Illustration by Jørgen Stamp digitalbevaring.dk CC BY 2.5 Denmark
Introduction
Many organisations will have large amounts of data stored on legacy media, such as magnetic and optical media, and data will continue to be received on old carriers. Ultimately, the best long-term strategy for the preservation of the data will be migration to file-based storage and active management thereafter (see Storage section). Often the original media will continue to be preserved alongside this, so it will be necessary to understand their preservation and storage requirements. For organisations with large collections of legacy media, understanding the risks facing each media type will also help with prioritising collections for migration and application of digital forensics tools and methods will also be helpful (see Digital forensics section).
For the preservation of magnetic and optical media, two aspects need to be considered - the media itself and the hardware and software needed to interpret it. In some cases the second aspect will be the most challenging. As the popularity of a media format declines, the manufacture of hardware ceases and becomes more difficult to procure and maintain.
Preserving legacy media
In most cases, the simplest way to mitigate risks with storage media is to transfer all content into a managed storage system. This means that the content can be managed without reference to the original storage medium. This would probably be adequate for the vast majority of digital content requiring preservation. However, there may be a few instances where it is necessary to retain the original media carrier in some way. In some cases, the storage medium could simply be retained as an artifact, with no expectation of long-term access, e.g. where it forms part of a hybrid collection or has some kind of value by association. (e.g. part of the collections of a prominent author). However, where continued access to the content is required, careful thought needs to be given to how it could be accessed in the future.
One thing that we do know from experience is that digital storage media types change frequently over time. For example, the previous version of this handbook contained an overview of magnetic and optical storage media and provided estimates of the lifetimes of selected storage media types that were popular in the mid-1990's (a digital preservation handbook written in previous decades would presumably have included assessments of punched cards and paper tape). Given current trends in storage technology, it is perhaps better now to provide a framework that supports the ongoing evaluation of storage media, which might now include flash memory sticks or external hard-drives. One such framework has been provided by The National Archives (Brown, 2008). This uses a scorecard approach, measuring selected storage media against six criteria:
- longevity (e.g., proven operational lifetimes)
- capacity
- viability (e.g., in terms of retaining evidential integrity)
- obsolescence
- cost
- susceptibility (e.g., to physical damage and to different environmental conditions).
In practice, however, these kinds of assessment can only get you so far. There is a growing body of evidence that suggests that variation in manufacturing quality also plays a major role in media longevity (Harvey, 2011). That is why, in the end, digital preservation normally depends upon the transfer of content from media into a managed storage environment.
Resources
Selecting storage media for long-term preservation, TNA Digital Preservation Guidance Note 2: August 2008
https://www.nationalarchives.gov.uk/documents/selecting-storage-media.pdf
This document is one of a series of guidance notes produced by The National Archives,giving general advice on issues relating to the preservation and management of electronic records. It is intended for use by anyone involved in the creation of electronic. It provides information for the creators and managers of electronic records about the selection of physical storage media in the context of long-term preservation. Note guidance is as of August 2008. (7 pages).
Care, Handling and Storage of Removable media, TNA Digital Preservation Guidance Note 3: August 2008
http://www.nationalarchives.gov.uk/documents/information-management/removable-media-care.pdf
This document is one of a series of guidance notes produced by The National Archives,giving general advice on issues relating to the preservation and management ofelectronic records. It provides advice on the care, handling and storage of removable storage media. Note guidance is as of August 2008. (10 pages).
You've Got to Walk Before You Can Run: First Steps for Managing Born-Digital Content Received on Physical Media
http://www.oclc.org/content/dam/research/publications/library/2012/2012-06.pdf
A step by step guide about getting digital born material off of various physical media. It focuses on identifying and stabilizing your holdings so that you'll be in a position to take additional steps as resources, expertise, and time permit. The POWRR project document Resources for Technical Steps (3 pages) adds additional resources for some of the steps. (7 pages).
Kryoflux: Commercial tool for reading floppy disks
KryoFlux is a USB-based device designed specifically to acquire reliable low-level reads suitable for software preservation. This is the official hardware developed by The Software Preservation Society,
Digital Preservation Management: Chamber of Horrors
http://dpworkshop.org/dpm-eng/oldmedia/disks.html
Some examples of obsolete and endangered disks.
Lost Formats
http://www.experimentaljetset.nl/archive/lostformats
Web page from the Lost Formats Preservation Society with a very nice overview of silhouettes of the shapes to allow quick identification and key brief history and features such as dimensions and storage capacity. All silhouettes shown as same size rather than to scale. Last major update appears to be c.2008 but content is still valuable for all but the most recent formats.
Museum Of Obsolete Media
http://www.obsoletemedia.org/category/format/
Great resource covering a very wide-range of obsolete audio, video, data, and film storage media. You can browse the categories or the Gallery and Timeline. Particularly good if you know what you are looking for and derived mostly from the relevant Wikipedia entries.
Case studies
A Fistful of Floppies: Digital Preservation in Action
https://ischool.uw.edu/sites/default/files/capstone/posters/JStanley_Capstone_Landscape.pdf
The University of Washington Library system currently holds a small collection of electronic thesis and dissertation (ETD) accompanying materials from the late 1980's to 2011 on floppy disks and CD-Rs. These materials will soon reach or have already exceeded the limit of their expected lifespans. This 2015 project looked at the digital preservation possibilities for this collection of materials using digital forensics as a model.(1 page).
Enford, D., et al 2008, Media Matters: developing processes for preserving digital objects on physical carriers at the National Library of Australia, Papers from 74th IFLA General Conference and Council
http://archive.ifla.org/IV/ifla74/papers/084-Webb-en.pdf
The National Library of Australia had a relatively small but important collection of digital materials on physical carriers, including both published materials and unpublished manuscripts in digital form. The Digital Preservation Workflow Project aimed to produce a semi-automated, scalable process for transferring data from physical carriers to preservation digital mass storage, helping to mitigate the major risks associated with the physical carriers. (17 pages).
Digital Preservation Planning Case Study
Presentation on getting started with digital preservation planning, including scoping, risk assessing and prioritising your collection (including legacy media examples), and staff roles and responsibilities. 2013 (20 pages).
References
Brown, A., 2008. Selecting storage media for long-term preservation. TNA Digital Preservation Guidance Note 2: August 2008. Available: https://www.nationalarchives.gov.uk/documents/selecting-storage-media.pdf
Harvey, R., 2011. Preserving Digital Materials 2nd edition. De Gruyter Saur.