As per today, this functionality is only available as a private preview.
In the Control Panel of your VSO, click on “Export”
After a few minutes, you can download …. the instructions and your user IDs as part of a Zip file (see details next).
Note, I was disapointed to to find my *.bak file here, but rather, the instructions offers a secure way to get your backup.
Now your data are stored in an Azure Blob storage. And the Zip file downloaded contains:
The ReadMe file contains the instructions. Hurry, your backup will only be available 10 days (as it cost to store your data in a Blog Storage, and it is also not to secure to let the heart of your application in this location !).
|Readme.rtf (as per today 2014.04.05)|
Included in the export with this README is a settings file (.ini) and an identity mapping file (.csv). The settings file includes critical information for TFS on how to access your exported data, and will also define the name for your new on-premises collection database. The identity mapping file contains a list of all the Visual Studio Online (VSO) identities in your exported collection and should be filled out with the on-premises user accounts that these identities will map to.
To attach your exported collection to an on-premises instance of TFS:
1. Run the TFSConfig CloudImport command, which will use settings.ini to import your VSO data from Azure Blob Storage into the on-premises SQL Server you specify.
2. After the TFSConfig CloudImport command completes, create a backup of the restored database prior to attaching it to your TFS Server. The attach wizard makes changes that cannot be reverted, so having a backup is important.
3. Fill out the identity mapping file (.csv) to map VSO identities to local identities.
4. Execute the TFS Attach wizard to add your collection to your TFS instance.
For more detailed instructions on how to attach an exported collection, visit: http://go.microsoft.com/fwlink/?LinkId=329850
Given that Team Foundation Server is updated less frequently than Visual Studio Online, you may find that some of the features you were using in the cloud are not available in on-premises TFS. These features and their corresponding data were removed from your collection during the export process.
To read more about the specific features that are lost when moving from Visual Studio Online to the most recent release of Team Foundation Server, visit: http://go.microsoft.com/fwlink/?LinkId=329853
Here is the documentation and the pre-requisites : http://msdn.microsoft.com/en-us/library/7cb80f0d-0119-4277-82e8-719a8db1796e