The server administrators need to perform backup to an external USB device. What rules and exceptions are needed so that the data will not be blocked?
The most secure way is to create a Group Directories connection if there isn't an existing one. Then create a User Group for the server(s) in question and the service account that the backup is run as. In the policy, add the newly created User Group to the exception.
Also, it is possible to base exceptions to External Devices via their DeviceIDs. Use the DeviceID.exe, part of the Endpoint tools, to get the information of that USB device and then add that device ID information to the exception. For more details on setting that up, please see the Admin Guide (only available in version 11 and higher).