The Select Counter Type window of the Add Custom Counter wizard allows you to choose the method you want SQL Diagnostic Manager to use when collecting the counter. SQL Diagnostic Manager offers the following counter types:
Windows System Counter
Select this option to pick from counters that include both those available in Windows System Performance Monitor (PerfMon) and Windows Management Instrumentation (WMI) performance counter types.
SQL Server System Counter
Select this option to pick from counters that are gathered via standard T-SQL from SQL Server.
Custom SQL Script
Select this option to enter a custom T-SQL script to monitor variables such as those which are not connected to the operating system or SQL Server counters or metrics that are very specific to your environment such as a row count on a particular production table. Note that your script must return a single numeric value.
Virtual Machine Counter
Select this option to pick from counters collected using an API from VMware or Hyper-V.
Access the Add Custom Counter wizard
You can open the Add Custom Counter wizard by clicking Administration > Custom Counters, and then clicking Add in the Custom Counters view.