Time Is Not on Our Side: The Challenge of Preserving Digital Materials
Roy Tennant -- Library Journal, 3/15/1999
Digital libraries are sitting on a time bomb. Yes, libraries are already familiar with deteriorating materials, but digital libraries face an even graver threat. While digital library materials do not decay like old paper, they nonetheless may become unusable. And digital librarians have learned that solutions must be different as well.
The nature of the problem
"Preservation," Yale's Paul Conway writes in the report "Preservation in the Digital World," "is the acquisition, organization, and distribution of resources to prevent further deterioration or renew the usability of selected groups of materials." The currently accepted preservation formats are acid-free paper, microfilm, and photographic reproduction. None of these are digital. In fact, there is no accepted format for preserving digital information. Rather, Conway and others discuss preservation strategies rather than formats. Preservation in the digital world, it turns out, has much more to do with long-term institutional commitment than with short-term fixes.
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LINK LIST |
| Center for Research Libraries http://wwwcrl.uchicago.edu/ |
| Conservation Online http://www.palimpsest.stanford.edu/ |
| Conserve O Grams http://www.cr.nps.gov/csd/publications/ conserveogram/cons_toc.html |
| Council on Library Information and Resources (CLIR) http://www.clir.org/ |
| Digital Library Federation http://www.clir.org/diglib/dlfhomepage.htm |
| JSTOR http://www.jstor.org/ |
| Preservation and Access International Newsletter http://www.clir.org/pubs/pain/pain.html |
| Preservation in the Digital World http://www.clir.org/cpa/reports/conway2/ |
| Preserving Access to Digital Information (PADI) http://www.nla.gov.au/dnc/tf2001/padi/ |
| Preserving Digital Information: Final Report and Recommendations http://www.rlg.org/ArchTF/ |
| RGL DigiNews http://www.rlg.org/preserv/diginews/ |
| Statement of Principles for the Preservation of and Long-Term Access to Australian Digital Objects http://www.nla.gov.au/nica/digital/ princ.html |
| A Strategic Policy Framework for Creating and Preserving Digital Collections http://ahds.ac.uk/manage/ framework.htm |
Why? Because preserving digital information is not simply a matter of determining which format will resist physical deterioration the longest -- although that is still one aspect of the problem. The more serious threat is technological obsolescence. Remember 8-track tapes? Technology marches on and leaves previous, outmoded technologies in the dust.
The key publication that outlines the dilemmas of digital preservation and the need for a strategy to deal with the problems is "Preserving Digital Information: Final Report and Recommendations," from the Research Libraries Group (RLG).
This seminal report identifies the need for a migration strategy, so that as each technology reaches the end of its life, any information stored in that system or format can be brought forward into a new format or system. Migration therefore differs from the concept of refreshment, in which data from one deteriorating hard disk, CD-ROM, or tape are copied to another.
As outlined in the task force report, migration strategies can take several forms. One strategy is to change the storage medium, the most extreme solution being to print the item on acid-free paper, thus losing its digital nature altogether. An alternative: change format, i.e., move documents in proprietary word processing formats such as WordPerfect to ASCII or SGML-encoded text.
Central repositories needed
Standards for document formats, data storage, and information interchange are needed to help libraries and archives build effective data migration strategies. Given the specialized nature of this kind of work, as well as the costs to migrate information from one format to another, we may need to cooperate in funding central repositories to take on these tasks.
We already have models of similar kinds of cooperative efforts in organizations like the Center for Research Libraries (CLR), which collects rare items on behalf of a coalition of research libraries, and efforts such as JSTOR, which archives scholarly journals. A central digital archive could be supported by dues or fees from participating libraries and be reponsible for migrating the information it holds to prevent its loss through media decay or technological obsolescence.
The more complex the material...
So far I've allowed you to assume that we are talking mainly about relatively straightforward materials -- digital books, journals, and word processing files. Such mainly textual materials can typically be migrated from one technology to another without a great deal of information loss. For example, many of us can move files from one word processing program to another without much loss of content or context.
But what about much more complex materials that were born digital, such as multimedia presentations? What happens when the hardware and software environment required to run such an item is no longer available? What are the best preservation options for such complex items? We are just beginning to consider how these problems can be solved.
As may be apparent at this point, a viable digital preservation strategy requires institutional commitment and a structure of policies and procedures. "A Strategic Policy Framework for Creating and Preserving Digital Collections," produced for higher education institutions in the U.K., is a useful discussion of some of these issues.
This framework identifies three main stages in the life of a digital resource (creation, management/preservation, and use) and appropriate roles and functions of different stakeholders (funding agencies, libraries and archives, etc.) in preserving the resource. For an example of a specific digital preservation policy statement, see the National Library of Australia's "Statement of Principles for the Preservation of and Long-Term Access to Australian Digital Objects."
Doing the job once
An essential aspect of any preservation program is quality, or the importance of doing the job once and doing it right. This is particularly urgent for digital librarians, since standards for digital preservation are still being formulated. For example, what if you wish to digitize a deteriorating print item? Several years ago you would have probably scanned the item at 300 dots per inch (dpi). Since technology has both improved and dropped in price since then, now you would likely scan it at twice that resolution.
If there is this much difference in how an archival master is produced over just a few years, what does this bode for the long-term? What compromises in quality are we making now that we may regret later? It is just such issues that keep digital preservationists awake at night.
While they are unable to get any sleep, one thing digital preservationists can ponder is how things have changed. With print materials, preservation is an endgame. Typically, you don't have to think much about preservation until the book begins to crumble, or the binding starts coming apart. With digital material, everyone wants a commitment up front that you will keep this material around for the forseeable future.
Within minutes of announcing the opening of the Berkeley Digital Library SunSITE February 1, 1996, I had a return message from a colleague wondering what commitment we had to preserving the material we were making available. What is it about digital information that turns the preservation process on its head?
Perhaps we need to cultivate an open market for digital information: when a library or archive no longer wants to maintain a particular collection, it announces the availability widely. If no person or organization steps forward to rescue it from extinction, then it probably is not worth saving anyway. After all, although individual libraries should check to see if they have the only copy of a print item before throwing it away, there is no formal mechanism for doing so nor any requirement to do so.
Digital preservation resources
Besides the publications mentioned above, a number of resources can help you explore these issues further. "Preserving Access to Digital Information" (PADI), hosted by the National Library of Australia, points to a number of bibliographies, discussion lists, journals, web sites, and more; the "What's New" section is a good way to keep current. The "Conservation Online" (CoOL) web site is also an important resource, although it covers the preservation of nondigital material as well.
Organizations active in this issue include the Commission on Preservation and Access (CPA) and the Digital Library Federation (DLF), both of which are under the umbrella of the Council on Library Information and Resources (CLIR). Useful publications include the bimonthly "RLG DigiNews," the quarterly "Preservation and Access International Newsletter," and the occasional "Conserve O Gram" from, yes, the National Park Service.
Roy Tennant (
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