Telemetry data helps build a storyboard view that shows what that user and other users were doing when the issue was reported. In addition to user activity tracking, a rich set of SQL data is also available for performance troubleshooting using SQL NOW:
As shown in the preceding screenshot, Environment monitoring gives you information about the state spanning user load, activity load, SQL, server utilization, and so on spread across a configurable time scale.
Refer to Chapter 2, Implementation Methodology and Tools, for LCS - tooling called system diagnostics and its usage, which also plays a significant role in proactive monitoring.