Editing Disk partitioning (section)

== PC partition types ==

=== MBR ===
{{See also|Partition type}}
This section describes the [[master boot record]] (MBR) partitioning scheme, as used historically in [[DOS]], [[Microsoft Windows]] and [[Linux]] (among others) on [[PC-compatible]] computer systems. As of the mid-2010s, most new computers use the [[GUID Partition Table]] (GPT) partitioning scheme instead.{{cn|date=January 2025}} For examples of other partitioning schemes, see the general article on [[Disk partitioning#Partition table|partition tables]].

The total data storage space of a PC HDD on which MBR partitioning is implemented can contain at most four ''primary partitions'', or alternatively three primary partitions and an ''[[#Extended partition|extended partition]]''. The ''Partition Table'', located in the master boot record, contains 16-byte entries, each of which describes a partition.

The ''partition type'' is identified by a 1-byte code found in its partition table entry. Some of these codes (such as {{mono|[[Partition type#PID 05h|0x05]]}} and {{mono|[[Partition type#PID 0Fh|0x0F]]}}) may be used to indicate the presence of an [[extended boot record|extended partition]]. Most are used by an operating system's bootloader (that examines partition tables) to decide if a partition contains a file system that can be ''mounted / accessed'' for reading or writing data.

=== Primary partition ===
{{Further|Partition type}}
A primary  partition contains one file system. In [[DOS]] and all early versions of [[Microsoft Windows]] systems, [[Microsoft]] required what it called the [[system partition]] to be the first partition. All Windows operating systems from Windows 95 onwards can be located on (almost) any partition, but the boot files (<code>io.sys</code>, <code>bootmgr</code>, <code>ntldr</code>, etc.) must reside on a primary partition.  However, other factors, such as a PC's [[BIOS]] (see [[Booting#Boot sequence|Boot sequence on standard PC]]) may also impose specific requirements as to which partition must contain the primary OS.

The partition type ''code'' for a primary partition can either correspond to a file system contained within (e.g., {{mono|[[Partition type#PID 07h|0x07]]}} means either an [[NTFS]] or an OS/2 [[High Performance File System|HPFS]] file system) or indicate that the partition has a special use (e.g., code {{mono|[[Partition type#PID 82h|0x82]]}} usually indicates a Linux ''swap'' partition). The [[FAT16]] and [[FAT32]] file systems have made use of a number of partition type codes due to the limits of various DOS and Windows OS versions. Though a Linux operating system may recognize a number of different file systems ([[ext4]], [[ext3]], [[ext2]], [[ReiserFS]], etc.), they have all consistently used the same partition type code: {{mono|[[Partition type#PID 83h|0x83]]}} ([[file system#Linux|Linux native file system]]).

=== Extended partition ===
{{further|Extended boot record}}
An HDD may contain only one extended partition, but that extended partition can be subdivided into multiple logical partitions. DOS/Windows systems may then [[Drive letter assignment|assign a unique drive letter]] to each logical partition. [[GUID partition table]] (GPT) only has the primary partition, doesn't have the extended partition and the logical partition.

=== Boot partitions ===
{{See also|System partition and boot partition}}

==== BIOS boot partition ====
BIOS boot partition (BIOS BP) is a share of the storage device used to keep software that boots the operating system, a [[bootloader]]. It may be an operating system kernel image or bootloader or a completely separate piece of software.<ref name=":1">{{Cite web|title=What are system partition and boot partition?|url=https://www.easyuefi.com/wintousb/faq/en-US/What-are-system-partitions-and-boot-partitions.html|url-status=live|access-date=2021-12-07|website=www.easyuefi.com|archive-url=https://web.archive.org/web/20180716142214/https://www.easyuefi.com/wintousb/faq/en-US/What-are-system-partitions-and-boot-partitions.html |archive-date=2018-07-16 }}</ref><ref name=":0">{{Cite book|last=Cross|first=Michael|url=https://www.worldcat.org/oclc/272383168|title=Scene of the cybercrime.|date=2008|publisher=Syngress Pub|others=Debra Littlejohn Shinder|isbn=978-0-08-048699-4|edition=2nd|location=Burlington, MA|oclc=272383168}}</ref>{{Rp|page=136}}

==== EFI system partition ====
[[EFI system partition]] is the same as BIOS BP, but is loaded by EFI firmware instead of BIOS.<ref name=":1" /><ref name=":0" />{{Rp|page=136}}