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Advanced Operating Systems

Advanced Operating Systems. File System Internals. UNIX File System Organisation. The Traditional UNIX organisation from Ed 7 onwards has been Boot Block, Super Block, Inodes, Data. UNIX File System Organisation. Searching and allocation is done through logical device and inumber.

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Advanced Operating Systems

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  1. Advanced Operating Systems File System Internals

  2. UNIX File System Organisation • The Traditional UNIX organisation from Ed 7 onwards has been • Boot Block, Super Block, Inodes, Data

  3. UNIX File System Organisation • Searching and allocation is done through logical device and inumber

  4. UNIX File System Organisation • Problems of Traditional UNIX FS • Fragmentation of disc • No way to use disc geometry • Short file names

  5. Berkeley Fast File System • Restructured File System organisation using cylinder groups • 1 or more cylinders per group • Identical superblocks in cylinder group • Superblocks offset for each in cylinder group

  6. Berkeley Fast File System • Inode/file allocation • File inode is allocated in parent directory cylinder group • New directory placed in new cylinder group • Large and small files are segregated • Use of 8k byte blocks & 1k fragements

  7. Berkeley Fast File System • Filename size changes • 255 character file names • Changed directory organisation • Quota system introduced • Symbolic links introduced • File truncation introduced

  8. Linux file system • Added VFS – Virtual File System • Allows other system to be added • Clean, object orientated, design of system • 3 parts • Inode object • File object • File system object

  9. Virtual File System

  10. Virtual File System • VFS Objects define an action for each file system • Each object has a pointer into a table of functions for each file system implementation • File system object is the hierarchy • Files found through fs-inode paring

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