|| Preservation Procedure Policy: Define preservation strategies
| Related Guidance Policy
| Functional preservation
| Definition/ Description
|| Describing the organisational elements that can influence the level and type of digital preservation and defining the significant properties (see Chapter 8.5 Significant properties) of the digital material enables the organisation to decide on the proper functional preservation strategy as listed below. The list reflects todays options but technologies may shift rapidly and new technical solutions may emerge.
Migration is a functional preservation strategy that transforms obsolete or soon to be obsolete formats into more viable formats. Migration can also be performed before ingest of digital material into the repository in order to normalize file formats to be able to limit the amount of different file formats in the repository. When an organisation chooses to apply a migration strategy the organisation should decide when the migration should take place. It could either be before ingest (normalization) or when the format is at risk of becoming obsolete (just-in-time migration). If just-in-time migration is decided upon the organisation should watch the development of file formats carefully.
Emulation is a functional preservation strategy that preserves the digital material in the original file format and develops software tools that can simulate the original software needed to access the digital material. When choosing emulation as functional preservation strategy, planning and resourcing of how the organisation will either develop or implement emulation tools in the repository should be carried out.
When doing software/hardware archiving the organisation preserves the original hardware and software to be able to access the digital material in the original environment. If the organisation should decide upon this solution the organisation should considerhow to be able to maintain the archival software and hardware in the long term.
If the organisation deems it to be unrealistic to preserve an interactive collection by emulation or migration, but the organisation still finds the collection to be of such value that certain properties of the collection must be preserved, filming use and content of the interactive collection could be a way of preserving significant properties of that collection. This could be done when dealing with e.g. online multi-player games or interactive websites.
It could benefit the organisation to document in the preservation procedure policies which preservation strategies the organisation would prefer and in what instances a secondary preservation strategy comes into action, e.g. it could be that the organisation chooses migration as its primary preservation strategy but in case of migration not being cost effective or a migration path that preserves the significant properties cannot be found emulation is the secondary choice.
|| Choosing a preservation strategy after defining both organisational and technological factors and significant properties enables the organisation to perform consistent and viable long term functional preservation.
|| The risk of losing either access to the digital collection or comprehensibility of the digital collection is impending if the organisation neither performs functional preservation at all nor performs functional preservation without analysing both significant properties and influential organisational and technological factors beforehand.
| Life cycle stage
|| Preservation Planning, Preservation Action, Transform, Migrate, Access Use and Reuse
|| Depositor: needs to be assured that the organisation ensures continued accessibility of the digital material
Consumer:have an interest in continued accessibility of the digital material
Information Manager: has to decide on functional preservation strategies
Technology Manager/System Architect:have to provide technology solutions for functional preservation
| Cross Reference
|| Bit preservation
Digital object (significant properties)
|| Bayerischen Staatsbibliothek: ”Derzeit wird dabei die Migration in aktuelle, standardisierte und offene Dateiformate als wichtigste digitale Erhaltungsstrategie erachtet, es besteht aber eine grundsätzliche Offenheit gegenüber anderen Maßnahmen (z. B.
National Archives of Australia: “The Archives converts digital records to fully-specified, standards-based open formats (that is, formats whose specification is fully and openly published). The conversion occurs when the records are ingested into the Digital Archive. This is a 'migration' approach to digital preservation that limits the number of preservation treatments applied to each digital record, thereby minimising the risk of altering or damaging the record.” (Source:, [http://www.naa.gov.au/about-us/organisation/accountability/operations-and-preservation/digital-preservation-policy.aspx#section7)
| Control Policy
|| Once the significant properties have been established – for example that the experience of watching a moving image should be the same after preservation, this can be described using the specific measureable aspects of the file & its contents.
An example for a collection of MPEG2 files, the following control policies might set some of the significant properties:
- File format MUST be MPEG2
- The height of the video track >= 586
- Image width of the video >= 720
- Video bitrate >= 6000Whereas an example for a collection of digitized newspapers might include:
- Colour model preserved MUST be TRUE
- Compression type MUST be NONE
| Questions to foster discussions
- Has your organisation defined the significant properties that should be preserved?
- What is your organisation’s approach to digital objects which have been transformed – will the original digital object be disposed of? If not, will an end user be able to choose which version of the digital object they access?
- Has your organisation defined the process for choosing the most effective preservation strategy?
- How does your organisation compare alternative strategies?
- Has your organisation decided upon a strategy for which digital copy/copies an end user can access?