A file system is a specific arrangement of files on any storage medium on which these files are stored. As everyone knows, various types of files can be found on computers, mobile phones and other mobile devices. The organization of such storage determines the format of the information contained, the method of its storage and naming. All these parameters are reflected in the file structure of operating systems. Each specific file system determines its specific ones:
- the size of the file or folder name;
- a set of system properties (attributes) for each type of file;
- 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:
- file naming;
- creates a unique interface for applications;
- determines the method of correlation and display of the logical model on a physical medium;
- provides system stability;
- It 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 multi-user file system provides the ability to restrict and completely exclude another user’s access to data stored on a computer, and also creates conditions for working together on files. The file structure of operating systems provides communication and interaction between the storage medium and the API for accessing files. Functionally, it looks something like this. At the moment when any application accesses the file, the program does not know exactly where, on which particular drive, how the required information is located. The only thing that the application knows for sure is only its own properties - the file size, its unique name and attributes. So it is precisely because each file structure of operating systems is unique in its characteristics that the place and method of placing a particular file on the medium (for example, on a hard medium) 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, into directories. Due to the specific structure, files and directories are recognized as free and used, faulty. At the same time, the file system is not directly connected to physical information storage devices ; there are so-called virtual systems, which are just a description of how to access files and directories.
Like most structures existing in nature, file has a hierarchical organization model. This assumes that all files on any OS are cataloged. The first operating system to use the hierarchical model for constructing such a structure was used in the Multics OS, and then in UNIX. Directories are combined into trees, which may 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:
- media oriented with random access (FAT32, HPFS, ext2);
- designed for media with sequential access;
- for network and virtual systems;
- for optical devices and flash memory.
Each of them has a file system limitation peculiar only to it, this ensures the uniqueness and security of the OS, and guarantees the inaccessibility of an outsider to information.