In this section
Organisational Activities - Access
There has always been a strong link between preservation and access. The major objective of preserving the information content of traditional resources is so that they can remain accessible for future as well as current generations.The link is more explicit in the digital environment in that decisions on how to provide access and how to preserve a digital resource should be made, ideally, simultaneously. As well as the timing of decisions regarding preservation and access, there is also the fact that there is little point in preserving either the container or the bit stream of digital resources.To preserve access to them is also the key objective of digital preservation programmes but requires more active management throughout the lifecycle of the resource before it can be assured.While there is a strong link between preservation and access in terms of the overriding objective of a digital preservation programme, there is also a need to make a clear distinction between them.There may be a combination of technical, legal, and pragmatic reasons to separate the access copy from the preservation copy.This section looks at some of the implications for preservation which may need to be considered when developing an access strategy.
Storage and security
There needs to be both system and physical security if access is to be preserved over time. If the access copy is the only copy of a digital resource, then the danger of loss from theft or damage is clearly very high. In some instances, for example if large quantities of heterogeneous digital resources are being deposited with an institution, a pragmatic decision may have been made to maintain a single copy. If this approach is taken a risk assessment needs to be undertaken consisting of some of the following questions:
- Is it possible to obtain another copy of the resource from another source at any stage in the event of loss or damage? If No, make backup copy.
- Has a legal undertaking been made to preserve the resource? If Yes, make backup copy.
- Is the informational content in the resource rare or unique? If Yes, make backup copy.
See also Acquisition and Appraisal and Storage and Preservation.
There are two main options for acquiring digital resources from external sources:
Via either purchase or legal requirement to deposit.This model is almost exactly analogous to the traditional model, except that additional negotiations regarding access and preservation need to be undertaken. Questions here relate to what access conditions have been permitted by the owners of the data.The ease with which digital resources can be copied and networked can be both a spur and an inhibitor to access as owners of the data seek means of ensuring unauthorised access is not permitted. If responsibility has been taken to preserve the resource and the resource is subject to copyright, it may be necessary to restrict access either for a defined period of time and/or to standalone PCs.There is much debate on the most appropriate means of adapting legal frameworks developed for traditional materials to the digital environment.This handbook is primarily concerned with encouraging thought to be given to how to manage access sanctions which might be imposed, not whether or not they should exist.
License digital content for an agreed period of time.This is an increasingly prevalent model and one which is well suited to the digital environment where access is not dependent on physical custody. However, there are clearly issues regarding sustained access with, to use Ann Okerson's phrase, "the possibility of uncoupling ownership from access, the material object from its intellectual content" (Okersen 1992). Much work has been done to try to streamline licenses, bringing obvious administrative benefits for both publishers and institutions. Model licences, such as the one developed by NESLI for electronic journals, state that publishers must continue to provide access to material previously paid for if a subscription is cancelled. However, it is important to be aware that, even when a supplier agrees to the concept of "perpetual access" this is not completely synonymous with digital preservation, though it does at least provide greater assurance of access for the foreseeable future (see also Preservation Issues and Rights Management).
Depending on current and anticipated levels of use, it may be more practical to have copies stored offline, nearline, or online.What policies and procedures need to be in place to decide which of these is most appropriate, and how the resource can be preserved regardless of where it is stored?
The large file sizes associated with uncompressed formats may make access time unacceptably slow. Similarly some formats may be more suited to presentation and therefore access but not necessarily appropriate for long-term preservation.