Digital preservation is a combination of infrastructure and services which collectively guarantee the availability of the National Library’s digital archive for future generations.
Digital preservation ensure that digital material is archived and preserved exactly as it was received, and that data over time can be read, and understood, as closely as possible to the original expression.
Digital preservation at the National Library is based on the following principles:
- Ensure that digital preservation is done in a sustainable way.
Be deliberate in selecting which files to preserve and in which format. Digital preservation of a file comes with lasting cost implications for the organization. Choose storage technologies that are environmentally friendly and energy efficient. - Use well-documented and open file formats whenever possible.
This increases the likelihood that we will be able to read, understand and utilize the file, now and in the future. Good format choices make it easier to manage the file over time. Proprietary and undocumented file formats can have short and unpredictable life spans. The NLN recommend using the following Preferred file formats. - Preserve the original file.
With future format conversions, there is always a risk that the content will be changed in an undesirable way, either deliberately or through errors in a conversion process. Preserving the original file makes it possible to convert a file again or revert to the original. In this context the original file refers to the originally received file. - Analyze the file.
Generate checksums as early as possible. This enables you to verify whenever needed that the file hasn’t changed. Check and document the file’s condition. Confirm the file type and validate that the content is what it claims to be.
- Maintain sufficient metadata to ensure that the files are identifiable and retrievable.
This information ensures that files can be managed, understood, used, and retrieved in the future, regardless of external conditions. This helps maintain the integrity of the collection.- Technical metadata such as file format, file size, structure, etc. This provides detailed technical knowledge about the file. It strengthens the collection’s integrity and improves the quality of planned preservation activities, such as format conversion.
- Administrative metadata such as the source of the files, how they were created and processed, rights information, and other provenance. This provides knowledge about the origin and history of the files and helps to establish the credibility of the content.
- Descriptive metadata such as plot synopsis, content description, information about creators, credits, etc. These describe the intellectual content of the files and make the content identifiable and retrievable.
- Use a standard for structuring files.
Standardization enables effective exchange of content and metadata in a uniform way, regardless of material type or depositor. It also provides access to documentation and support tools. The NLN uses the E-ARK standard. - Document preservation activities in a standardized way.
This strengthens the collection’s integrity and improves the quality of planned preservation activities. The NLN uses the PREMIS standard. - Files must be readable and understandable in the present.
If a file cannot be accessed today, it is unlikely it will be accessible in the future. This requires monitoring of file formats and playback platforms to implement necessary actions. The NLN recommend keeping an eye on “The Global Bit List of Endangered Digital Species.” - Ensure that the file is stored in multiple copies.
Multiple copies reduce the risk of data loss due to technical or physical incidents affecting individual files. The NLN follows the 3+2+1 principle: 3 file copies, on 2 different storage technologies, with 1 file copy stored at a separate geographic location.