Distributed Name Servers: Naming and Caching in Large Distributed Computing Environments

Abstract

Abstract : Name services facilitate sharing in distributed environments by allowing objects to be named unambiguously and maintaining a set of application- defined attributes for each named object. Existing distributed name services, which manage names based on their syntactic structure, may lack the flexibility needed by large, diverse, and evolving computing communities. A new approach, structure-free name management, separates three activities; choosing names, selecting the storage sites for object attributes, and resolving an object's name to its attributes. Administrative entities apportion the responsibility for managing various names, while the name service's information needed to locate an object's attributes can be independently reconfigured to improve performance or meet changing demands. An analytical performance model for distributed name services provides assessments of the effect of various design and configuration choices on the cost of name service operations. Measurements of Xerox's Grapevine registration service are used as inputs to the model to demonstrate the benefits of replicating an object's attributes to coincide with sizeable localities of interest. Additional performance benefits result from client's acquiring local caches of name service data treated as hints. A cache management strategy that maintains a minimum leval of cache accuracy is shown to be more effective than the usual technique of maximizing the hit ratio.