How Enterprise Content Management Systems Store and Preserve Content

The term "storage" means temporary storage while the term "preservation" means long-term storage. Both may use the same kinds of media to store the content, though long-term storage often uses read-only media.

In addition to repositories, the "storage" component includes library services and storage technologies. Library services provide access to the content in the repositories, and storage technologies determine the kind of media used.

What Are Repositories?

Repositories are simply places where data are stored. These could be scaled to different levels, as indicated below.

"File systems" are temporary in nature, and include caches for input and output.

"Content Management Systems" use databases or other specialized storage systems as the current "operating" repository.

"Databases" help administer the stored content, in addition to storing it. Querying and access-control facilities, for example, are provided by the databases.

"Data Warehouses" are complex systems based on databases, and store all kinds of content.

Library Services

Library services manage access to the data stored in online (allowing direct access to data) or offline (data are on a medium that has been removed from the system) storage media.

Library services also maintain an audit trail providing logs of content accesses and edits.

Storage Technologies

Magnetic hard drives organized as RAID, SAN, and NAS devices provide online access to content.

Magnetic tapes are used more for backing up and storing content offline, to provide for restoration in case online content is damaged or lost.

Compact discs, DVDs and other removable media are used both for storage and distribution of content.

Preservation of Content

Preservation involves safe storage of content for a longer term. In addition to storage media, this component can also involve conversion and migration tools, and special viewers.

WORM - Write Once Read Many - is a technology used with long-term storage media. There are WORM optical disks, tapes, and hard disks. These media are protected against overwriting, erasure, and editing either through hardware (CD-R) or special software.

In addition to electronic media, microfilm is still a viable option for such long-term storage of content that is not subject to further change. Microfilm and paper are still used for long-term storage of unchanging content, and paper has the advantage that it can be read without any special aids.

To be effective, the preservation component of Enterprise Content Management must be planned in advance, and migration of content to the long-term storage must be done regularly.

Standards must be decided upon for interfaces, metadata, data structures, and object formats to ensure safe migration and continued readability of the migrated content. Migration schedules must be developed and adhered to.

In the course of migrating current content to long-term media, content that is no more needed for any purpose can be deleted. Clear criteria and procedures must be in place to identify the content that can be deleted. Otherwise, needed content might also be deleted.

Conclusion

While "storage" means keeping content in current repositories, along with "library services" to access it conveniently, "preservation" involves migrating it to longer-term, possibly read-only, media.

Proper strategies must be developed and appropriate technologies must be used to ensure that storage and preservation are done easily and conveniently, and meet intended purposes.