~FILE SYSTEM MANAGEMENT~

~FILE SYSTEM MANAGEMENT~

File system management objectives

A file management system is that set of system software that provides

services to users and applications related to the use of files.

include storage of data and the ability to perform the operations listed

earlier.

Concept and design

The operating system abstract from the physical

properties of its storage devices to define a logical storage unit, the file. File are

mapped, by the operating system, on to physical devices. This storage device are

usually non volatile, so the contents are persistent thru power failures and

systems reboots.

File directory

The directory is itself a file, owned

by the operating system and accessible by various to users and applications,

information is generally provided indirectly by system routines. Thus, users
cannot directly access the directory even in read-only mode

File Sharing 

Access Rights

The file systems provide a flexible tool for the following extensive file sharing

among users. The file system should provide a number of options so that the

way in which a particular file is accessed can be controlled.

To meet the data-management needs and requirements of the user, whichTo guarantee, the extent possible that the data in the file are valid

This relieves the user or programmer of the necessity of developing

special purpose software for each application and provide the system with a

means of controlling its most important asset.[GROS86] suggests the following

objectives for file management system:

~ INPUT OUTPUT MANAGEMENT~

The delay between submission and job completion (call

turnaround time) may result from the amount of computing needed, or

from delays before the operating system start to process the job.

The introduction of disk technology has help in this regard. Rather

then the cards being read from the card reader directly into memory

and then the job being process, cards are read directly from the card

reader onto the disk. The location of card images is recorded in a table

kept by the operating system. When the job is executed, the operating

systems satisfy its requests for card reader input by reading from the

disk. Similarly, when the job request to output a line, that line is

copied into a system buffer and is written to the disk. When the job is

completed the output is actually printed. This form of processing is

called spooling.