file Management System

File Management System

File Manager is also called the _____

Creating, deleting, modifying, controlling access to files

File Manager is also called the File Management System and is the software responsible for:

File Manager

Provides support for libraries of programs to online users, for spooling operation, and for interactive computing.

Files

are the building blocks of any operating system. Permanent storage of information & data.

Physical devices

OS maps files with?

File

Executable file

User prepare a program (file), ___ represent program and data. The output of program is called ______.

File access mechanism

refers to the manner in which the records of a file may be accessed.

Sequential File Access

Direct File Access

Indexed File Access

There are several ways to access files:

Sequential File Access

Is a method of accessing data sequentially/one record at a time by starting from the beginning of the file to its end

Sequential File Access

This access method is the most

primitive and straightforward method

of accessing files

Sequential File Access

simple, easy to implement and use.

Sequential File Access

slow and inefficient for random access operations or when working with large files

Direct File Access

Also known as Random file access.

Direct File Access

Allows users to access data directly

from any location within the file

without the need to read/write all the

records that come before it.

Direct File Access

speed and efficiency for

random access operations.

Direct File Access

more complex and

difficult to implement and use than

sequential file access.

Indexed File Access

Is a method that incorporates the benefits of

both sequential and direct file access.

Indexed File Access

Creating an index file that maps logical keys

or data elements to their corresponding

physical addresses within the file.

Indexed File Access

Index is searched sequentially and its pointer is used to access the file directly.

Indexed File Access

speed and efficiency for random

and sequential access operations.

Indexed File Access

requires additional storage

for the index, increase the cost and

complexity of the system

File Types

refers to the ability of the operating system to distinguish different types of file such as text files, source files, and binary files etc.

Ordinary Files

Directory Files

Special Files

Operating system like MS-DOS and UNIX have the following types of files:

Ordinary Files

These may have text, databases or executable program.

Ordinary Files

The user can apply various operations on such files like

- add, modify, delete or even remove the entire file.

Directorh Files

contains list of file and other related information to

those files.

Ordinary Files

These are the files that contains user information.

Directory Files

Also known as “folders” in other operating systems.

Directory Files

Folders that holds and organize multiple files.

Special Files

These files are also known as device files.

Special Files

Represents physical devices like

- disks, terminals, printers, networks, tape drive etc.

Character special Files

Block special Files

Special files have two types:

Character special files

data is handled character

by character as in case of terminals or printers.

Block special Files

data is handled in blocks as in

the case of disks and tapes.

Create, Read, Open, Close, Delete, Write, Append, Seek, Rename

9 File Operations

Directory

is a list of files that stores all the related information about the file it hold with the contents.

List of Files

Directory is a?

1. Single-level directory structure

2. Two-level directory structure

3. Tree-structured directory structure

Types of Directory

Single level directory structure

in a single level directory system, all the files are placed in one directory

Two level directory structure

the system maintains a master block that has one entry for each use

Tree level Directory Structure

in the tree-structured directory, the directory themselves are files. This files to the possibility of having sub-directories that can contain files and sub-subdirectories

Application Program Layer

Logical file system

File organization module

Basic file system

I/O control interface

Physical hardware device

6 layer of file system

Application program layer

user creates application program

Logical file system layer

manages the meta data information

File organization module layer

maintain information about file

Basic File System layer

Generate command for device driver also manage buffer memory and cache

I/O controll interface layer

it consists of device driver & interrupt

handler. Transfer data: between main memory to disk system.

Physical hardware device

contain actual hardware device

Data compression

A reduction in the amount of bits required to represent data is

known as

Data compression

can save storage capacity, speed up file

transfer and decrease costs for storage hardware and network

bandwidth.

Data compression

is performed by a program that uses a formula or

algorithm to determine how to shrink the size of the data.