File systems. Characteristics of files.

File system - this is the important moment in the operating system, they are different, different in performance, reliability, different economical use of space.

All devices block access (which includes hard or floppy disks, CD-ROMs) for reading / writing data sectors operate. For hard or floppy disk sector size of 512 bytes, the CD-ROM sector size of 2048 bytes. Sector is the physical unit of information to the media.

The file system determines the format of the content and method of physically storing information, which is usually in the form of a group of files. The specific file system determines the size of the file (folder), the maximum possible size of the file and the partition set of file attributes. Some file systems provide service opportunities, for example, the distinction between access and encrypting files.

File system associates media on one side and an API to access files - the other. When an application accesses a file, it does not have a clue about how the information is located in a specific file, as well as on what type of physical media (CD, hard disk, magnetic tape, flash memory unit or the other), he recorded. Everyone knows that the program - is the file name, size, and attributes. This information it gets from the file system driver. This is a file system determines where and how the file will be written on a physical medium (such as a hard disk).

From the standpoint of operating system (OS), the entire disc is a set of clusters (typically 512 bytes or more) [1]. File system drivers are organizing clusters to files and directories (actually is a file containing a list of files in that directory). These drivers keep track of which of the clusters are being used, which are free, which are labeled as being faulty.

However, the file system is not necessarily directly related to the physical carrier of information. There are virtual file systems and network file systems, which are the only way to access the files on the remote computer.

Date: 2015-01-29; view: 991