1. Create repica set (Primary, Secondary, Arbiter) 2. Insert several documents to (e.g.) test collection. 3. Stop Secondary server, run it offline and remove all documents from test collection. 4. Run Secondary and wait replica set sync is completed. 5. Stop Primary and remove all it's data. 6. Run Primary and wait replica set sync is completed. Result: there is one document (the one that was added last) in test collection on Primary server. Expected: test collection is empty.