Diagnostic counters in SqlClient
Applies to: 
.NET Framework
.NET
.NET Standard
You can use Microsoft.Data.SqlClient diagnostic counters in multiple target frameworks to monitor the status of your application and the connection resources that it uses. Use performance counters in .NET Framework, and event counters in .NET Core and .NET Standard.
Note
When using Windows Authentication (integrated security), you must monitor either the pair number-of-active-connection-pool-groups and number-of-active-connection-pools event counters or the NumberOfActiveConnectionPoolGroups and NumberOfActiveConnectionPools performance counters. The reason is that connection pool groups map to unique connection strings. When integrated security is used, connection pools map to connection strings and additionally create separate pools for individual Windows identities. For example, if Fred and Julie, each within the same AppDomain, both use the connection string "Data Source=MySqlServer;Integrated Security=true", a connection pool group is created for the connection string, and two additional pools are created, one for Fred and one for Julie. If John and Martha use a connection string with an identical SQL Server login, "Data Source=MySqlServer;User Id=<myUserID>;Password=<myPassword>", then only a single pool is created for the <myUserID> identity.
In this section
Performance counters in SqlClient
Use Microsoft SqlClient Data Provider for SQL Server performance counters to monitor your application status and its connection resources by using Windows Performance Monitor or programmatically in .NET Framework.
Event counters in SqlClient
Use Microsoft SqlClient Data Provider for SQL Server event counters to monitor your application status and its connection resources in .NET Core and .NET Standard.