In this talk, we’ll delve into troubleshooting complex systems comprising hundreds or even thousands of services. We’ll address key questions like: What information do we require about each service? How do we structure dashboards for rapid comprehension of the system's current state? We'll also explore the effective utilization of observability signals - metrics, logs, traces, and profiles - discussing their respective applications and the insights they provide. Additionally, we'll examine automation strategies for root cause analysis, considering both complete and partial automation approaches.