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  1. 1. Network File SystemNetwork File System (NFS)(NFS) Submitted To:Submitted To: Rachana KamaliyaRachana Kamaliya PPresented Byresented By: Krupa Shingala: Krupa Shingala
  2. 2. Index What is File System? What is Network File System? Version of NFS NFS Architecture Advantages of NFS Disadvantages of NFS Conclusion References
  3. 3. What is File System? • A file system is a hierarchical structure (file tree) of files and directories. • This file tree uses directories to organize data and programs into groups, allowing the management of several directories and files at one time. • Some tasks are performed more efficiently on a file system than on each directory within the file system.
  4. 4. What is Network File System?What is Network File System? • NFS developed by SUN Microsystems for use on its UNIX-based workstations. • A distributed file system • Allows users to access files and directories located on remote computers • But, data potentially stored on another machine. • NFS builds on the Open Network Computing Remote Procedure Call (ONC RPC) system
  5. 5. Continue…Continue… Mechanism for storing files on a network. Allows users to ‘Share’ a directory. NFS most commonly used with UNIX systems. Other software platforms: -Mac OS, Microsoft Windows, Novell NetWare, etc. Major Goals: -simple crash recovery -reasonable performance :80% of a local drive
  6. 6. Versions and Variations Version 1 and Version 2 V1 Sun used only for in-house experimental purposes Did not release it to the public V2 of the protocol originally operated entirely over UDP and was meant to keep the protocol stateless, with locking (for example) implemented outside of the core protocol. Both suffered from performance problems Both suffered from security problems security dependant upon IP address
  7. 7. Version 3 NFS v3 can operate across TCP as well as UDP Support for asynchronous writes on the server Obtains multiple file name, handles and attributes Support for 64-bit file sizes and offsets Handle files larger than 4 gigabytes (GB) Improves performance, and allowed it to work more reliably across the Internet
  8. 8. Version 4 Currently version 2 and version 3 protocols are in use with version 4 under consideration for a standard includes more performance improvements Mandates strong security introduces a stateful protocol developed with the IETF (Internet Engineering Task Force)
  9. 9. File System File System NFS Client NFS Client Network NFS Server File System NFS Architecture
  10. 10. RPC request Action CREATE Creates (or truncates) a file in the directory LINK Creates a hard link LOOKUP Looks up a file in the directory MKDIR Makes a directory READADDR Reads the contents of a directory REMOVE Removes a file in the directory RENAME Renames a file in the directory RMDIR Removes a directory SYMLINK Creates a symbolic link NFS Protocol
  11. 11. RPC request Action GETATTR Get file attribute SETATTR Set file attribute LOOKUP File name search ACCESS Check access READ Read file WRITE Write to the file CREATE Create file REMOVE Remove file RENAME Rename file
  12. 12. stateless server and client server can be rebooted and user on client might be unaware of the reboot client/server distinction occurs at the application/user level not the system level highly flexible, so we need to be disciplined in our administration/configuration Advantages
  13. 13. Disadvantage uses RPC authentication easily spoofed filesystem data is transmitted in cleartext Data could be copied Network slower than local disk Complexity, Security issues.
  14. 14. Conclusion New technologies open up new possibilities for network file systems Cost of increased traffic over Ethernet may cause problems for xFS, cooperative caching.
  15. 15. References