I was pleasantly surprised when I found that the entire wikipedia backup is only 17.5GB, and easily fits on a 4TB external backup drive. Wikipedia has been an absolutely invaluable resource, and if you want to help preserve this information please use your favorite software and help seed the Wikipedia torrent.
https://en.wikipedia.org/wiki/Wikipedia:Database_download
Everyone should Download Wikipedia
List -> https://meta.wikimedia.org/wiki/Data_dump_torrents#English_Wikipedia