Unless you make a regular habit of taking a USB offsite to a friend/relative or a safe deposit box, then you don't have a good disaster recovery plan.
This is sound advice and the key word here is "regular".
If one has an off-site location, be it a friend/relative's house, a lock-box at the bank, or under the seat of your truck, you need TWO backup disks for each disk of storage, one in the safe place and the other connected to the computer, and switch them regularly; daily would be ideal.
Another safety measure would be to run an Ethernet cable to another building (garage, barn, cellar, tree-house) to a second network-connected computer and let Synchredible mirror everything that is done on the main machine onto the remote backup machine.
One other thing one should have a regular backup of is the operating system of the computer; I use FREE Macrium Reflect for this and it works wonderfully as I have put it to the test. (surely one doesn't have the operating system AND photos and other data on the same disk/drive ??)
Elements 7 ~~~ 64-bit Windows 7
On a poverty-level Kentucky budget, a 24-exposure roll of film would have two Christmases and a summer vacation on it and we might have to wait another six months before being able to afford developing the film.
I still have trouble remembering that it doesn't cost anything to take thousands of pictures; it just almost seems impossible to be true.