After I wrote my original blog on archival CDs and DVDs, a friend on another site wrote that it's possible for even these two forms of back up to fail at the same time. It's a remote possibility, but it can happen. He suggested online storage as another form of backup. While this sounds great in theory, and I'm sure that the best online storage sites will ba around for most of our careers as photographers, and designers; it has it's problems, too. I have heard of sites failing and photographers losing huge portions of their work, but it's probably as safe as any form of backup.
Operating systems change, discs become unreadable, hard drives fail, and online storage goes belly up. The conclusion that I've come to after studying this issue is that we're all going to have to be constantly vigilant about keeping our backup technically current. The form it takes is going to have to be constantly updated and changed. Keeping educated on the best current method for archiving our work and using it is going to need to be an integral part of our workflow.
How many forms of backup I feel the need to use is a decision that I haven't made yet. Right now, I'm sticking with archival discs and a hard drive, but I may decided to check into archiving more of my images online. One thing is clear, two forms of backup are definitely needed, if not three. Any input from those of you who are more experienced in this area would be much appreciated.