This is a difficult problem. About 20 years ago I did my Master's thesis on
the archival storage of electronic media. My conclusions then were that
electronic media are great for access and outreach in the short term, but
not for archival storage. I have seen no changes in the technologies or
market forces that would cause me to change my conclusion.
The biggest problem is technological obsolescence -- of the hardware to
read the media, and of the software to translate the media to human-
readable form. New formats replace old formats. Operating systems and their
associated software become obsolete at an incredible rate.
There is also the problem of the media itself often being fugitive
(delaminating or deteriorating CD-ROM or DVD-ROM disks, the deterioration
of magnetic data over time, etc).
Example: How difficult (and expensive) would it be today for you to read a
VisiCalc spreadsheet saved on an 5.25-inch format floppy disk drive? You
need a disk drive to read the disk, the data on the disk has to still be
good, and you need a computer with an operating system that can run a
compatible version of the Visicalc software in which the spreadsheet was
The costs of constantly upgrading obsolete technologies is too great to
rely upon contant upgrading to maintain access to the material.
Example: How much 1960s-era reel-to-reel videotape has been or will be lost
to history because there are so few machines that can read it and it is so
expensive to convert to forms we can read today?
A further consideration is the possibility that social upheaval or collapse
will elmininate our successor's access to any technology capable of
translating the data to human-readable form.
My conclusion is that data preservation for archival time periods (hundreds
of years) requires that the data be in a form that requires little or no
technological translation to be human-readable.
* Paper print-outs on acid-free paper
* Sound recordings to grooved phonograph records (a low technology society
could possibly jury rig a machione to play a grooved record. A machine to
read magnetic tape? Not likely).
* Audio tapes should be transcribed and printed on acid-free paper.
* Motion pictures (whether originbally shot on video or film) on mylar-
backed silver halide emulsion film.
* Color motion pictures separated a-la 3-negative Technicolor if color is
important, or prints using pigment-based color technology such as
Kodachrome. I think the technology to do this is now obsolete.
* Digital photographs printed with pigment-based inks on archival paper.
* Print out databases, spreadsheets, etc., onto acid-free paper in formats
and using fonts that can be scanned and OCR'd.
You need a three-phased strategy:
* Keep and maintain working examples of all machines and software for the
forms of technology you must be able to access from the original media.
* Attempt to keep up with technological innovation and have a planned
process for continually upgrading your electronic data so it is accessible
with whatever technology is current.
* Convert, wherever possible, the informational content of the electronic
data to a human-readable form.
Budgetary concerns will ultimately mean we will lose a huge amount of data.