Only the most legal, unpleasant porn.

Make sure you have legally obtained copies of porn if you do this. Unfortunately, it does not seem unreasonable to me that doubly illicit images (copyright-violating porn) could lead to a cause of action against the holder of the hard drive.

That bit I don't get. Why are they happy to upload arbitrary data to their servers unless it's porn?

"US tax dollars paying to store petabytes of porn, news at eleven"