[nitrogen]

I haven't read any papers about this, so this is just a first speculative guess that I will update if/when I learn more:

I suspect nodes ask one another to perform computations on random subsets of very large amounts of data. Since the subsets requested would be random, nodes can't predict the requests and thus have to store all the data. The data would then be augmented with the consensus results of these computations, so that future computations would be able to reference them.