Storage devices

Types of HDD

Types of Mobile HDD

Partition Series

FAT

NTFS

Raid

Linux

Other Parts

Operating Systems

Windows

Other operating systems

Other

Appendix B. Operating System and Hard Disks

  • You know that hard disks are used to store information on them. You also know (see A.1 «Hard Disk Organization») that information is stored in sectors, and the sectors appear on discs in course of low-level formatting. Each sector contains the smallest possible 512-byte data block.

    All applications you are familiar with - office applications (text and graphical editors, spreadsheet processors) - and documents, tables, images, e-mail clients and Internet access software, and games are stored on hard disks as files. Files are grouped into folders to make working with them more convenient.

    Among various software the most important one is the operating system.

    An operating system provides all other applications running under its control with basic input/output access to all the resources of the PC, be that CPU, memory, or external devices (monitor, hard disks, floppy disks, CD-ROM, printer). All applications are loaded to memory from a hard disk and are executed under the control of the operating system.

    It would have been very inconvenient for a user to use data on disks if he had to deal only with addresses (numbers) of sectors comprising a file. That is why every file in the file system has its name. In DOS and Windows 3.x operating systems the name of the file contained 8 characters followed by a dot (.), which, in its turn, was followed by three more characters of the extension (or the type of the file). There could be fewer characters in the name and/or extension, and there were limitations as to what characters could be included in names and extensions.

    Windows NT and later versions of this OS allow files names that are up to 255 characters long. Full file name (including the disk letter and the name of the folder containing the file) can be up to 260 characters long (it is not recommended using file names longer than 50-70 characters).

    Other operating systems, for example, Linux, never had such strict limitations on file names as did DOS or Windows. The name of the file in Linux can be up to 256 characters long and have not one, but several extensions (or none at all). The path to the file in Linux can be up to 4096 characters long.

    To provide access to data organized in files and folders each operating system, for example, MS-DOS, Windows 95/98/Me/NT/2000/XP, Linux, has its own characteristic way to create and manage hard disk space, which is generally non-compatible with other OSes. However, it would be ineffective if one hard disk could be used by only one operating system. That is why a mechanism was created allowing several operating systems to use the hard disk. This mechanism is breaking the hard disk space into partitions.

    See also:
    Hard Disk Partitions
    Creating partitions for other OSes
    ID_AOS_PRIMARY_AND_LOGICAL
    Formatting Hard Disks
    File Systems
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