Nowadays family pictures, writings and home movies are stored on digital media, under the impression that this personal information will be accessible for a lifetime. However, this is not self-evident. To guarantee the accessibility in the not even so far future, digital data requires active and regular maintenance – contrary to the archiving of analogue media. Even though this constitutes a large challenge for libraries, for them the problem is not insurmountable. But in everyday life, a lot of personal information is in peril of getting lost.

With increased convenience, so it seems, comes a decreased life expectancy.

The benefits of a digital archive are unmistakably large. Electronic files take up much less space than the same amount of information on paper or on other analogue media. At least as important is the much higher availability of the data. Digital information can be copied en masse in a matter of seconds and a document residing in a digital archive can be consulted by multiple people at the same time.

Moreover, if this electronic archive can be consulted via the internet, the information is available day and night, from anywhere in the world. Sharing pictures was never as easy as it is today. At the same time, it’s impossible to damage or steal the original documents (if there are original documents. An electronic archive also has very powerful search and navigation capabilities. Unfortunately, the digital medium has important drawbacks too, which undermine all the advantages.

Physical obsolescence

The first problem is the physical durability of digital data carriers or storage media, which is notably shorter than that of analogue media. Stone, the most ancient information carrier, still has the best life expectancy. It lasts several thousands of years – but it is not in the most convenient archiving format.

If treated well, paper can be kept for at least one hundred years, while good quality paper can be maintained up to 500 years. CD’s and DVD’s have a life expectancy of only 50 to 100 years. With increased convenience, so it seems, comes a decreased life expectancy.

Worse, however, is the life expectancy of (re)writable optical media, like DVD-R and DVD-RW. These are the storage media that people use to save their family pictures, writings and movies. Manufacturers of (re)writable optical discs claim a life expectancy comparable to that of pre-recorded compact discs, but experts say these claims are way too optimistic. Archivists count on a maximum life expectancy of around ten years, comparable to the life expectancy of magnetic tapes like music and video cassettes.

Chances are in twenty years we laugh out as loud with CD’s and DVD’s as we do now with floppy discs.

Rewritable media might resemble pre-recorded digital media, but they are a very different technology. They are decaying much faster and they are extremely vulnerable to environmental conditions like humidity, temperature and even light. If not saved with care, these media can become unusable in just a few years, or even months.

Hard disks and portable media like mp3-players and USB-sticks also have a disappointing life expectancies of less than ten years. Therefore, if you want to keep digital information for a lifetime, you have to copy the data to new discs every couple of years. Archivists and professional photographers are doing that already. They also make two copies: one to use and one to store in optimal conditions.

Technological obsolescence

Unfortunately, the limited physical life expectancy of digital media is not the only challenge for long-term storage of digital information. Even worse is the danger of technological obsolescence. An analogue letter or picture is easy to keep, since data carrier and information are inseparably tied to each other.

To store the information, all you have to do is store the data carrier. To consult a 100 year-old book or photo album, you only have to open it. Not so in the case of a digital file. Here, the data carrier alone does not suffice to consult the information. You do not only have to save the “letter”, but also the machine which is needed to “read” it. (And, of course, you need electricity to run the machine.)

To some extent, the same is true for a music cassette or an LP – you need a music cassette player or a turntable to listen to the recording. In the case of digital information, however, you need more than just a computer. The accessibility of a digital file depends on a certain configuration, a specific combination of hardware and software.

To read an e-mail or to view a digital photo-album, you need a particular e-mail or imaging program, which in its turn is dependent of a particular operating system. This operating system only runs on a certain computer platform. If the e-mail or photo-album is stored on an external storage medium, like a DVD-ROM, you also need a specific reading device. If just one of these components is not present, then the data are not accessible.

To consult a 100 year-old book or photo album, you only have to open it. Not so in the case of a digital file.

The rapid developments in hardware and software threaten to make the life expectancy of the now massively produced digital information extremely short. For example: diskettes, the accepted storage technology during the first half of the nineties, are impossible to read on most laptops today. Digital storage media of 20 years ago (large floppy discs) are unreadable by any computer on the market today.

Chances are in twenty years we laugh out as loud with CD’s and DVD’s as we do now with floppy discs. The storage medium does not even have to change format to become unreadable. Not all DVD-players are capable of reading CD-R’s or CD-RW’s, because their laser beam uses a different wave length. And if it’s not the data carrier that changes, then it’s a standard, a software program or a cable, like the transition from the serial port to the USB.

The computer museum strategy

In libraries, where digital preservation has been a hot topic for some years now, two different strategies are applied to save digital information. The first approach is sometimes called the “computer museum strategy”.

The library stores all the machines which are needed to read the files: not only the successive generations of computers but also the compatible software, storage devices, cables, keyboards, mice, etcetera. This procedure is easy, but far from optimal.

Firstly, after some time you need a lot of space to stockpile all the machines, while the digitalisation process was meant to save space. Secondly, and more importantly, if a machine breaks down, it might be impossible to find spare parts.

The migration strategy

The second strategy is the “migration” of the digital documents to the successive hardware and software platforms. In this case, files are not only regularly transferred to new data carriers (to prevent physical obsolescence) but also to the successive generations of hardware and software. That means every file should be copied to a new format, preferably not to a successive version of the same commercial format (like Word or Outlook Express) but to an open standard like XML, HTML or PDF.

One strategy is to save not only the successive generations of computers but also the compatible software, storage devices, cables, keyboards, mice, etcetera.

With this method, it is not necessary to save the hardware and software on which the documents were made, or on which the emails were received. It is a much more elegant solution that preserves all benefits of the digital medium. The life expectancy of PDF and XML is 50 years or more, and since it concerns an open format, new programs can always be written to open the documents.

The most important drawback of this strategy is that saving digital files is becoming a very time-consuming activity, which can never be completely automated: the user has to decide which documents to save, which name to give them, and where to save them.

The user also has to check whether or not the transformation of the document was successful, because during the migration of the content mistakes can occur (in the worst case scenario a text can become a set of meaningless characters). For a library or a professional archivist department, this is a hell of a job, but it’s not an insurmountable obstacle. For the masses, however, migration is mostly not a realistic option since it would become something of a part-time job.

The printing strategy

For computer-illiterate consumers, therefore, only two options remain. Either they choose, consciously or not, the ‘computer museum strategy’ - for example, my own digital files are distributed among 4 obsolete computers. Or they print out the texts and pictures they really want to keep – like I do, or try to do, with the most important emails and pictures.

The result, I must confess, is confusing. After 12 years of writing, I have built up a small room full of “digital” archives, in the form of paper and machines – with all the advantages of digital archiving gone and with many important files still in danger of extinction.

There were days that I dreamt of digitalizing my paper archive. Now I realize that it would mean first scanning all the documents to be able to search them digitally, and then later printing them to store them for the future, which would not leave me time to do anything else.