FILE SYSTEMS

FILE SYSTEMS

1. FILE SYSTEM INTERFACE

   • user level more visible (Sisema portion of file):
     • access methods
     • Directory Structure
     • protection

2. FILE SYSTEM IMPLEMENTATION

   • less visible level operating system (the file system)
     • gesion allocation and free space
     • implementation directory

3. FILE SYSTEMS INTERFACE

   • The file is an entry in a directory.
   • The file can have attributes
     • Name
     • Identifier
     • Type
     • Location
     • Size
   • The file can be
     • free formed
     • indexed
     • structured
   • the operating system understands and interprets the file types.
   • can have different types of structure
     • Structure simple registration
       • lines
       • Fixed Size
       • Variable length
     • Complex Structures
       • Document format
       • File load relocatable

4. TYPE OF ACCESS

   • DIRECT ACCESS
     • Method useful for disks.
       • • The file is viewed as a numbered sequence of blocks or records.
       • • There are no restrictions on which blocks are read/written in any order.
       • • User now says "read n" rather than "read next".
   • SEQUENTIAL ACCESS
     • Se implementó al sistema de ficheros
       • • Data access a registration.
       • • This method is reasonable for the tape
   • OTHER ACCESS METHODS
     • Built on top of direct access and often implemented by a user utility.