File management (Fig.12.2)
Users and application programs interact with file system by means of commands for performing operations on files.
These commands are translated into specific file manipulation commands, after ensuring that the kind of access requested is allowed.
User view may be that of records or few bytes, but the actual IO is done in blocks. Data conversion to block “packing” is done. Optimized where applicable.
Now IO subsystems takes over by translating the file sub commands into IO subsystem (disk IO) commands.