After installed the AX 2012, we would found that there are five database created in the SQL server.
1、MicroSoftDynamicsAxapta：The main database for AX, all the system data is stored in it, AOS connects to this database to process the all system transactions.
2、MicrosoftDynamicsAx_Model：All the AX 2012 AOT elements is stored in this database rather than the earlier version where it is stored in the files.
3、MicrosoftDynamicsAxBaseLine：All earlier version‘s apllication files would be stored in this database, AX will compare and analyze it before upgrading.
4、ReportServer：SSRS report service.
5、ReportServerTempDB：SSRS report template database.
原文：http://www.cnblogs.com/Jinnchu/p/5462186.html