The partition type (or partition ID) in a partition's entry in the partition table inside a master boot record (MBR) is a byte value intended to specify the file system the partition contains or to flag special access methods used to access these partitions (e.g. special CHS mappings, LBA access, logical mapped geometries, special driver access, hidden partitions, secured or encrypted file systems, etc.).

Overview

Lists of assigned partition types to be used in the partition table in the MBR were originally maintained by IBM and

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internally. When the market of PC operating systems and disk tools grew and liberated, other vendors had a need to assign special partition types to their products as well. As Microsoft neither documented all partition types already assigned by them nor wanted to maintain foreign assignments, third parties started to simply assign partition types on their own behalf in a mostly uncoordinated trial-and-error manner. This led to various conflicting assignments sometimes causing severe compatibility problems between certain products. Several industry experts including Hale Landis, Ralf D. Brown, Matthias R. Paul, and Andries E. Brouwer in the 1990s started to research partition types and published (and later synchronized) partition type lists in order to help document the industry

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and thereby reduce the risk of further conflicts. Some of them also actively helped to maintain software dealing with partitions to work with the updated lists, indicated conflicts, devised additional detection methods and work-arounds for vendors, or engaged in coordinating new non-conflictive partition type assignments as well. It is up to an

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how to interpret the value. So the table specifies which

s or disk-related products introduced an ID and what file system or special partition type they mapped it to. Partitions with partition types unknown to the software should be treated as reserved but occupied disk storage space which should not be dealt with by the software, save for partition managers.

Local or Experimental Use

While the list is not officially maintained, ''new'' assignments should be coordinated. In particular temporary partition type assignments for local or experimental projects can utilize type 7Fh in order to avoid conflicts with already assigned types. This type was specially reserved for individual use as part of the ''Alternative OS Development Partition Standard'' (AODPS) initiative since 2002.

List of partition IDs

This is a list of known master boot record partition types on

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computers:

Notes

MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...

/ PC DOS 2.0-3.1 cannot cope with hard disk partitions outside the first 32 MB of the disk. Therefore,

FAT12 File Allocation Table (FAT) is a file system developed for personal computers. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. It is often supported for compatibility reasons by ...

and

FAT16 File Allocation Table (FAT) is a file system developed for personal computers. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. It is often supported for compatibility reasons by ...

volumes in primary partitions physically residing outside this area must not use partition IDs 01h and 04h, even if they were otherwise small enough to be recognized by these DOS versions. In order to hide these volumes from these DOS issues 06h can be used instead. DOS distinguishes FAT types by their number of clusters, not by their partition ID, therefore, this does not cause any problems for DOS 3.31 and higher except for a possibly wrong file system type display in

FDISK In computing, the fdisk command-line utility provides disk-partitioning functions, preparatory to defining file systems. fdisk features in the DOS, DR FlexOS, IBM OS/2, and Microsoft Windows operating systems, and in certain ports of FreeBS ...

. Used by

OS/2 OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 r ...

Boot Manager: 0Ah, 11h, 14h, 15h, 16h, 17h, 1Bh, 1Ch, 1Eh, 1Fh. Used by Free

FreeDOS FreeDOS (formerly Free-DOS and PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running legacy software and supporting embedded systems. FreeDOS can ...

: 8Dh, 90h, 91h, 92h, 97h, 98h, 9Ah, 9Bh. Known partition IDs for logical sectored FATs include: 08h (

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MS-DOS 3.x), 11h (

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MS-DOS 3.x), 14h (AST MS-DOS 3.x), 24h (NEC MS-DOS 3.30), 56h (

AT&T AT&T Inc. is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the world's largest telecommunications company by revenue and the third largest provider of mobile te ...

MS-DOS 3.x), E5h ( Tandy MS-DOS), F2h ( Sperry IT MS-DOS 3.x,

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MS-DOS 3.3 — also used by

Digital Research Digital Research, Inc. (DR or DRI) was a company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser DOS, DOS Plus, DR DOS and Gr ...

DOS Plus DOS Plus (erroneously also known as DOS+) was the first operating system developed by Digital Research's OEM Support Group in Newbury, Berkshire, UK, first released in 1985. DOS Plus 1.0 was based on CP/M-86 Plus combined with the PCMODE ...

2.1). While non-standard and sub-optimal these FAT variants are perfectly valid according to the specifications of the file system itself, although default issues of

/ PC DOS 3.x were not able to cope with them. Most of these vendor specific FAT12 and FAT16 variants can be mounted by more flexible file system implementations in operating systems such as DR-DOS simply by changing the partition ID to one of the recognized types. Also, if they no longer need to be recognized by their original operating systems, existing partitions can be "converted" into FAT12 and FAT16 volumes compliant with versions of MS-DOS/PC DOS like 5.0-6.3, which do not support logical sector sizes different from 512 bytes, by switching to a BPB with 32-bit entry for the number of sectors, as introduced since DOS 3.31, keeping the cluster size and reducing the logical sector size in the BPB down to 512 bytes, while at the same time increasing the counts of logical sectors per cluster, reserved logical sectors, total logical sectors, and logical sectors per FAT by the same factor. HP ''Volume Expansion'' is a variant of ''SpeedStor'' and uses partition IDs 21h, A1h, A3h, A4h, A6h, B1h, B3h, B4h, and B6h.

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uses partition IDs A8h, ABh, ACh, and AFh. Versions of

DR DOS DR-DOS (written as DR DOS, without a hyphen, in versions up to and including 6.0) is a disk operating system for IBM PC compatibles. Upon its introduction in 1988, it was the first DOS attempting to be compatible with IBM PC DOS and MS- ...

6.0 and higher use several of these partition IDs for secured FAT partitions with single-user security: C0h, C1h, C4h, C5h, C6h, CBh, CCh, CEh, CFh. Versions of Multiuser DOS use these partition IDs for secured FAT partitions with multi-user security: D0h, D1h, D4h, D5h, D6h. Versions of IMS

REAL/32 Multiuser DOS is a real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers. An evolution of the older Concurrent CP/M-86, Concurrent DOS and Concurrent DOS 386 operating systems, it was originally developed by ...

use partition IDs C0h and D0h for multi-user security.

QNX QNX ( or ) is a commercial Unix-like real-time operating system, aimed primarily at the embedded systems market. QNX was one of the first commercially successful microkernel operating systems. The product was originally developed in the early ...

partition IDs 07h, 08h, 09h, 4Dh (77), 4Eh (78), 4Fh (79), as well as B1h (177), B2h (178) and B3h (179).

Overview

Local or Experimental Use

List of partition IDs

See also

Notes

References

Further reading