© Oxford University Press 2011 DISTRIBUTED COMPUTING Sunita Mahajan Sunita Mahajan, Principal, Institute of Computer Science, MET League of Colleges, Mumbai Seema Shah Seema Shah, Principal, Vidyalankar Institute of Technology, Mumbai University
© Oxford University Press 2011 Chapter - 8 Distributed File System
© Oxford University Press 2011 Topics Introduction to DFS File models Distributed file system design Semantics of file sharing DFS implementation File caching in DFS Replication in DFS Case study
© Oxford University Press 2011 Introduction To DFS
© Oxford University Press 2011 Functions of DFS Permanent storage Remote information sharing User mobility Availability Diskless workstation
© Oxford University Press 2011 Components of DFS Storage service True file service Name service File service v/s file server
© Oxford University Press 2011 Desirable features of a good DFS Transparency User mobility Performance Simplicity Ease of use Scalability Availability Reliability Data integrity Security Support for heterogeneous systems
© Oxford University Press 2011 File Models
© Oxford University Press 2011 Classification of file models Based on file structure and how they can be modified
© Oxford University Press 2011 Distributed File System Design
© Oxford University Press 2011 Components of DFS True file service – Operations on individual files Directory service – Creating and managing directories
© Oxford University Press 2011 Types of File service interface
© Oxford University Press 2011 Remote access model NFS and Locus
© Oxford University Press 2011 Data caching model/Upload download model
© Oxford University Press 2011 Unit of data access transfer File level transfer Block level transfer Byte level transfer Record level transfer
© Oxford University Press 2011 Comparison
© Oxford University Press 2011 Directory server interface
© Oxford University Press 2011 Directory structure
© Oxford University Press 2011 Directory view
© Oxford University Press 2011 Naming Transparency Server 1Serve / Root Server 1Server 2Server 3Server 4 Dir 1 Dir 4 Y Dir 1 Dir 4 Y Fig 8.8 Naming Transparency
© Oxford University Press 2011 Directory naming approaches
© Oxford University Press 2011 Semantics Of File Sharing
© Oxford University Press 2011 File sharing
© Oxford University Press 2011 Types of file sharing semantics
© Oxford University Press 2011 Comparison
© Oxford University Press 2011 DFS Implementation
© Oxford University Press 2011 Methods of DFS lookup
© Oxford University Press 2011 Lookup methods
© Oxford University Press 2011 Stateful vs stateless servers
© Oxford University Press 2011 File Caching In DFS
© Oxford University Press 2011 File caching locations
© Oxford University Press 2011 Caching techniques-1
© Oxford University Press 2011 Caching techniques-2
© Oxford University Press 2011 Comparison of caching policies
© Oxford University Press 2011 Cache consistency
© Oxford University Press 2011 Comparison of Cache consistency algorithms
© Oxford University Press 2011 Replication In DFS
© Oxford University Press 2011 Replica creation
© Oxford University Press 2011 Update protocols Primary copy algorithm Voting algorithm
© Oxford University Press 2011 Case Study
© Oxford University Press 2011 Network File System architecture
© Oxford University Press 2011 NFS: caching
© Oxford University Press 2011 Google File system
© Oxford University Press 2011 Summary Introduction to DFS File models Distributed file system design Semantics of file sharing DFS implementation File caching in DFS Replication in DFS Case study