Data Rot II

Following up on my post about data rot, John C. Dvorak has his own issues and solutions for handling data rot:

How long will a DVD last? This always worries me, so I back up most of my writings and photos on both DVDs and two hard disks. I’m paranoid owing to bad experiences with machines crashing, drives blowing up, and old CD-ROMS becoming unreadable. I ran into a cache of 5.25-inch floppies recently and only half were readable. I’m not sure what was on the other disks and what I might have lost. These disks are from the mid-1980s, so they are 20 to 25 years old and failing.

Most of the old 1X CD-Rs that I burned in the 1990s are failing. Back then we were told that these discs would last 40 years with no problem. By my calculations we were told wrong. Now when I have critical data, I turn to the expensive, specially formulated DVD-R and CD-R Archival Grade discs from Verbatim. They cost about $1 each! And apparently there are special materials inside, including a gold reflective layer to prevent corrosion and a hard-coat plastic. These are nice discs and are supposed to last 100-plus years.

What you have to also note nowadays is that most of the normal 25-cent-or-cheaper media is now manufactured all over the place, and all the brands are jobbing out too much. The exact same brand of disc could be made in China, India, or Japan. It’s a mess with inconsistent quality. Most people agree, though, that the two highest-quality brands are Verbatim and Taiyo Yuden. Taiyo Yuden has an interesting product with its unusual “Watershield” printable DVD; inkjet printing on the label seems to be impervious to water and won’t smudge if gotten wet. You pay for the quality, though, at about 60 cents per disc.

I think there are three things to be aware of when archiving data:

  • How long does the medium lasts? This means making fresh copies of the data at regular intervals, from CD to CD, from DVD to DVD, from hard disc to hard disc, whatever. Mediums degrade, get damaged, seize up, etc…
  • Do I have the gear to read it? This means copying data from 8″ floppies to 5 1/4″ floppies to 3 1/2″ floppy, etc… The gear you used to create the copy may no longer be available, supported, usable.
  • Do I have the software to decode this? This means transcoding the data from one format to another as formats are no longer supported. It might be tempting to keep the software to decode older format around but that means keeping older gear and support software around too, which run against what I have suggested above.
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