I found this article regarding Linq-to-SQL and SQL Server connection pooling: MSDN Blog
From what I assume from the article, is that Linq-to-SQL using the same Max Pool Size setting just as if it was an ADO object.
I have an C# app that is hitting the database pretty hard. Is there a way to tell if I am hitting my connection limit? How can I tell if my connections are being queued?
Use performance counters. You should be interested in following counters:
NumberOfPooledConnections– how many connections your pool mantainNumberOfActiveConnections– how many connections are in useNumberOfFreeConnections– how many connections are not in useLast two counters require some modification in your application configuration.
Another article about working with these counters.