From the retrieval times they are giving, it seems plausible that they could be only booting the servers 5 or 6 times a day, to run the upload and retrieval jobs stored in a buffer system of sorts. Having the servers turned off for the majority of the time would same an immense amount of power, although I wonder about the wear on drives spinning up and down compared to being always on.

Any other theories on how this works on the backend while still being profitable?