After upgrading your old TFS 2008 environment to a TFS 2010 environment,the old databases are merged into the new TFS_Configuration and TFS_DefaultCollection databases. So you are left with some unused databases that eat up your diskspace. So after you have confirmed that your new environment is doing it’s job, you can safely drop the following old databases:
- TFSActivityLogging
- TFSBuild
- TFSIntegration
- TFSWarehouse
- TFSWorkItemTracking
- TFSWorkItemTrackingAttachments
- TFSVersionControl