A distributed clustered architecture has multiple server mirrors that all access a complete and shared datastore. In addition, all database mirrors share a complete common data model and schema. Combinations of federated and clustered configurations also are possible and may have some advantages for knowledgebase design.
Credit or Source: Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science. science.energy.gov/ber/
U.S. DOE. 2009. U.S. Department of Energy Office of Science Systems Biology Knowledgebase for a New Era in Biology: A Genomics:GTL Report from the May 2008 Workshop, DOE/SC-113, U.S. Department of Energy Office of Science. (p. 45) (website)