Establishing a reliable technological infrastructure in the face of rapid and ongoing change is a core organizational challenge. Meeting that challenge requires adequate funding, appropriate expertise, systematic monitoring, and an established process for informed decision-making. An organization may not incorporate every technological change, enhancement, upgrade, but it should establish the means to identify essential changes to implement over time that are needed to sustain the digital preservation program.
Many factors can influence the selection of media for long-term digital storage. Weighing those factors against each other for the great variety of media available today can be a complex task. The table that follows shows one approach. In this example, each medium is scored against the criteria on a scale of 1 (does not meet the criterion) to 3 (fully meets the criterion), and a minimum total score of 12 is recommended for consideration. (See Selecting Storage Media for Long-Term Preservation for a description of the selection criteria.)
| Media | CD-R | DVD-R | Zip Disk | 3.5” Magnetic Disk | DLT | DAT |
|---|---|---|---|---|---|---|
| Longevity | 3 | 3 | 1 | 1 | 2 | 1 |
| Capacity | 2 | 2 | 1 | 1 | 3 | 3 |
| Viability | 2 | 2 | 1 | 1 | 3 | 3 |
| Obsolescence | 3 | 2 | 2 | 3 | 2 | 2 |
| Cost | 3 | 2 | 1 | 1 | 3 | 3 |
| Susceptibility | 3 | 3 | 1 | 1 | 3 | 2 |
| Total | 16 | 14 | 7 | 8 | 16 | 14 |
Even with optimal media selection, potential physical damage to all hardware components must be evaluated, acknowledged, and considered carefully and safeguards in terms of equipment, policies and procedures, and expertise must be incorporated.
Furthermore, media selection and hardware integrity are only part of the complex chain of considerations to ensure long-term preservation. Storage media that is physically intact is only useful if the data it contains can be accessed and rendered into a human-readable form. For now, obsolescence is a clear and present danger to digital information, and proactive plans for handling the issue must be a part of any digital preservation program.