I had misplaced a(n old) flash-drive for at least a year, and it was in good state when I found it. I suspect flash-drives work best when occasionally used for reading. Writing on a flash drive wears it down and eventually you won't be able to write; reading should still be possible (much like SSD's). But the whole stick might spaz out on you, once it's worn down. Physically damaging the exterior is much more likely (f.i. stepping on it).
Compared to HDD, flash-drives die unexpectedly with few warning signs. So in that sense it might be nice to ensure you have another valid copy somewhere at all times. Only happens after extensive writing or age, so you shouldn't worry too much now.
My burned CD/DVD's usually last. I've had a few fail. Then I'm talking about approximately 3-10 out of 200 over 12 years. Storing them dark is important. Soft cases/wallets are much better than hard cases, which tend to scratch the CD when moved. Also there are some bad brands.
You could zip your files with extra error correcting code. That's a really reliable back-up. Maybe an other option might be making a filesystem with error correcting code, but that might be a hassle.
Last edited by Weapon S; 03-05-2013 at 04:19 AM.