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Data Storage and CD-R Longevity

What is the best way to archive one’s images? I have been asking myself that and I imagine many of you are wondering the same thing. With all the time and effort invested in scanning and retouching photos, not to mention all those digital camera images that you may be accumulating, how do you make safe, stable backups and get all those gigabytes off your hard drive?

Well, the obvious solution these days is recordable CD or CD-R disks. Forget about rewriteable CD-RW disks... they are not designed to have the same archival stability as a good CD-R disk. We want the best available stability for our data, right? So, the next question is... are there differences in quality between brands of blank CD-R disks? You bet!

Many inexpensive CD-Rs have a very thin to nonexistent protective coating on the top of the disk. Really cheap CD-Rs have been known to essentially disintegrate even in "archival" storage as the CD-R's data layer starts de-laminating from the main plastic substrate of the CD-R. This effect can be accelerated if a cheap CD-R is exposed to additional heat or humidity. Writing on the top of the CD-R with a felt pen has also been known to cause damage to cheap CD-R disks. Over the course of a few months or years felt-pen ink could potentially leach through the top surface to the actual data layer and cause read errors.

High grade CD-R disks such as the original Kodak Gold, Kodak Ultima or the current Fuji CD-R disks have a fairly thick lacquer overcoat on their top surface. This is what Kodak meant with their old "Infoguard Protection System" slogan for their CD-R disks - essentially they were referring to the thick top surface coating they were using. This coating acts to protect the thin, fragile organic dye layer that is actually the data storage substrate of the CD-R. Again, many cheap CD-R disks (no-name bulk disks that cost $0.50 each or less for example) often have essentially no protective overcoat and the slightest scratch, scuff or felt pen bleed through the top of the disk could cause problems or even render the disk unreadable. Many people don't realize that the organic dye data layer that is written to by the CD burner in actually on the top of the CD and not embedded within the plastic. This is why disks without a thick clear-coat are so easily damaged.

Today, Fuji CD-R disks have a heavy top surface clear-coat and their longevity is on par with the Kodak Ultima disks which, by the way, Kodak discontinued on January 24, 2002. In fact, I believe Kodak has stopped manufacturing CD-R disks altogether. Internal testing at Fuji rates their own CD-R disks to have a 70-100 year life expectancy - similar to the Kodak Ultima but less than the original Kodak Gold disks which, if I remember correctly, were rated for a 100-200 year life. Fuji CD-R disks are what we are stocking at Beau Photo these days.

As long as you have a high quality CD-R, felt-pen bleed should not be a problem. I have some Kodak Gold disks from early 1997 which have been written on with a felt pen and so far I have not had any problems reading them. Perhaps more surprisingly, I also have a few less expensive Verbatim and Sony disks from 1997-1998, which probably have a much thinner over-coat, but they also still seem to be all right (fingers are crossed for these) despite being marked on with a felt pen. I have heard from someone recently though, who has had problems reading some 2-3 year old “el-cheapo” no-name CD-R disks, and the feeling was that felt pen bleed may have been the culprit in that case.

My opinion, for what it’s worth, is that for the best long term durability, DVD-R disks may be the way to go at this point. They have the same resistance to deterioration (80-100 year life expectancy) as the best current CD-R disks and since the recordable data layer is actually sandwiched between two layers of plastic they are far less prone to damage from scratches and are essentially impervious to things like felt marker bleed etc.

A few more pointers:

1) If you are really paranoid about your data, create a second duplicate CD-R for every one that you burn and keep it in secure, "off-site" storage. That way if there is a disaster (a fire for example) or you just damage a CD-R disk due to careless handling, you'll be able to still retrieve a backup.

2) Even if a CD burn verifies correctly, I would always double check a CD-R (or DVD-R) by opening a random sampling or files using your computer's regular CD-ROM drive (if it has one). I have occasionally seen a CD burner verify a burn but then the disk has errors when reading in a normal drive. This is less of a problem these days because CD burners, CD-ROM drives and blank CD media are all getting so much better. In fact, this has not happened to me for a number of years now.

3) As mentioned, don't rely on CD-RW disks for long term archiving! They are simply nowhere near as reliable or durable as a high grade CD-R. Plus... they are more expensive as well.

4) And lastly, for the really paranoid, take your existing CD-R collection and start burning DVD-R disks! They will likely be more durable and since they are a newer "standard,” they should be around and "readable" further into the future. In another 10 years we all may be storing many gigabytes of data on small sugar-cube sized holographic memory cubes (IBM has had working prototypes for years now - see links section) and who knows, maybe computers won't even be able to read CD-ROM or CD-R disks anymore!

We all have to make a conscious effort to continually upgrade all of our important data, scans etc. onto newer and more current storage media as technology changes. If your great great grandchildren decide to look and some photos and come across a CD-R disk that you've burned... do you think the computers of their time will still be able to read them? How many computers built today can still read a 5-1/4 inch floppy disk? Long term data storage in today's society is a growing problem and people are just starting to wake up to the realities. I believe Scientific American had an article a few years ago which discussed these concerns, and what became quickly obvious was how tenuous current methods of digital storage are in comparison to the archaic methods of pen & paper or printed books.

Yup... shooting real film still has its benefits. To view, simply hold your film up to a light source and look at it with your own two eyes - no technology required! Okay, maybe a loupe would come in handy...

Mike Mander
Beau Photo Supplies
November 2002

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Links of Interest

CD-R and DVD-R Information

Holographic Memory Storage

Long Term Data Archiving

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