Method and apparatus for managing data in a distributed data storage system, such as but not limited to a cloud computing environment. In some embodiments, snapshots of a data set are uploaded from a source storage subsystem to a cloud store, along with intervening difference information volumes (DIVs). The DIVs are data structures that identify a set of updated data blocks that have been changed by the source storage subsystem between each successive pair of the snapshots. A reader subsystem requests and uses the latest DIV to request the latest set of changed data blocks from the cloud store, and uses the latest set of changed data blocks to update a previous snapshot to generate a copy of the most recent snapshot. The source and reader subsystems can comprise Internet of Things (IoT) devices, client devices, edge computing devices, etc. from different vendors and which utilize different protocols.