The Mirroring History report lets you view the status of select mirroring metrics at the time of each SQL Diagnostic Manager scheduled refresh for the specified period.
You can filter the results by time, tag, server, and database, and also choose to view only problems as defined in your alerts. Fields showing metrics corresponding to alerts are color-coded according to the alert.
When to run this report
You should run the Mirroring History report when you want to analyze the historical health of your mirrored SQL Server databases by identifying and tracking critical values for key performance metrics. Each red or yellow value in the report grid corresponds to a raised alert. These visual warnings represent points in time when the metric reached or exceeded the specified alert threshold.
By default, SQL Diagnostic Manager alerts on many performance-related SQL Server metrics. You can also configure alerts and create custom counters to track specific performance data.