THE FILE SYSTEM

Objectives

• Provide long term, on-line, non-volatile storage (for programs, data, text etc)
• Allow information sharing (editors, compiler, utilities and databases such as airline reservation information)
• Convenient means of organising and accessing data (use of symbolic names, automatic back-up etc)

Achieved via a filing system, which :

• Manages disk space (usually as blocks)
• A mapping of symbolic names to physical address (like directories, for instance what does /homes/scmsomeone map to in terms of disk address)
• Protection :against system failure like power loss etc (backup, recovery - general archiving of data)
  : against unauthorised user access (allowing sharing between co-operating users, BUT protection from others)

Can consider the smallest unit of such a system to be a FILE : a named collection of data of arbitrary size on which various operations can be performed)