Table 1
USGS modified Levels of Digital Preservation. Derived from Library of Congress, National Digital Stewardship Alliance: Version 1, February 2013. [NARA, National Archives and Records Administration].
| ELEMENT | LEVEL ONE | LEVEL TWO | LEVEL THREE | LEVEL FOUR |
|---|---|---|---|---|
| Storage and Geographic Location | – two complete copies stored physically separate from each other – Transfer the digital content from temporary media into an established storage system –Managed storage system in place | – three complete copies – At least one copy in a different geographic location (offsite locations must follow NARA 1571 guidelines (NARA 2002)) – Document the storage system and storage media | – At least one copy in a geographic location with a different disaster threat (e.g. hurricane area versus an earthquake area) – Maintain an obsolescence monitoring process for the storage system and media | – At least three copies in geographic locations with different disaster threats – Implement a comprehensive plan that keeps files and metadata on currently accessible systems and media |
| Data Integrity | – Verify checksums on ingest, if provided- Create checksums if not provided- Virus check all content | – Verify checksums on all data ingest – Use read only procedures when working with original media | – Verify checksums at fixed intervals – Maintain logs of checksums and supply audit information on demand – Maintain procedures to detect corrupt data – Virus check all content | – Verify checksums of all content in response to specific events or activities – Maintain procedures to replace or repair corrupted data – Ensure no one person has write access to all copies – Create, store, and verify a second, different checksum for all content |
| Information Security | – Identify who has authorization to read, write, move, and delete individual files – Limit authorizations to individual files | – Document access restrictions for content | – Maintain logs of who performed what actions on files, including deletions and preservation actions | – Perform audit of logs |
| Metadata | – Inventory of content and its storage location – Ensure backup and physical separation of inventory information – Adhere to current USGS metadata standards | – Store all relevant database management information – Store information describing changes to the structure or format of the data, including time of occurrence – Provide access to all forms of the metadata | – Preserve standard technical, descriptive, and preservation metadata | – Same as Level 3 |
| File Formats | – Encourage the use of a limited set of documented and open file formats, codecs, compression schemes, and encapsulation schemes | – Inventory the file formats in use | – Monitor file format obsolescence issues | – Perform format migrations, emulations (a virtual instance of a previous operating system or procedure) and similar activities |
| Physical Media | – Inventory all physical media utilized including hard disks. | – Develop a plan to utilize trade studies to evaluate medias suitable for USGS purposes. – Begin to transition away from all media utilized that are 10 years or more in age. | – All non-recommended media have been properly disposed of following transition activities. | – Base all media choices on trade studies. – All information is migrated from an older media to a newer media every 3 to 5 years including hard disks. |
Table 2
The table matrix shows the criteria established by other organizations to evaluate. The cells indicate the categories addressed by the various criteria examined.
| FMM | DCC | UFMS | DSA | ISO 16363 | FSPAC/NDSA | DSA/WDS | |
|---|---|---|---|---|---|---|---|
| Organizational Structure, Mandate, Financial Resources | X | X | X | X | |||
| Governance Policies | X | X | X | X | |||
| Lifecycle Management, Preservation | X | X | X | X | X | X | X |
| Accessibility | X | X | X | X | X | X | |
| Quality Assurances | X | X | X | X | X | X | |
| Risk Management | X | X | X | X | |||
| Metadata | X | X | X | X | X | X | X |
| Certification Offered | X | X | X |
[i] Table source abbreviations used:
FMM = Federal Maturity Model.
DCC = Digital Curation Centre (United Kingdom).
UFMS = A Unified Framework for Measuring Stewardship (NOAA).
DSA = Data Seal of Approval.
ISO 16363 = International Standards Organization No. 16363.
FSPAC/NSDA = USGS Fundamental Science Practices Advisory Council/National Digital Stewardship Alliance.
DCC and DPE = Digital Curation Centre and Digital Preservation Europe.
DSA/WDS = Data Seal of Approval/World Data System (DSA-WDS 2016).
Table 3
A qualitative illustration showing perceived effort needed to implement the criteria sets for USGS use. Both cost and complexity were included in the evaluation. The four criteria sets were deemed to have low implementation costs, requiring minimal resources.
| FMM | DCC | UFMS | DSA | ISO 16363 | FSPAC/NDSA | DSA/WDS |
|---|---|---|---|---|---|---|
| Medium | Low | Medium | Low | High | Low | Low |