Ditto! I recently moved the Calibre library to our server so that it is backed up on a regular basis. Granted, I've also sent all of my non-Amazon books to my Kindle email so that those books are also "in the cloud"... but I feel better knowing that I won't ever "lose" my books.
I like the idea that someone posted about keeping track of the read books in a spreadsheet. I might have to set up a Google file for that so I can get to it with my phone and NC too.
I used to keep an Excel spreadsheet - lost it in a computer near-death. I used Goodreads to re-create it on paper, in an unused travel journal I'm now using to keep track of the books I finish. I figure books take me places so it's appropriate enough, and it even has pockets for pictures that I use to keep things like the info for logging in to my Overdrive libraries, lists of books in a series in order, etc. And I'm happy to be using the journal, which I'd bought when we had an RV that we don't have any more.