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Chapter 20 Distributed File Systems
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Introduction
• Design Issues in Distributed File Systems • Transparency
• Semantics of File Sharing • Fault Tolerance
• DFS Performance • Case Studies
Operating Systems, by Dhananjay Dhamdherehamdhere 20.2 2
Copyright © 2008
Design Issues in Distributed File Systems
Operating Systems, by Dhananjay Dhamdherehamdhere 20.3 3
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Overview of DFS Operation • Remote file processing model
• File server agent and client agent are analogous to RPC’s stub processes
• For efficiency, the client agent and the cache manager are typically rolled into a single unit
Operating Systems, by Dhananjay Dhamdherehamdhere 20.4 4
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Transparency
• In a conventional file system, a user identifies a file through a path name
– User is aware that file belongs in a specific directory, but is not aware of its location in the system
• Location info field of the file’s directory entry indicates the file’s location on disk
• Location transparency can be provided in a DFS through a similar mechanism
– Location info: (node id, location)
• Location independence requires information in location info field to vary dynamically
Operating Systems, by Dhananjay Dhamdherehamdhere 20.5 5
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