Maintenance Mode allows you to temporarily stop alert generation and the collection of performance metrics for the selected SQL Server instances. Using Maintenance Mode on one instance does not prevent the collection of performance metrics and notifications for those instances that are not in Maintenance Mode.
If you open a SQL Diagnostic Manager dashboard for an instance that is in Maintenance Mode, real-time data collection will be attempted.
It is possible to enable or disable maintenance mode on several SQL Server instances, see About Mass Maintenance Mode.
Uses for putting a SQL Server instance into Maintenance Mode
Enable Maintenance Mode before you begin any regularly scheduled maintenance or testing on a monitored SQL Server instance. You can also enable Maintenance Mode when you need to bring a SQL Server instance offline for unplanned diagnostics.
Be aware that the total number of monitored SQL Server instances allowed by your license includes monitored instances that are in Maintenance Mode.
Bring the SQL Server back online in SQL Diagnostic Manager
Disabling Maintenance Mode allows SQL Diagnostic Manager to resume performance statistics collection and alert generation for the selected SQL Server instance. Before you enable Maintenance Mode, make sure you complete all maintenance and testing on the target SQL Server instance.
If you have a SQL Server instance in Maintenance Mode and are ready to bring it back online in SQL Diagnostic Manager, click Maintenance Mode on the Server Overview tab.