The file structure of operating systems and their classification

A file system is a specific order of the location of files on any storage medium on which these files are stored. As you all know, different types of files can be on computers, mobile phones and other mobile devices. The organization of such storage determines the format of the information, the way it is stored and naming. All these parameters reflect the file structure of the operating systems. Each particular file system defines only its own:

- the size of the file or folder name;

- a set of system properties (attributes) for each file type;

- the maximum possible size of the file partition. For some systems, it is possible to perform some optional operations on files, the main such options are encryption and access control.

Any file structure of operating systems performs the following tasks:

- naming files;

- Creates a unique interface for applications;

- determines the way of correlation and mapping of the logical model on a physical medium;

- ensures the stability of the system;

- contains certain information that is necessary to ensure the interaction of the system with its other components (applications, services, kernel).

In addition, working with a file system of multi-user type provides the ability to restrict and even exclude the access of another user to the data stored on the computer, and also creates the conditions for working together on files. The file structure of operating systems provides communication and interaction between the media and the API for accessing files. Functionally it looks something like this. At a time when an application is accessing a file, the program does not know exactly where, on which disk, how the requested information is placed. The only thing that is known to an application is its own properties - the file size, its unique name and attributes. So precisely because each file structure of operating systems is unique in its characteristics, the place and method of placing a specific file on a medium (for example, on a hard disk) is established.

The hard drive itself is a collection of standard sized clusters, their size, as a rule, is 512 bytes. These clusters are organized into files, and those, in turn, are cataloged. Due to a certain structure, files and directories are recognized as free and used, defective. At the same time, the file system is not directly connected with physical storage devices , there are so-called virtual systems, which are only a description of the way to access files and directories.

Like most structures existing in nature, the file system has a hierarchical organization model. This implies that all the files on any OS are combined into directories. The first operating system, where a hierarchical model of such a structure was applied, was used in the Multics OS, and then in UNIX. Directories are combined into trees, which can be several, as is done in the OS in DOS / Windows.

The most common in modern devices are file systems, which, according to their functional purpose, can be classified into:

- oriented to media with random access (FAT32, HPFS, ext2);

- intended for carriers with sequential access;

- for network and virtual systems;

- for optical devices and flash memory.

Each of them has its own limitation of the file system, this ensures uniqueness and security of the OS, guaranteed unavailability of an unauthorized user to the information.