Over the years I've backed up my word files on floppies, rewritable CDs, and flash drives, but I've still managed to lose a lot of material as a result of computer crashes. Any backup method is only as good as the person using it. You have to resave each document after each and every little edit or you're not covered.
Let's run it down. Floppies are out of the question. They never were reliable, and these days computers usually don't even have a floppy drive. Writable CDs are good, I guess, but I always had a problem with those as well. On every computer I've owned--and I'm now up to half a dozen--the CD drive has eventually stopped working. I'm now using flash drives, but I understand they are also vulnerable because they can become corrupted.
Back in the very early days of owning a computer, I printed everything. It didn't take long before I was buried under a mountain of partials in hard copy. I printed each time I made a change or added to each document and, after a while, I couldn't make heads or tails of any of it because the sheer volume of version 1, 2 , 3 etc. became overwhelming. And let's not forget the cost of paper and ink for all that printing.
So, what's the answer?
Many writers set up a Google or Yahoo email account and email their manuscripts to themselves. But I foresee the same old problem with this. You would have to be super diligent and email the ms. each and every time you make a change to the text.
I know how heartbreaking it is to lose an entire manuscript or even multiple partials, not to mention pictures and other sundry items, in a computer crash. Just the other day, a dear friend and fellow writer asked me if I perchance had any of her old manuscripts on my computer from when we used to critique together. Sadly, I had to say I didn't. Those critiques were two computers and several years ago. I feel so bad for her. She's lost everything she didn't have in hard copy.
If anyone has a tried and true backup method that I haven't mentioned, I'd love to hear about it.