Dang, that's mind boggling - especially if I keep in mind that a book series like lord of the rings is mere kilobytes if saved as plain text.
Having 86 TB of plain text/source code - I can't fathom the scale, honestly
Are you absolutely sure there aren't binaries in there (honestly asking, the scale is just insane from my perspective - even the largest book compilation like Anna's isn't approaching that number - if you strip out images ... And that's pretty much all books in circulation - with multiple versions per title)