No, Haidong, I don't agree with you on "When you start SQL Agent, SQL Server Service will be started automatically, as SQL Agent service is dependent on SQL Server service."

For my understanding, it’s true that when you restart SQL Server, the SQL Agent will restarted automatically, but you are able to restart Agent without restart SQL Server, so my question is, If we put a job to run the your script automatically when the Agent is start, then do we need to check if the existing trace still active, and remove it first before we create another one ? I am afraid we may create multi trace in the system.

Again, thank you for your time.