Digital permanence

Digital permanence addresses the history and development of digital storage techniques specifically quantifying the expected lifetime of data stored on various digital media and the factors which influence the permanence of digital data. It is often a mix of ensuring the data itself can be retained on a particular form of media and that the technology remains viable. Where possible, as well as describing expected lifetimes, factors affecting data retention will be detailed including potential technology issues.

Since the inception of computers, a key concept differentiating computers from other calculating machines has been their ability to store information. Over the years, various hardware devices have been designed to store ever larger quantities of data. With the development of the Internet the quantity of information available appears to continue to grow at an ever increasing rate often characterised as an Information Explosion. As information stored on traditional media such as hand-written documents, printed books, photographic images and the likes is being replaced by digital files so our social and cultural legacy to future generations will depend more and more on the permanence of digital information.

However, not all this information is worth saving for any length of time; sometimes its value can be very short-lived. Other data, such as legal contracts, literature, scientific studies, are frequently expected to last for centuries. This article describes how reliable different types of storage media are at storing data over time and factors affecting this reliability.

Librarians and archivists responsible for large repositories of information take a deeper view of electronic archives.

Given that individuals' personal data also seems to be growing at an alarming rate, these archiving issues affecting professional repositories will soon be manifest in small organisations and even the home.

Digital computers, in particular, make use of two forms of memory known as RAM or ROM and although the most common form today is RAM, designed to retain data while the computer is powered on, this was not always the case. Nor is active memory the only form used; passive memory devices are now in common use in digital cameras.

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