Communications of the ACM
Communications of the ACM
Inside Risks: Bit-Rot Roulette
It's obvious that our modern society is becoming immensely dependent on stored digital information, a trend that will only increase. Aspects of our culture that have routinely been preserved in one or another analog form are making transitions into the digital arena. Consumers who have little or no technical expertise are now using digital systems as replacements for all manner of traditionally analog storage. Film-based snapshots are replaced by digital image files. Financial records move from the file cabinet to the PC file system.
But whereas we now have long experience with the storage characteristics, lifetimes, and failure modes of traditional media such as newsprint, analog magnetic tape, and film stock, such is not the case with the dizzying array of new digital storage technologies that seem to burst upon the scene at an ever-increasing pace. How long will the information we entrust to these systems really be safe and retrievable in a practical manner? Do the consumer users of these systems understand their real-world limitations and requirements?
From magnetic disks to CDs, from DVD-ROMs to high-density digital tape, we're faced with the use of media whose long-term reliability can be estimated only through the use of accelerated testing methodologies, themselves often of questionable reliability. And before we've even had a chance to really understand one of these new systems, it's been rendered obsolete by the next generation with even higher densities and speeds.
Even if we assume the physical media themselves to be reasonably stable over time, the availability of necessary hardware and software to retrieve information from media that are no longer considered "current" can be very difficult to assure. Have you tried to get a file from an 8-inch CP/M floppy recently? There are already CD-ROMs that are very difficult to read because the necessary operating system support is obsolete and largely unavailable.
Of course technology marches onward, and the capabilities of the new systems to store ever-increasing amounts of data in less and less space is truly remarkable. A big advantage of digital systems is that it's possible, at least theoretically, to copy materials to newer formats as many times as necessary, without change or loss of dataa sort of digital immortality.
But such a scenario works only if the users of the systems have the technical capability to make such copies, and an understanding of the need to do so on an ongoing basis. While it can be argued that the ultimate responsibility for keeping tabs on data integrity and retrievability rests on the shoulders of the user, there has been vastly insufficient effort by the computer industry to educate consumers regarding the realities of these technologies.
Moreover, when a digital medium fails, it frequently does so catastrophically. The odds of retrieving usable audio from a 40-year-old, 1/4-inch analog magnetic tape are sometimes far higher than for a digital audio tape only a few years old and stored under suboptimal conditions. Digital systems have immense capacities, but their tight tolerances present new vulnerabilities as well, which need to be understood by their often mostly nontechnical users.
Many consumers who are now storing their important data in digital form are completely oblivious to the risks. Many don't even do any routine backups, and ever-increasing disk capacities have tended to exacerbate this trend. The belief that "if it's digital, it's reliable" is taken as an article of faithan attitude reinforced by advertising mantras.
We need to appreciate the viewpoint of the increasing number of persons who treat PCs as if they were toasters. The design of OS and application software systems doesn't necessarily help matters. Even moving files from an old PC to a new one can be a mess for the average consumer under the popular OS environments. Many manufacturers quickly cease fixing bugs in hardware drivers and the like after only a few years. It's almost as if they expect consumers to simply throw out everything and start from scratch every time they upgrade. The technical support solution of "reinstall everything from the original installation disk" is another indication of the "disposable" attitude present in some quarters of the industry.
If we expect consumers to have faith in digital products, there must be a concerted effort to understand consumer needs and capabilities. Hardware and software systems must be designed with due consideration to backward compatibility, reliability, and long-term usability by the public at large. Marketing hype must not be a substitute for honest explanations of the characteristics of these systems and their proper use. Failure in this regard puts at risk the good will of the consumers who hold the ultimate power to control the directions that digital technology will be taking into the future.
©1999 ACM 0002-0782/99/0300 $5.00
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