A system implements techniques for processing data across multiple layers. In some embodiments, a distributed data processing system tracks processing states via a monotonic process, whereby each state is irreversibly entered and cannot be entered without a predecessor state being verifiably completed. In some of such embodiments, a multi-layer data storage system tracks and processes data deletions across disparate layers such that a deletion state can be positively deduced from the deletion states of each of the disparate layers.