All schema objects, application objects, configuration objects, and project settings are stored in the MicroStrategy metadata. Metadata is stored in a relational database with a predefined structure. The RDBMS for the metadata and warehouse do not need to be the same.
You can find the list of supported RDBMS platforms in the Readme that is installed with MicroStrategy products. To view the Readme, from the Start menu select Programs, then MicroStrategy Documentation, and then select Readme.