At a recent computer club meeting, someone asked, “What is the best way to save personal data?” The question was not about backing up data, but was about archiving valuable data sets for long times — at least tens of years. This provoked a discussion of the physical lifetime of writable CDs and DVDs. If the goal is to archive data to last for an indefinitely long time, then normal CDs and DVDs will fall short since both will develop problems over a period of years unless one spends some big bucks on special archival discs.
However, physical lifetime was not what interested me. If one wishes to archive as opposed to simply saving, then consider the fact that I have in my possession images of my family that have been stored for over 100 years and are easily accessible by anyone who is interested. Simply look at the photos that my great-grandparents took on early Kodaks or even earlier tintypes. On the other hand, I also have some Apple ][ floppy disks that someone, somewhere, might be able to read, but I cannot, and I have a roomful of computers. Some of them contain pictures.
Floppy disks of all sizes had a good, but short, run. CDs are still around, but fading quickly. The re-writable ones flowered briefly. How long do you think DVDs will last as a product? Does anyone use re-writable DVDs?
I have a CD/DVD holder that has storage space for 120 discs. At one time, it was nearly full. I had an array of CDs from Corel with images and a collection of art from various museums, amongst other things. Finding clip art is now easier and quicker by searching on the Internet. Many museums have excellent online sites with guided tours and discussions. Even my four-CD set of recordings of bird calls is largely neglected simply because it is easier and more informative to look online. For instance, suppose you wanted to know the call of the yellow-bellied sapsucker. You could sort through the CD holder, find the right disc, and load it, or you could Google on "bird calls yellow-bellied sapsucker" and get this bird video on YouTube. Not only do you hear the bird, but you see a short video of it doing its thing. As good as either my Audubon or Peterson field books are, they cannot compete with a video. The written attempts to characterize bird calls are crude at best. So what use is my huge CD holder?
The rub comes when we consider that my Peterson book is more than 50 years old and is still relevant. 50 years from now, I doubt anyone will be able to access that YouTube video of a yellow-bellied sapsucker. Whatever data sources are available then will likely be better, and maybe operate in an enhanced reality format. Maybe we will also be enhanced -- those of us who are still around.
How should you archive photos and videos? Photographs and motion picture film certainly can survive many years (although finding a projector might be a problem similar to attempting to read Apple ][ disks). But if your precious memories are digitized and stored on a hard drive, you had better have copies on other media in other places also. That will protect you from loss by disaster, but it will not protect you from loss by obsolescence.
Good money can be made digitizing images, converting VHS and 8 mm film to MP3, and updating LP collections to the digital age. But the process never stops. The very reason we need to convert VHS is that it had a finite logical lifetime regardless of how long the physical tape could be stored. By the same reasoning, the DVD that you put the VHS onto will also become obsolete and require another conversion to whatever comes next. In fact, I have several videos on a flash drive, and I prefer it to getting out DVDs and dealing with the jewel cases, which always seem to have a shorter physical lifespan than the disc itself.
What is the best way to store data? My wife's mother emigrated from Ohio to California in 1920 with a carload of young friends. She kept a personal diary of the trip, which we transcribed and made into a modern book complete with the black and white pictures she took. So now the personal data exists in the original, easily accessed, notebook and several transcribed and bound copies distributed to family members. But it also exists in digital form on the computer, which I am currently using to write the piece. Which is the best storage method? The answer is obvious: it depends. I can search the digital form for key words easily, but a handwriting expert could obtain information from the original that I am oblivious to when reading a digital version.
If you think these storage considerations are difficult, think of the task scientists have to come up with when designing a way to keep radioactive waste from being a hazard. Even engraved concrete erodes over such a long time. Keeping data safe for an equally long period of time has its own set of seemingly impossible hurdles to bound.
Most of us would be comfortable with archival storage that is secure for at least a human lifetime or two. Beyond that, it is not our problem. Other than printing with real ink on acid-free paper or photographing on silver-based film, I do not think any of the current methods meet that standard. (Inkjet dyes fade rather quickly; sublimated dyes last longer. Neither is as good as old-fashioned ink.)
For less important things, keeping multiple copies of data on separate devices is good. I use normal hard drive backup augmented with ad hoc storing on a flash drive and the cloud. Occasionally I still burn a CD or DVD, particularly for restoring systems, but even that function can be replaced with a USB drive on most computers.
So what is the best way to store or archive data? Well, it depends...