When you want to install additional components on a mission critical SQL server instance in production, you have to be very careful to find out which component requires SQL instance to be restarted and which does not. Otherwise, you will find your phone keep ringing. Here are two examples:
1) Database Replication doesn’t require SQL instance to be restarted. But it does need to restart the SQL Server Agent in order for it to work.
2) FULL Text Search does restart the SQL instance during the installation!!!