Years ago, when I first started using computers, the only method of saving material was on a floppy disk. Either that or print everything you'd written before you closed out for the day. The latter was more reliable. I have TONS of printed manuscripts here, yellowing in boxes, and pretty much useless to me now. But at the time, the hard copies did serve their purpose. Those floppies were about as reliable as the weather. I've never been able to access one when I upgraded to a different computer. Either the computer was unable to read the files, or they were corrupted.
Next came the wonderful innovation of writable CD drives. Yippee! Loved it...until the CD drive stopped working, which has happened to every single computer I've ever owned. In fact, I have my new computer with the beautiful, huge flat screen only because my last computer became infested with viruses and a few other nasties. I had to wipe it out and start over. When I did, I discovered the CD drive wouldn't function. I couldn't install my Word program! So, it was off to Office Depot for another computer. (And by the way, don't fall for their sales pitch about the bundle deal with the huge mail-in rebate. It's a lie. The teeny, tiny fine print clearly states that the rebate doesn't apply to their bundles. Yet the salesman sold me on the deal I bought because of the rebate--and I never got it.)
Finally, we have our flash drive, travel drive, or whichever way the thing is packaged. It's wonderful and compatible with any computer. There's nothing mechanical to stop working. And we can save oodles of material on something about as big as a thumb. Amazing! Everything, evidently, except a synopsis and query letter. They were in my old computer and I thought I'd saved everything to the flash. So I guess no method is perfect unless you remember to use it.There is one more method of saving manuscripts and writing related materials, but it seems a little extreme. An author I know once told me, she started a Yahoo group with herself as the only member. She uploads everything to the files section on the group site. Now there's a thought. Store it out there in cyberspace. With my luck, the World Wide Web would crash.