While working on the Drupal 8 module, I discovered this option to keep field storage persistent.
By default a field storage is removed when it’s no longer used. This happens when you simply delete fields. If all the fields that use the storage have been deleted, then the field storage is no longer needed and it’s removed.
So to keep it around simply set persist_with_no_fields to TRUE. By default it’s set to FALSE.
For example look at the field.storage.node.body.yml file.
Link: Persistent Field Storage in Drupal 8
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