My PLEX disks are backed up every night to a duplicate set in the same box. My laptop and Mrs WmA's laptop do file history backups throughout the day to a Raspberry Pi and these disks are backed up with an Rsync to a duplicate set. Other bits of kit around the place are backed up/duplicated as well (plus I keep all my important docs and things on an Owncloud server). I suppose I really should look at something "off-site" even if it's some ethernet string and an extension running out to the shed.
It's honestly got me thinking, I have an old NAS (liberated from work) with 4.5TB capacity. Currently it sits on my desk and I do periodic backups to it. I'm considering running a network cable to the far loft corner of my garage and sitting it there. OK it's not really offsite, but would stand a much, much bigger chance of surviving either a fire or a burglary.
Well I'm saying goodbye to Virgin cable in a week, so what with all the cable-shuffling maybe I'll actually get round to doing something.