Preserve involves the long-term, safe storage and backup of static, unchanging information. The logical architecture and functionality model is definded by the ISO Standard 14721 “OAIS”. Preservation is typically accomplished by the records management features of an ECM system and many are designed to help companies comply with government and industry regulations. Eventually, content ceases to change and becomes static. The preserve components of ECM handle the long-term, safe storage and backup of static information, as well as the temporary storage of information that does not need to be archived. Electronic archiving, a related concept, has substantially broader functionality than ECM Preserve components. Electronic archiving systems generally consist of a combination of administration software like records management, imaging or document management, library services or information retrieval systems, and storage subsystems. Other forms of media are also suitable for long-term archiving. If the desire is merely to ensure information is available in the future, microfilm is still viable; unlike many digital records, microfilm is readable without access to the specialized software that created it. Hybrid systems combine microfilm with electronic media and database-supported access. Long-term storage systems require the timely planning and regular performance of data migrations, in order to keep information available in the changing technical landscape. As storage technologies fall into disuse, information must be moved to newer forms of storage, so that the stored information remains accessible using contemporary systems. For example, data stored on floppy disks becomes essentially unusable if floppy disk drives are no longer readily available; migrating the data stored on floppy disks to Compact Discs preserves not only the data, but the ability to access it. This ongoing process is called continuous migration.
The Preserve components contain special viewers, conversion and migration tools, and long term storage media:
Long term storage media
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WORM optical disc: Write once read many (WORM) rotating digital optical storage media, including the 5.25-inch or 3.5-inch WORM disc in a protective sleeve, as well as CD-R and DVD-R. Recording methods vary for these media, which are held in jukeboxes for online and automated nearline access.
WORM tape: Magnetic tapes used in special drives, that can be as secure as optical write-once, read-many media if used properly with specially secured tapes.
WORM hard disk drive or hard disk sub-system: Magnetic disk storage with special software protection against overwriting, erasure, and editing; delivers security similar to optical write-once, read-many media. This category includes content-addressable storage.
Storage networks: Storage networks, such as network-attached storage (NAS) and storage area networks (SAN), can be used if they meet the requirements of edit-proof auditing with unchangeable storage and protection against manipulation and erasure.
Microform: Microforms like microfilm, microfiche, and aperture cards can be used to back up information that is no longer in use and does not require machine processing. It is typically used only to double-secure originally electronic information.
Paper: Paper still has use as a long-term storage medium, since it does not require migration, and can be read without any technical aids. In ECM systems, however, it is used only to double-secure originally electronic information. The ECM administers as well the location and other attributes of paper objects by records management functionality.
Long term preservation strategies
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To secure the long term availability of information different strategies are used for electronic archives.
Continuous migration of applications, index data, metadata and objects from older systems to new ones generates a lot of work, but secures the accessibility and usability of information. During this process, information that is no longer relevant can be deleted. Conversion technologies are used to update the format of the stored information, where needed.
Emulation of older software allows users to run and access the original data and objects. Special viewer software can identify the format of the preserved objects and can display the objects in the new software environment.
Standards for interfaces, metadata, data structures and object formats are important to secure the availability of information.