Externally Stored Containers
There is no need to manage externally stored container data during data migration. Container data is data and, just like any other data, they stay on the production server during the migration process.
When you migrate a file with Otto, you are moving a clone from one server to another, such as from a development server to a production server. The clone contains no data at all. The migration process on the production server takes care of importing all of the data including links to the externally stored container data from the production files into the clones.