1. A method comprising: partitioning, in a data storage system, each of a plurality of instances of digital data into a respective plurality of blocks, wherein each instance of digital data is represented by a file identifier, the file identifier referencing each of the respective plurality of blocks; and maintaining a last-reference-check timestamp for each of the blocks within each of the pluralities of blocks such that each last-reference-check timestamp indicates a last time, if ever, the block was validated to confirm that the block was referenced within the system; maintaining a last-validation timestamp for each file identifier such that each last-validation timestamp indicates when, if ever, each block referenced by the file identifier had been validated to confirm that the file identifier referenced the respective block; removing a block from the data storage system when the last-reference-check timestamp associated with the block is earlier than the earliest last-validation timestamp in the system.