chapter08 - Introduction File Service Architecture Sun...

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Unformatted text preview: Introduction File Service Architecture Sun Network File System The Andrew File System Recent advances Summary Chapter 7: Distributed File Systems File system persistent storage Distributed file system persistent storage information sharing similar (in some case better) performance and reliability Various kinds of storage systems Introduction Responsibilities Organization, storage, retrieval, naming, sharing and protection Important concepts related to file File Include data and attributes Directory A special file that provides a mapping from text names to internal file identifiers Metadata Extra management information; including attribute, directory etc File system architecture File system operations Applications access via library procedures Characteristics of file systems Transparency access transparency location transparency mobility transparency performance transparency scaling transparency Concurrent file updates concurrency control File replication better performance & fault tolerance Hardware and operating system heterogeneity Distributed file system requirements Fault tolerance idempotent operations: support at-least-semantics stateless server: restart from crash without recovery Consistency One-copy update semantics Security Authenticate, access control, secure channel Efficiency comparable with, or better than local file systems in performance and reliability Distributed file system requirements continuted SUN NFS First file service that was designed as a product [1984] Adopted as a internet standard Supported by almost platforms, e.g. Windows NT, Unix Andrew File System Campus information sharing system in CMU [1986] 800 workstations and 40 servers at CMU [1991] Case studies Introduction File Service Architecture Sun Network File System The Andrew File System Recent advances Summary Chapter 7: Distributed File Systems File service architecture Flat file service Operate on the contents of files Unique file identifier (UFID) Directory service Provide a mapping between text names to UFIDs Client module Support applications accessing remote file service transparently E.g. iterative request to directory service, cache files Three components of a file service Flat file service operations Comparison with Unix No open and close Read or write specifying a starting point Fault tolerance reasons for the differences Repeatable operations except for create, all operations are idempotent Stateless servers E.g. without pointer when operate on files restart after crash without recovery Flat file service interface Unix File System Users access rights are checked against the access mode requested in the open call Stateless DFS DFSs interface is opened to public...
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chapter08 - Introduction File Service Architecture Sun...

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