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Hierarchical Storage Management

The digital content for the National Digital Library Program requires enormous quantities of digital storage to be accessible online. However, some of the master files are seldom accessed once they have been reviewed and derivative files generated. Hierarchical storage management (HSM) systems are designed to take advantage of the lower costs of storage media other than magnetic disk. HSM systems employ automatic migration of certain categories of files that have not been used recently to tape cartridges in a tape-library under robotic control. The layered file-system still appears to be a logical unit to users and allows the files to be retrieved when needed, although retrieval will take longer than for files held on the magnetic disk.

In 1996, LC introduced an HSM. By mid-1998 the price of disk storage had fallen sufficiently that LC stopped using this first hierarchical storage management system. However, this does not mean that LC will not explore the possibility again when the industry has developed software better able to handle the performance requirements for LC.

About -- Start -- Index -- Glossary

Hierarchical Storage Management

National Digital Library Program
Comments: caar@loc.gov (12/31/98)