Or, a combination of the index card system and document snaps in Evernote. This section in Ryan Holiday’s article definitely made me want to have a digital backup:

My house recently got robbed and I was so terrified that someone took it, you have no idea. Thankfully they didn’t. I am actually thinking of using TaskRabbit to have someone create a digital backup. In the meantime, these boxes are what I’m running back into a fire for to pull out (in fact, I sometimes keep them in a fireproof safe).