Fdisk
Encyclopedia
On personal computer
operating system
s,
functions.
.
IBM
introduced
, and the IBM Personal Computer DOS version 2.0. Version 1 could be used to create one FAT12 DOS partition, delete it, change the active partition or display partition data. The master boot record supported up to four partitions, and the other three were intended for other operating systems such as CP/M-86
and Xenix
, which were expected to have their own partitioning utilities as
In August 1984, PC DOS 3.0 added FAT16 partitions, to support larger hard disks more efficiently.
In April 1987, PC DOS/
drives.
Most DOS
, are only capable of creating FAT
partitions of types FAT12 and FAT16.
A derivative of the MS-DOS
, and later Windows Me
. Only those
and later do not use
feature, as well as DiskPart
.
Unlike the
, but will also overwrite many sectors of data in the partition itself. (However, to create an extended partition any partition editor
must put extended boot records before each logical drive on the disk.) Users must be sure the correct disk/partition has been chosen before using a DOS/Windows
has many advanced features and is free software
.
needs at least one partition, namely for its root
file system
. It can use swap
files and/or swap partitions. Usually one will want a second Linux partition dedicated as a swap partition.
Other Intel based Unixes typically use a more elaborate arrangement. BSD-derived systems use a disklabel as their primary method of identifying distinct sections of the disk, usually termed slices. These slices may or may not correspond to partitions enumerated in the master boot record. A typical arrangement is for the entire Unix system to have a single partition allocated to it which is then subdivided into distinct slices for each filesystem and the swap area. Other partitions outside this dedicated one may be legitimately referenced in a disklabel - this is particularly true in dual boot
scenarios, where it is desired that the Unix system be able to access partitions used by other operating system
s residing on the same machine.
This approach is not mandatory since the MBR and bootlabel are two distinct records - it is technically possible (but not recommended) for the disklabel to describe a filesystem on an area of the disk that the MBR regards as unused. Regardless of the correlation between the two records, the 'entire disk' slice of the disklabel usually corresponds to the entire physical disk and not solely to the dedicated partition. In order to eliminate any possibility of confusion caused by these two (possibly contradictory) records, the sysadmin of these systems may elect to eliminate the master boot record from the disk. However, a disk laid out this way is unusable by any other operating systems.
The situation with System V-derived systems is similar to that with the BSDs, although the terminology usually used differs slightly. In this instance a single partition is subdivided using the divvy command, and such areas are often simply referred to as divisions.
On older Intel compatible hardware, the BIOS
that boots the system can often only access the first 1024 cylinders of the disk. For this reason a separate filesystem, often of only a few megabytes, is often created at the start of the disk to store the kernel image and a few auxiliary files needed at boot time, ensuring that they are readable by the BIOS. Once the kernel is loaded and has taken over responsibility for disk activity, the filesystem is typically mounted on /boot or /stand. There may also be reasons of security, ease of administration and backup, or testing, to use more than the minimum number of partitions.
shipped with two partition table managers up until version 4.0. These were the text mode
fdisk and the GUI
-based fdiskpm. The two have identical functionality, and can manipulate both FAT partitions and the more advanced HPFS partitions.
OS/2 versions 4.5 and higher (including eComStation
) can use the JFS filesystem as well as FAT and HPFS, and replace fdisk with the Logical Volume Manager
(LVM).
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s,
fdisk (for "fixed disk") is a commonly used name for a command-line utility that provides disk partitioningDisk partitioning
Disk partitioning is the act of dividing a hard disk drive into multiple logical storage units referred to as partitions, to treat one physical disk drive as if it were multiple disks. Partitions are also termed "slices" for operating systems based on BSD, Solaris or GNU Hurd...
functions.
fdisk writes the master boot recordMaster boot record
A master boot record is a type of boot sector popularized by the IBM Personal Computer. It consists of a sequence of 512 bytes located at the first sector of a data storage device such as a hard disk...
.
DOS and Windows
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
introduced
fdisk, Fixed Disk Setup Program version 1.00, with the March 1983 release of the IBM PC/XT, the first PC to store data on a hard diskHard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
, and the IBM Personal Computer DOS version 2.0. Version 1 could be used to create one FAT12 DOS partition, delete it, change the active partition or display partition data. The master boot record supported up to four partitions, and the other three were intended for other operating systems such as CP/M-86
CP/M-86
CP/M-86 was a version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. The commands are those of CP/M-80. Executable files used the relocatable .CMD file format...
and Xenix
Xenix
Xenix is a version of the Unix operating system, licensed to Microsoft from AT&T in the late 1970s. The Santa Cruz Operation later acquired exclusive rights to the software, and eventually superseded it with SCO UNIX ....
, which were expected to have their own partitioning utilities as
fdisk did not support them.In August 1984, PC DOS 3.0 added FAT16 partitions, to support larger hard disks more efficiently.
In April 1987, PC DOS/
fdisk 3.30 added support for extended partitions, which could hold up to 23 "logical" or volumeVolume (computing)
In the context of computer operating systems, volume is the term used to describe a single accessible storage area with a single file system, typically resident on a single partition of a hard disk. Similarly, it refers to the logical interface used by an operating system to access data stored on...
drives.
Most DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
fdisk programs, including the fdisk program that came with the original Windows 95Windows 95
Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft, and was a significant progression from the company's previous Windows products...
, are only capable of creating FAT
File Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
partitions of types FAT12 and FAT16.
A derivative of the MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
fdisk was provided with Windows 95, Windows 98Windows 98
Windows 98 is a graphical operating system by Microsoft. It is the second major release in the Windows 9x line of operating systems. It was released to manufacturing on 15 May 1998 and to retail on 25 June 1998. Windows 98 is the successor to Windows 95. Like its predecessor, it is a hybrid...
, and later Windows Me
Windows Me
Windows Millennium Edition, or Windows Me , is a graphical operating system released on September 14, 2000 by Microsoft, and was the last operating system released in the Windows 9x series. Support for Windows Me ended on July 11, 2006....
. Only those
fdisk versions shipping with Windows 95B or later are able to manipulate FAT32 partitions. Windows 2000Windows 2000
Windows 2000 is a line of operating systems produced by Microsoft for use on personal computers, business desktops, laptops, and servers. Windows 2000 was released to manufacturing on 15 December 1999 and launched to retail on 17 February 2000. It is the successor to Windows NT 4.0, and is the...
and later do not use
fdisk, they have the Logical Disk ManagerLogical Disk Manager
The Logical Disk Manager is an implementation of a logical volume manager for Microsoft Windows NT, developed by Microsoft and Veritas Software. It was introduced with the Windows 2000 operating system, and is supported in Windows XP, Windows Server 2003, Windows Vista and Windows 7...
feature, as well as DiskPart
Diskpart
In computing, diskpart is a command-line hard disk partitioning utility included in versions of the Windows NT operating system line from Windows 2000 onwards, replacing fdisk which was used in MS-DOS based operating systems....
.
Unlike the
fdisk programs for other operating systems, the fdisk programs for DOS and Windows 9x/Me not only alter data in the partition tablePartition table
The term partition table is most commonly associated with partition table but it may be used generically to refer to other "formats" that divide a disk drive into partitions, such as: GUID Partition Table, Apple partition map, or BSD disklabel.An alternative term to generically refer to partition...
, but will also overwrite many sectors of data in the partition itself. (However, to create an extended partition any partition editor
Partition editor
A partition editor is a kind of utility software designed to view, create, alter and delete disk partitions on a computer storage device, most commonly a hard disk, but often a USB flash drive or other storage medium.A partition is a section or segment of the storage space on a storage device...
must put extended boot records before each logical drive on the disk.) Users must be sure the correct disk/partition has been chosen before using a DOS/Windows
fdisk for partitioning. The fdisk /mbr switch is undocumented but well known for repairing the master boot record.FreeDOS
The implementation offdisk in FreeDOSFreeDOS
FreeDOS is an operating system for IBM PC compatible computers. FreeDOS is made up of many different, separate programs that act as "packages" to the overall FreeDOS Project...
has many advanced features and is free software
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
.
Unix-like systems
LinuxLinux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
needs at least one partition, namely for its root
Root directory
In computer file systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the root of a tree — the starting point where all branches originate.-Metaphor:...
file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
. It can use swap
Virtual memory
In computing, virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various forms of computer data storage , allowing a program to be designed as though there is only one kind of memory, "virtual" memory, which...
files and/or swap partitions. Usually one will want a second Linux partition dedicated as a swap partition.
Other Intel based Unixes typically use a more elaborate arrangement. BSD-derived systems use a disklabel as their primary method of identifying distinct sections of the disk, usually termed slices. These slices may or may not correspond to partitions enumerated in the master boot record. A typical arrangement is for the entire Unix system to have a single partition allocated to it which is then subdivided into distinct slices for each filesystem and the swap area. Other partitions outside this dedicated one may be legitimately referenced in a disklabel - this is particularly true in dual boot
Dual boot
Multi-boot or Multi-booting is the act of installing multiple operating systems on a computer, and being able to choose which one to boot when starting the computer. The term dual-booting refers to the common configuration of exactly two operating systems...
scenarios, where it is desired that the Unix system be able to access partitions used by other operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s residing on the same machine.
This approach is not mandatory since the MBR and bootlabel are two distinct records - it is technically possible (but not recommended) for the disklabel to describe a filesystem on an area of the disk that the MBR regards as unused. Regardless of the correlation between the two records, the 'entire disk' slice of the disklabel usually corresponds to the entire physical disk and not solely to the dedicated partition. In order to eliminate any possibility of confusion caused by these two (possibly contradictory) records, the sysadmin of these systems may elect to eliminate the master boot record from the disk. However, a disk laid out this way is unusable by any other operating systems.
The situation with System V-derived systems is similar to that with the BSDs, although the terminology usually used differs slightly. In this instance a single partition is subdivided using the divvy command, and such areas are often simply referred to as divisions.
On older Intel compatible hardware, the BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....
that boots the system can often only access the first 1024 cylinders of the disk. For this reason a separate filesystem, often of only a few megabytes, is often created at the start of the disk to store the kernel image and a few auxiliary files needed at boot time, ensuring that they are readable by the BIOS. Once the kernel is loaded and has taken over responsibility for disk activity, the filesystem is typically mounted on /boot or /stand. There may also be reasons of security, ease of administration and backup, or testing, to use more than the minimum number of partitions.
OS/2
OS/2OS/2
OS/2 is a computer operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for "Operating System/2," because it was introduced as part of the same generation change release as IBM's "Personal System/2 " line of second-generation personal...
shipped with two partition table managers up until version 4.0. These were the text mode
Text mode
Text mode is a kind of computer display mode in which the content of the screen is internally represented in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of character cells, each of which contains one of the characters of a...
fdisk and the GUI
Gui
Gui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...
-based fdiskpm. The two have identical functionality, and can manipulate both FAT partitions and the more advanced HPFS partitions.
OS/2 versions 4.5 and higher (including eComStation
EComStation
eComStation or eCS is a PC operating system based on OS/2, published by Serenity Systems. It includes several additions and accompanying software not present in the IBM version of the system.-Differences between eComStation and OS/2:...
) can use the JFS filesystem as well as FAT and HPFS, and replace fdisk with the Logical Volume Manager
Logical Volume Manager (Linux)
LVM is a logical volume manager for the Linux kernel; it manages disk drives and similar mass-storage devices, in particular large ones. The term "volume" refers to a disk drive or partition thereof...
(LVM).