October 2002

Data Extinction

Continued from page 6

By Claire Tristram

Unawakened Demand

Boiling down the specifications for the universal virtual computer into a handful of pages poses technical problems that Lorie believes can be solved. But will they be? Like everything else involving information technology, they won't be until there is enough demand to pay for the development work. By that time, however, many digital things may be past the point of resuscitation. Lorie is the only researcher at IBM with funding to study the universal virtual computer. "I wish I could say I have 20 people working on the problem, but I don't," he says.

Robert Morris, director of the Almaden lab and Lorie's boss, doesn't equivocate. "It's unfortunate, but the reason there's not a huge amount of activity is because there isn't a lot of money in it," he says. "At the moment there are not a lot of people clamoring to solve this problem."

That may change as computer users realize how much has already evaporated. In October 2001 Brewster Kahle, the man behind a project known as the Internet Archive, put up a Web site known as the Wayback Machine, a way for people to search the archive's collection of 10 billion Web pages it had crawled over the previous five years. With 1997-era Web pages in his archive, Kahle is already grappling with preservation questions. Many of the pages suffer from broken links and half-missing text, and whole classes of items-those protected by passwords or payments, for example-aren't archived at all. "We don't know how much we've lost," he says.

Like global warming, the problem of digital preservation is so big that it's hard to grasp. But when a million people are using the Wayback Machine and not finding the digital files they're searching for? Then the problem starts to become real.

"People count on libraries to archive human creativity," Abby Smith says. "It's important for people to know, though, that libraries are at a loss about how to solve this problem." When computer users are saving documents or images, they don't think twice about making them accessible to future generations, she says. "They need to."

Digital-Preservation Proposals

Technique	Description	Pros	Cons
Migration	Periodically convert digital data to next-generation formats	Data are "fresh" and instantly accessible	Copies degrade from generation to generation
Emulation	Write software mimicking older hardware or software, tricking old programs into thinking they are running on their original platforms	Data don't need to be altered	Mimicking is seldom perfect; chains of emulators eventually break down
Encapsulation	Encase digital data in physical and software "wrappers," showing future users how to reconstruct them	Details of interpreting data are never separated from the data themselves	Must build new wrappers for every new format and software release; works poorly for nontextual data
Universal virtual computer	Archive paper copies of specifications for a simple, software-defined decoding machine; save all data in a format readable by the machine	Paper lasts for centuries; machine is not tied to specific hardware or software	Difficult to distill specifications into a brief paper document