The golden rule is 3 copies (minimum) for anything of importance to you,
Too true....I have memory sticks (one per subject), and a big external hard drive in a reasonably fireproof stainless steel case which is not immediately near the PC and not visible, either. The external hard drive gets a weekly dump of all files and a monthly True Image. Some docs are stored on google, also. My entire MP-3 music file is also on the car's hard drive, not for security but so I can play it there and gets updated every week. My MP-4 file is on a portable player.
Obsessive ? Maybe.