One of our clients recently came to us with a problem he's facing while working with our application. The error in the log file is the next:
System.Data.SqlClient.SqlException (0x80131904): Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. This failure occured while attempting to connect to the Principle server.
System.ComponentModel.Win32Exception (0x80004005): The wait operation timed out
As far as I know, that client has set up mirroring between two database servers and he's currently working on the fail-over server (They do that on purpose each now and then).
I am aware that I could use the
CommandTimeout property in my code to increase the time before a timeout is reached.
The application is working normally, so it's connecting to the database way before this error happens. Also, connecting through SSMS is working.
Note that, due to security reasons on my client-side, I can't use a profiler to narrow down the problem to a specific query or procedure.
What I am actually concerned about is the error message in bold.
Does that error mean that the actual problem is a connection problem between the Main DB Server and the Fail-Over server or could it also be triggered by a query taking more than the default 30 seconds?