashboards for quick access to relevant data during outages and underscores a systematic framework for problem investigation, urging feedback from users on this approach.