Data management in a distributed file system for storage area networks

Many improvements in computer systems are initiated by new developments in the hardware on which these systems run. Currently, hardware for data storage are experiencing changes in connectivity, access semantics, and data rates because of storage area networks (SANs), which allow many computers to have shared access to storage devices over a high-speed network. The advent of SANs makes it possible to implement a high performance distributed file system by allowing client computers to obtain data directly from storage devices, rather than accessing data through a server that performs read and writes on their behalf.; However, a file system design that allows direct client access to data significantly changes both the performance and correctness of traditional protocols for data management. In this dissertation we define new protocols for concurrency control and synchronized access to files and data that exploit the SAN environment to improve performance. We also identify that the architecture of our direct access file system invalidates traditional protocols for providing operational guarantees when networks fail and authenticating the identity and actions of computers and their applications. We develop decentralized and distributed protocols for safe operation and authentication that are correct for the SAN environment. Our protocols make possible the implementation of a distributed file system that employs direct access to storage from clients to achieve high performance.