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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