The AD FS configuration database stores all the configuration data that represents a single instance of AD FS 2.0 (also known as the Federation Service). You can store this configuration data in either a Microsoft SQL Server® database or using the Windows Internal Database. The Windows Internal Database is a Windows Server feature that is automatically installed on the computer whenever you complete the AD FS 2.0 Federation Server Configuration Wizard for the first time.
Since the wizard does not provide a UI option to choose SQL Server as the store for the AD FS configuration database it is understandable how many would continue to use the wizard defaults to see if it will work well for their infrastructure. It is highly possible that in time you may want to scale out your federation server farm to use more than 5 federation servers by migrating the configuration database to SQL Server. By migrating to SQL you will obtain scale, high availability and also be able to use SQL’s backup mechanisms.
Sound interesting? I thought so especially since I had the pleasure of working the Wiki booth yesterday with the author of the full article, Nick Pierson.
See the full article which was uniquely published on the Wiki first at http://social.technet.microsoft.com/wiki/contents/articles/ad-fs-2-0-migrate-your-ad-fs-configuration-database-to-sql-server.aspx.