The GUID Partition Table (GPT) is a standard for the layout of partition tables of a physical computer storage device, such as a hard disk drive or solid-state drive, using universally unique identifiers (UUIDs), which are also known as globally unique identifiers (GUIDs). Forming a part of the Unified Extensible Firmware Interface (UEFI) standard (Unified EFI Forum-proposed replacement for the PC BIOS), it is nevertheless also used for some BIOSs, because of the limitations of master boot record (MBR) partition tables, which use 32 bits for logical block addressing (LBA) of traditional 512-byte disk sectors.
All modern personal computer operating systems support GPT. Some, including macOS and Microsoft Windows on the x86 architecture, support booting from GPT partitions only on systems with EFI firmware, but FreeBSD and most Linux distributions can boot from GPT partitions on systems with either the BIOS or the EFI firmware interface.
The Master Boot Record (MBR) partitioning scheme, widely used since the early 1980s, imposed limitations for use of modern hardware. The available size for block addresses and related information is limited to 32 bits. For hard disks with 512‑byte sectors, the MBR partition table entries allow a maximum size of 2 TiB (2³² × 512‑bytes) or 2.20 TB (2.20 × 10¹² bytes). [1]
In the late 1990s, Intel developed a new partition table format as part of what eventually became the Unified Extensible Firmware Interface (UEFI). The GUID Partition Table is specified in chapter 5 of the UEFI 2.8 specification. [2] GPT uses 64 bits for logical block addresses, allowing a maximum disk size of 264 sectors. For disks with 512‑byte sectors, the maximum size is 8 ZiB (264 × 512‑bytes) or 9.44 ZB (9.44 × 10²¹ bytes). [1] For disks with 4,096‑byte sectors the maximum size is 64 ZiB (264 × 4,096‑bytes) or 75.6 ZB (75.6 × 10²¹ bytes).
In 2010, hard-disk manufacturers introduced drives with 4,096‑byte sectors (Advanced Format). [3] For compatibility with legacy hardware and software, those drives include an emulation technology (512e) that presents 512‑byte sectors to the entity accessing the hard drive, despite their underlying 4,096‑byte physical sectors. [4] Performance could be degraded on write operations, when the drive is forced to perform two read-modify-write operations to satisfy a single misaligned 4,096‑byte write operation. [4] Since April 2014, enterprise-class drives without emulation technology (4K native) have been available on the market. [5] [6]
Readiness of the support for 4 KB logical sectors within operating systems differs among their types, vendors and versions. [7] For example, Microsoft Windows supports 4K native drives since Windows 8 and Windows Server 2012 (both released in 2012) in UEFI. [8]
Like MBR, GPT uses logical block addressing (LBA) in place of the historical cylinder-head-sector (CHS) addressing. The protective MBR is stored at LBA 0, and the GPT header is in LBA 1, with a backup GPT header stored at the final LBA. The GPT header has a pointer to the partition table (Partition Entry Array), which is typically at LBA 2. Each entry on the partition table has a size of 128 bytes. The UEFI specification stipulates that a minimum of 16,384 bytes, regardless of sector size, are allocated for the Partition Entry Array. [9] Thus, on a disk with 512-byte sectors, at least 32 sectors are used for the Partition Entry Array, and the first usable block is at LBA 34 or higher, while on a 4,096-byte sectors disk, at least 4 sectors are used for the Partition Entry Array, and the first usable block is at LBA 6 or higher.
For limited backward compatibility, the space of the legacy Master Boot Record (MBR) is still reserved in the GPT specification, but it is now used in a way that prevents MBR-based disk utilities from misrecognizing and possibly overwriting GPT disks. This is referred to as a protective MBR. [10]
A single partition of type EEh , encompassing the entire GPT drive (where "entire" actually means as much of the drive as can be represented in an MBR), is indicated and identifies it as GPT. Operating systems and tools which cannot read GPT disks will generally recognize the disk as containing one partition of unknown type and no empty space, and will typically refuse to modify the disk unless the user explicitly requests and confirms the deletion of this partition. This minimizes accidental erasures. [10] Furthermore, GPT-aware OSes may check the protective MBR and if the enclosed partition type is not of type EEh or if there are multiple partitions defined on the target device, the OS may refuse to manipulate the partition table. [11]
If the actual size of the disk exceeds the maximum partition size representable using the legacy 32-bit LBA entries in the MBR partition table, the recorded size of this partition is clipped at the maximum, thereby ignoring the rest of the disk. This amounts to a maximum reported size of 2 TiB, assuming a disk with 512 bytes per sector (see 512e). It would result in 16 TiB with 4 KiB sectors (4Kn), but since many older operating systems and tools are hard coded for a sector size of 512 bytes or are limited to 32-bit calculations, exceeding the 2 TiB limit could cause compatibility problems. [10]
In operating systems that support GPT-based boot through BIOS services rather than EFI, the first sector may also still be used to store the first stage of the bootloader code, but modified to recognize GPT partitions. The bootloader in the MBR must not assume a sector size of 512 bytes. [10]
Offset | Length | Contents |
---|---|---|
0 (0x00) | 8 bytes | Signature ("EFI PART", 45h 46h 49h 20h 50h 41h 52h 54h or 0x5452415020494645ULL [a] on little-endian machines) |
8 (0x08) | 4 bytes | Revision number of header - 1.0 (00h 00h 01h 00h) for UEFI 2.10 |
12 (0x0C) | 4 bytes | Header size in little endian (in bytes, usually 5Ch 00h 00h 00h or 92 bytes) |
16 (0x10) | 4 bytes | CRC32 of header (offset +0 to +0x5c) in little endian, with this field zeroed during calculation |
20 (0x14) | 4 bytes | Reserved; must be zero |
24 (0x18) | 8 bytes | Current LBA (location of this header copy) |
32 (0x20) | 8 bytes | Backup LBA (location of the other header copy) |
40 (0x28) | 8 bytes | First usable LBA for partitions (primary partition table last LBA + 1) |
48 (0x30) | 8 bytes | Last usable LBA (secondary partition table first LBA − 1) |
56 (0x38) | 16 bytes | Disk GUID in mixed endian [11] |
72 (0x48) | 8 bytes | Starting LBA of array of partition entries (usually 2 for compatibility) |
80 (0x50) | 4 bytes | Number of partition entries in array |
84 (0x54) | 4 bytes | Size of a single partition entry (usually 80h or 128) |
88 (0x58) | 4 bytes | CRC32 of partition entries array in little endian |
92 (0x5C) | * | Reserved; must be zeroes for the rest of the block (420 bytes for a sector size of 512 bytes; but can be more with larger sector sizes) |
The partition table header defines the usable blocks on the disk. It also defines the number and size of the partition entries that make up the partition table (offsets 80 and 84 in the table). [2] : 119
Offset | Length | Contents |
---|---|---|
0 (0x00) | 16 bytes | Partition type GUID (mixed endian [11] ) |
16 (0x10) | 16 bytes | Unique partition GUID (mixed endian) |
32 (0x20) | 8 bytes | First LBA (little endian) |
40 (0x28) | 8 bytes | Last LBA (inclusive, usually odd) |
48 (0x30) | 8 bytes | Attribute flags (e.g. bit 60 denotes read-only) |
56 (0x38) | 72 bytes | Partition name (36 UTF-16LE code units) |
After the primary header and before the backup header, the Partition Entry Array describes partitions, using a minimum size of 128 bytes for each entry block. [12] The starting location of the array on disk, and the size of each entry, are given in the GPT header. The first 16 bytes of each entry designate the partition type's globally unique identifier (GUID). For example, the GUID for an EFI system partition is C12A7328-F81F-11D2-BA4B-00A0C93EC93B. The second 16 bytes are a GUID unique to the partition. Then follow the starting and ending 64 bit LBAs, partition attributes, and the 36 character (max.) Unicode partition name. As is the nature and purpose of GUIDs and as per RFC 4122, no central registry is needed to ensure the uniqueness of the GUID partition type designators. [13] [2] : 2200
The 64-bit partition table attributes are shared between 48-bit common attributes for all partition types, and 16-bit type-specific attributes:
Bit | Content |
---|---|
0 | Platform required (required by the computer to function properly, OEM partition for example, disk partitioning utilities must preserve the partition as is) |
1 | EFI firmware should ignore the content of the partition and not try to read from it |
2 | Legacy BIOS bootable (equivalent to active flag (typically bit 7 set) at offset +0h in partition entries of the MBR partition table) [14] |
3–47 | Reserved for future use |
48–63 | Defined and used by the individual partition type |
Microsoft defines the type-specific attributes for basic data partition as: [15] [16]
Bit | Content |
---|---|
60 | Read-only |
61 | Shadow copy (of another partition) |
62 | Hidden |
63 | No drive letter (i.e. do not automount) |
Google defines the type-specific attributes for ChromeOS kernel as: [17]
Bit | Content |
---|---|
56 | Successful boot flag |
55–52 | Tries remaining |
51–48 | Priority (15: highest, 1: lowest, 0: not bootable) |
OS family | Version or edition | Platform | Read and write support | Boot support | Note |
---|---|---|---|---|---|
FreeBSD | Since 7.0 | IA-32, x86-64, ARM | Yes | Yes | In a hybrid configuration, both GPT and MBR partition identifiers may be used. |
Linux | Most of the x86 Linux distributions Fedora 8+ and Ubuntu 8.04+ [18] | IA-32, x86-64, ARM | Yes | Yes | Tools such as gdisk, GNU Parted, [19] [20] util-linux v2.23+ fdisk, [21] [22] SYSLINUX, GRUB 0.96 + patches and GRUB 2 have been GPT-enabled. Limited to 256 partitions per disk. [23] |
macOS | Since 10.4.0 (some features since 10.4.6) [24] | IA-32, x86-64, PowerPC, Apple silicon | Yes | Yes | Only Intel and Apple silicon Mac computers can boot from GPT. Apple silicon macOS are utilise GPT as partition format, but Apple silicon Mac computers are not utilise EFI as boot firmware. [25] |
MidnightBSD | Since 0.4-CURRENT | IA-32, x86-64 | Yes | Requires CSM | In a hybrid configuration, both GPT and MBR partition identifiers may be used. |
NetBSD | Since 6.0 [26] | IA-32, [27] x86-64, [28] ARM | Yes | Yes | |
OpenBSD | Since 5.9 | IA-32, x86-64, ARM | Yes | Yes | [29] |
Solaris | Since Solaris 10 | IA-32, x86-64, SPARC | Yes | Yes | [30] |
HP-UX | Since HP-UX 11.20 | IA-64 | Yes | Yes | [31] |
Windows 7 and earlier do not support UEFI on 32-bit platforms, and therefore do not allow booting from GPT partitions. [32]
OS version | Release date | Platform | Read or write support | Boot support | Note |
---|---|---|---|---|---|
Windows 9x | 1995-08-24 | IA-32 | No [b] | No | |
Windows XP | 2001-10-25 | IA-32 | No | No | |
Windows Server 2003 | 2003-04-24 | IA-32 | No | No | |
Windows Server 2003 SP1 | 2005-03-30 | IA-32 | Yes | No | MBR takes precedence in hybrid configuration. |
Windows Vista | 2006-07-22 | IA-32 | Yes | No | MBR takes precedence in hybrid configuration. |
Windows Server 2008 | 2008-02-27 | IA-32 | Yes | No | MBR takes precedence in hybrid configuration. |
Windows 7 | 2009-10-22 | IA-32 | Yes | No | MBR takes precedence in hybrid configuration. |
Windows 8 | 2012-08-01 | IA-32 | Yes | Requires UEFI [33] | MBR takes precedence in hybrid configuration. |
Windows 8.1 | 2013-08-27 | IA-32 | Yes | Requires UEFI [34] | MBR takes precedence in hybrid configuration. |
Windows 10 | 2015-07-29 | IA-32 | Yes | Requires UEFI [35] | MBR takes precedence in hybrid configuration. |
Limited to 128 partitions per disk. [32]
OS version | Release date | Platform | Read and write support | Boot support | Note |
---|---|---|---|---|---|
Windows XP 64-Bit Edition for Itanium systems, Version 2002 | 2001-10-25 | IA-64 | Yes | Yes | MBR takes precedence in hybrid configuration. |
Windows XP 64-Bit Edition, Version 2003 | 2003-03-28 | IA-64 | Yes | Yes | MBR takes precedence in hybrid configuration. |
Windows XP Professional x64 Edition Windows Server 2003 | 2005-04-25 [36] | x64 | Yes | No [c] | MBR takes precedence in hybrid configuration. |
Windows Server 2003 | 2005-04-25 | IA-64 | Yes | Yes | MBR takes precedence in hybrid configuration. |
Windows Vista | 2006-07-22 | x64 | Yes | Requires UEFI [d] | MBR takes precedence in hybrid configuration. |
Windows Server 2008 | 2008-02-27 | x64 | Yes | Requires UEFI | MBR takes precedence in hybrid configuration. |
Windows Server 2008 | 2008-02-27 | IA-64 | Yes | Yes | MBR takes precedence in hybrid configuration. |
Windows 7 | 2009-10-22 | x64 | Yes | Requires UEFI [e] | MBR takes precedence in hybrid configuration. |
Windows Server 2008 R2 | 2009-10-22 | IA-64 | Yes | Yes | MBR takes precedence in hybrid configuration. |
Windows 8 Windows Server 2012 | 2012-08-01 | x64 | Yes | Requires UEFI [38] | MBR takes precedence in hybrid configuration. |
Windows 8.1 | 2013-08-27 | x64 | Yes | Requires UEFI [39] | MBR takes precedence in hybrid configuration. |
Windows 10 | 2015-07-29 | x64 | Yes | Requires UEFI [40] | MBR takes precedence in hybrid configuration. |
Windows Server 2016 | 2016-10-12 | x64 | Yes | Requires UEFI | MBR takes precedence in hybrid configuration. |
Windows Server 2019 | 2018-10-02 | x64 | Yes | Requires UEFI | MBR takes precedence in hybrid configuration. |
Windows Server 2022 | 2021-08-18 [41] | x64 | Yes | Requires UEFI | MBR takes precedence in hybrid configuration. |
Windows 11 | 2021-10-05 | x64, ARM64 | Yes | Yes | UEFI is a system requirement for Windows 11. |
The accessibility of this table is in question. The specific issue is: screen readers can not read content that is collapsed and hidden . Relevant discussion may be found on the talk page. (September 2024) |
"Partition type GUID" means that each partition type is strictly identified by a GUID number unique to that type, and therefore partitions of the same type will all have the same "partition type GUID". Each partition also has a "partition unique GUID" as a separate entry, which as the name implies is a unique id for each partition.
Operating system | Partition type | Globally unique identifier (GUID) [f] | |
---|---|---|---|
OS independent | Unused entry | 00000000-0000-0000-0000-000000000000 | |
MBR partition scheme | 024DEE41-33E7-11D3-9D69-0008C781F39F | ||
EFI System partition | C12A7328-F81F-11D2-BA4B-00A0C93EC93B | ||
BIOS boot partition [g] | 21686148-6449-6E6F-744E-656564454649 | ||
Intel Fast Flash (iFFS) partition (for Intel Rapid Start technology) [42] [43] | D3BFE2DE-3DAF-11DF-BA40-E3A556D89593 | ||
Sony boot partition [h] | F4019732-066E-4E12-8273-346C5641494F | ||
Lenovo boot partition [h] | BFBFAFE7-A34F-448A-9A5B-6213EB736C22 | ||
Windows | Microsoft Reserved Partition (MSR) [45] | E3C9E316-0B5C-4DB8-817D-F92DF00215AE | |
Basic data partition [45] [i] | EBD0A0A2-B9E5-4433-87C0-68B6B72699C7 | ||
Logical Disk Manager (LDM) metadata partition [45] | 5808C8AA-7E8F-42E0-85D2-E1E90434CFB3 | ||
Logical Disk Manager data partition [45] | AF9B60A0-1431-4F62-BC68-3311714A69AD | ||
Windows Recovery Environment [45] | DE94BBA4-06D1-4D40-A16A-BFD50179D6AC | ||
IBM General Parallel File System (GPFS) partition | 37AFFC90-EF7D-4E96-91C3-2D7AE055B174 | ||
Storage Spaces partition [47] | E75CAF8F-F680-4CEE-AFA3-B001E56EFC2D | ||
Storage Replica partition [48] | 558D43C5-A1AC-43C0-AAC8-D1472B2923D1 | ||
HP-UX | Data partition | 75894C1E-3AEB-11D3-B7C1-7B03A0000000 | |
Service partition | E2A1E728-32E3-11D6-A682-7B03A0000000 | ||
Linux [49] [50] [51] [52] | Linux filesystem data [i] | 0FC63DAF-8483-4772-8E79-3D69D8477DE4 | |
RAID partition | A19D880F-05FC-4D3B-A006-743F0F84911E | ||
Root partition | Alpha [49] | 6523F8AE-3EB1-4E2A-A05A-18B695AE656F | |
ARC [49] | D27F46ED-2919-4CB8-BD25-9531F3C16534 | ||
ARM 32‐bit [49] | 69DAD710-2CE4-4E3C-B16C-21A1D49ABED3 | ||
AArch64 [49] | B921B045-1DF0-41C3-AF44-4C6F280D3FAE | ||
IA-64 [49] | 993D8D3D-F80E-4225-855A-9DAF8ED7EA97 | ||
LoongArch 64‐bit [49] | 77055800-792C-4F94-B39A-98C91B762BB6 | ||
mips: 32‐bit MIPS big‐endian [49] | E9434544-6E2C-47CC-BAE2-12D6DEAFB44C | ||
mips64: 64‐bit MIPS big‐endian [49] | D113AF76-80EF-41B4-BDB6-0CFF4D3D4A25 | ||
mipsel: 32‐bit MIPS little‐endian [49] | 37C58C8A-D913-4156-A25F-48B1B64E07F0 | ||
mips64el: 64‐bit MIPS little‐endian [49] | 700BDA43-7A34-4507-B179-EEB93D7A7CA3 | ||
PA-RISC [49] | 1AACDB3B-5444-4138-BD9E-E5C2239B2346 | ||
32‐bit PowerPC [49] | 1DE3F1EF-FA98-47B5-8DCD-4A860A654D78 | ||
64‐bit PowerPC big‐endian [49] | 912ADE1D-A839-4913-8964-A10EEE08FBD2 | ||
64‐bit PowerPC little‐endian [49] | C31C45E6-3F39-412E-80FB-4809C4980599 | ||
RISC-V 32‐bit [49] | 60D5A7FE-8E7D-435C-B714-3DD8162144E1 | ||
RISC-V 64‐bit [49] | 72EC70A6-CF74-40E6-BD49-4BDA08E8F224 | ||
s390 [49] | 08A7ACEA-624C-4A20-91E8-6E0FA67D23F9 | ||
s390x [49] | 5EEAD9A9-FE09-4A1E-A1D7-520D00531306 | ||
TILE-Gx [49] | C50CDD70-3862-4CC3-90E1-809A8C93EE2C | ||
x86 [49] | 44479540-F297-41B2-9AF7-D131D5F0458A | ||
x86-64 [49] | 4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709 | ||
/usr partition | Alpha [49] | E18CF08C-33EC-4C0D-8246-C6C6FB3DA024 | |
ARC [49] | 7978A683-6316-4922-BBEE-38BFF5A2FECC | ||
ARM 32‐bit [49] | 7D0359A3-02B3-4F0A-865C-654403E70625 | ||
AArch64 [49] | B0E01050-EE5F-4390-949A-9101B17104E9 | ||
IA-64 [49] | 4301D2A6-4E3B-4B2A-BB94-9E0B2C4225EA | ||
LoongArch 64‐bit [49] | E611C702-575C-4CBE-9A46-434FA0BF7E3F | ||
mips: 32‐bit MIPS big‐endian [49] | 773B2ABC-2A99-4398-8BF5-03BAAC40D02B | ||
mips64: 64‐bit MIPS big‐endian [49] | 57E13958-7331-4365-8E6E-35EEEE17C61B | ||
mipsel: 32‐bit MIPS little‐endian [49] | 0F4868E9-9952-4706-979F-3ED3A473E947 | ||
mips64el: 64‐bit MIPS little‐endian [49] | C97C1F32-BA06-40B4-9F22-236061B08AA8 | ||
PA-RISC [49] | DC4A4480-6917-4262-A4EC-DB9384949F25 | ||
32‐bit PowerPC [49] | 7D14FEC5-CC71-415D-9D6C-06BF0B3C3EAF | ||
64‐bit PowerPC big‐endian [49] | 2C9739E2-F068-46B3-9FD0-01C5A9AFBCCA | ||
64‐bit PowerPC little‐endian [49] | 15BB03AF-77E7-4D4A-B12B-C0D084F7491C | ||
RISC-V 32‐bit [49] | B933FB22-5C3F-4F91-AF90-E2BB0FA50702 | ||
RISC-V 64‐bit [49] | BEAEC34B-8442-439B-A40B-984381ED097D | ||
s390 [49] | CD0F869B-D0FB-4CA0-B141-9EA87CC78D66 | ||
s390x [49] | 8A4F5770-50AA-4ED3-874A-99B710DB6FEA | ||
TILE-Gx [49] | 55497029-C7C1-44CC-AA39-815ED1558630 | ||
x86 [49] | 75250D76-8CC6-458E-BD66-BD47CC81A812 | ||
x86-64 [49] | 8484680C-9521-48C6-9C11-B0720656F69E | ||
Root verity partition for dm-verity | Alpha [49] | FC56D9E9-E6E5-4C06-BE32-E74407CE09A5 | |
ARC [49] | 24B2D975-0F97-4521-AFA1-CD531E421B8D | ||
ARM 32‐bit [49] | 7386CDF2-203C-47A9-A498-F2ECCE45A2D6 | ||
AArch64 [49] | DF3300CE-D69F-4C92-978C-9BFB0F38D820 | ||
IA-64 [49] | 86ED10D5-B607-45BB-8957-D350F23D0571 | ||
LoongArch 64‐bit [49] | F3393B22-E9AF-4613-A948-9D3BFBD0C535 | ||
mips: 32‐bit MIPS big‐endian [49] | 7A430799-F711-4C7E-8E5B-1D685BD48607 | ||
mips64: 64‐bit MIPS big‐endian [49] | 579536F8-6A33-4055-A95A-DF2D5E2C42A8 | ||
mipsel: 32‐bit MIPS little‐endian [49] | D7D150D2-2A04-4A33-8F12-16651205FF7B | ||
mips64el: 64‐bit MIPS little‐endian [49] | 16B417F8-3E06-4F57-8DD2-9B5232F41AA6 | ||
PA-RISC [49] | D212A430-FBC5-49F9-A983-A7FEEF2B8D0E | ||
64‐bit PowerPC little‐endian [49] | 906BD944-4589-4AAE-A4E4-DD983917446A | ||
64‐bit PowerPC big‐endian [49] | 9225A9A3-3C19-4D89-B4F6-EEFF88F17631 | ||
32‐bit PowerPC [49] | 98CFE649-1588-46DC-B2F0-ADD147424925 | ||
RISC-V 32‐bit [49] | AE0253BE-1167-4007-AC68-43926C14C5DE | ||
RISC-V 64‐bit [49] | B6ED5582-440B-4209-B8DA-5FF7C419EA3D | ||
s390 [49] | 7AC63B47-B25C-463B-8DF8-B4A94E6C90E1 | ||
s390x [49] | B325BFBE-C7BE-4AB8-8357-139E652D2F6B | ||
TILE-Gx [49] | 966061EC-28E4-4B2E-B4A5-1F0A825A1D84 | ||
x86-64 [49] | 2C7357ED-EBD2-46D9-AEC1-23D437EC2BF5 | ||
x86 [49] | D13C5D3B-B5D1-422A-B29F-9454FDC89D76 | ||
/usr verity partition for dm-verity | Alpha [49] | 8CCE0D25-C0D0-4A44-BD87-46331BF1DF67 | |
ARC [49] | FCA0598C-D880-4591-8C16-4EDA05C7347C | ||
ARM 32‐bit [49] | C215D751-7BCD-4649-BE90-6627490A4C05 | ||
AArch64 [49] | 6E11A4E7-FBCA-4DED-B9E9-E1A512BB664E | ||
IA-64 [49] | 6A491E03-3BE7-4545-8E38-83320E0EA880 | ||
LoongArch 64‐bit [49] | F46B2C26-59AE-48F0-9106-C50ED47F673D | ||
mips: 32‐bit MIPS big‐endian [49] | 6E5A1BC8-D223-49B7-BCA8-37A5FCCEB996 | ||
mips64: 64‐bit MIPS big‐endian [49] | 81CF9D90-7458-4DF4-8DCF-C8A3A404F09B | ||
mipsel: 32‐bit MIPS little‐endian [49] | 46B98D8D-B55C-4E8F-AAB3-37FCA7F80752 | ||
mips64el: 64‐bit MIPS little‐endian [49] | 3C3D61FE-B5F3-414D-BB71-8739A694A4EF | ||
PA-RISC [49] | 5843D618-EC37-48D7-9F12-CEA8E08768B2 | ||
64‐bit PowerPC little‐endian [49] | EE2B9983-21E8-4153-86D9-B6901A54D1CE | ||
64‐bit PowerPC big‐endian [49] | BDB528A5-A259-475F-A87D-DA53FA736A07 | ||
32‐bit PowerPC [49] | DF765D00-270E-49E5-BC75-F47BB2118B09 | ||
RISC-V 32‐bit [49] | CB1EE4E3-8CD0-4136-A0A4-AA61A32E8730 | ||
RISC-V 64‐bit [49] | 8F1056BE-9B05-47C4-81D6-BE53128E5B54 | ||
s390 [49] | B663C618-E7BC-4D6D-90AA-11B756BB1797 | ||
s390x [49] | 31741CC4-1A2A-4111-A581-E00B447D2D06 | ||
TILE-Gx [49] | 2FB4BF56-07FA-42DA-8132-6B139F2026AE | ||
x86-64 [49] | 77FF5F63-E7B6-4633-ACF4-1565B864C0E6 | ||
x86 [49] | 8F461B0D-14EE-4E81-9AA9-049B6FB97ABD | ||
Root verity signature partition for dm-verity | Alpha [49] | D46495B7-A053-414F-80F7-700C99921EF8 | |
ARC [49] | 143A70BA-CBD3-4F06-919F-6C05683A78BC | ||
ARM 32‐bit [49] | 42B0455F-EB11-491D-98D3-56145BA9D037 | ||
AArch64 [49] | 6DB69DE6-29F4-4758-A7A5-962190F00CE3 | ||
IA-64 [49] | E98B36EE-32BA-4882-9B12-0CE14655F46A | ||
LoongArch 64‐bit [49] | 5AFB67EB-ECC8-4F85-AE8E-AC1E7C50E7D0 | ||
mips: 32‐bit MIPS big‐endian [49] | BBA210A2-9C5D-45EE-9E87-FF2CCBD002D0 | ||
mips64: 64‐bit MIPS big‐endian [49] | 43CE94D4-0F3D-4999-8250-B9DEAFD98E6E | ||
mipsel: 32‐bit MIPS little‐endian [49] | C919CC1F-4456-4EFF-918C-F75E94525CA5 | ||
mips64el: 64‐bit MIPS little‐endian [49] | 904E58EF-5C65-4A31-9C57-6AF5FC7C5DE7 | ||
PA-RISC [49] | 15DE6170-65D3-431C-916E-B0DCD8393F25 | ||
64‐bit PowerPC little‐endian [49] | D4A236E7-E873-4C07-BF1D-BF6CF7F1C3C6 | ||
64‐bit PowerPC big‐endian [49] | F5E2C20C-45B2-4FFA-BCE9-2A60737E1AAF | ||
32‐bit PowerPC [49] | 1B31B5AA-ADD9-463A-B2ED-BD467FC857E7 | ||
RISC-V 32‐bit [49] | 3A112A75-8729-4380-B4CF-764D79934448 | ||
RISC-V 64‐bit [49] | EFE0F087-EA8D-4469-821A-4C2A96A8386A | ||
s390 [49] | 3482388E-4254-435A-A241-766A065F9960 | ||
s390x [49] | C80187A5-73A3-491A-901A-017C3FA953E9 | ||
TILE-Gx [49] | B3671439-97B0-4A53-90F7-2D5A8F3AD47B | ||
x86-64 [49] | 41092B05-9FC8-4523-994F-2DEF0408B176 | ||
x86 [49] | 5996FC05-109C-48DE-808B-23FA0830B676 | ||
/usr verity signature partition for dm-verity | Alpha [49] | 5C6E1C76-076A-457A-A0FE-F3B4CD21CE6E | |
ARC [49] | 94F9A9A1-9971-427A-A400-50CB297F0F35 | ||
ARM 32‐bit [49] | D7FF812F-37D1-4902-A810-D76BA57B975A | ||
AArch64 [49] | C23CE4FF-44BD-4B00-B2D4-B41B3419E02A | ||
IA-64 [49] | 8DE58BC2-2A43-460D-B14E-A76E4A17B47F | ||
LoongArch 64‐bit [49] | B024F315-D330-444C-8461-44BBDE524E99 | ||
mips: 32‐bit MIPS big‐endian [49] | 97AE158D-F216-497B-8057-F7F905770F54 | ||
mips64: 64‐bit MIPS big‐endian [49] | 05816CE2-DD40-4AC6-A61D-37D32DC1BA7D | ||
mipsel: 32‐bit MIPS little‐endian [49] | 3E23CA0B-A4BC-4B4E-8087-5AB6A26AA8A9 | ||
mips64el: 64‐bit MIPS little‐endian [49] | F2C2C7EE-ADCC-4351-B5C6-EE9816B66E16 | ||
PA-RISC [49] | 450DD7D1-3224-45EC-9CF2-A43A346D71EE | ||
64‐bit PowerPC little‐endian [49] | C8BFBD1E-268E-4521-8BBA-BF314C399557 | ||
64‐bit PowerPC big‐endian [49] | 0B888863-D7F8-4D9E-9766-239FCE4D58AF | ||
32‐bit PowerPC [49] | 7007891D-D371-4A80-86A4-5CB875B9302E | ||
RISC-V 32‐bit [49] | C3836A13-3137-45BA-B583-B16C50FE5EB4 | ||
RISC-V 64‐bit [49] | D2F9000A-7A18-453F-B5CD-4D32F77A7B32 | ||
s390 [49] | 17440E4F-A8D0-467F-A46E-3912AE6EF2C5 | ||
s390x [49] | 3F324816-667B-46AE-86EE-9B0C0C6C11B4 | ||
TILE-Gx [49] | 4EDE75E2-6CCC-4CC8-B9C7-70334B087510 | ||
x86-64 [49] | E7BB33FB-06CF-4E81-8273-E543B413E2E2 | ||
x86 [49] | 974A71C0-DE41-43C3-BE5D-5C5CCD1AD2C0 | ||
/boot, as an Extended Boot Loader (XBOOTLDR) partition [49] [50] | BC13C2FF-59E6-4262-A352-B275FD6F7172 | ||
Swap partition [49] [50] | 0657FD6D-A4AB-43C4-84E5-0933C84B4F4F | ||
Logical Volume Manager (LVM) partition | E6D6D379-F507-44C2-A23C-238F2A3DF928 | ||
/home partition [49] [50] | 933AC7E1-2EB4-4F13-B844-0E14E2AEF915 | ||
/srv (server data) partition [49] [50] | 3B8F8425-20E0-4F3B-907F-1A25A76F98E8 | ||
Per‐user home partition [49] | 773F91EF-66D4-49B5-BD83-D683BF40AD16 | ||
Plain dm-crypt partition [53] [54] [55] | 7FFEC5C9-2D00-49B7-8941-3EA10A5586B7 | ||
LUKS partition [53] [54] [55] [56] | CA7D7CCB-63ED-4C53-861C-1742536059CC | ||
Reserved | 8DA63339-0007-60C0-C436-083AC8230908 | ||
GNU/Hurd [57] | Linux filesystem data [58] | 0FC63DAF-8483-4772-8E79-3D69D8477DE4 | |
Linux Swap partition [59] | 0657FD6D-A4AB-43C4-84E5-0933C84B4F4F | ||
FreeBSD | Boot partition [60] | 83BD6B9D-7F41-11DC-BE0B-001560B84F0F | |
BSD disklabel partition [60] | 516E7CB4-6ECF-11D6-8FF8-00022D09712B | ||
Swap partition [60] | 516E7CB5-6ECF-11D6-8FF8-00022D09712B | ||
Unix File System (UFS) partition [60] | 516E7CB6-6ECF-11D6-8FF8-00022D09712B | ||
Vinum volume manager partition [60] | 516E7CB8-6ECF-11D6-8FF8-00022D09712B | ||
ZFS partition [60] | 516E7CBA-6ECF-11D6-8FF8-00022D09712B | ||
nandfs partition [61] | 74BA7DD9-A689-11E1-BD04-00E081286ACF | ||
macOS Darwin | Hierarchical File System Plus (HFS+) partition | 48465300-0000-11AA-AA11-00306543ECAC | |
Apple APFS container APFS FileVault volume container | 7C3457EF-0000-11AA-AA11-00306543ECAC | ||
Apple UFS container | 55465300-0000-11AA-AA11-00306543ECAC | ||
ZFS [j] | 6A898CC3-1DD2-11B2-99A6-080020736631 | ||
Apple RAID partition | 52414944-0000-11AA-AA11-00306543ECAC | ||
Apple RAID partition, offline | 52414944-5F4F-11AA-AA11-00306543ECAC | ||
Apple Boot partition (Recovery HD) | 426F6F74-0000-11AA-AA11-00306543ECAC | ||
Apple Label | 4C616265-6C00-11AA-AA11-00306543ECAC | ||
Apple TV Recovery partition | 5265636F-7665-11AA-AA11-00306543ECAC | ||
Apple Core Storage Container HFS+ FileVault volume container | 53746F72-6167-11AA-AA11-00306543ECAC | ||
Apple APFS Preboot partition | 69646961-6700-11AA-AA11-00306543ECAC | ||
Apple APFS Recovery partition | 52637672-7900-11AA-AA11-00306543ECAC | ||
Solaris illumos | Boot partition | 6A82CB45-1DD2-11B2-99A6-080020736631 | |
Root partition | 6A85CF4D-1DD2-11B2-99A6-080020736631 | ||
Swap partition | 6A87C46F-1DD2-11B2-99A6-080020736631 | ||
Backup partition | 6A8B642B-1DD2-11B2-99A6-080020736631 | ||
/usr partition [j] | 6A898CC3-1DD2-11B2-99A6-080020736631 | ||
/var partition | 6A8EF2E9-1DD2-11B2-99A6-080020736631 | ||
/home partition | 6A90BA39-1DD2-11B2-99A6-080020736631 | ||
Alternate sector | 6A9283A5-1DD2-11B2-99A6-080020736631 | ||
Reserved partition | 6A945A3B-1DD2-11B2-99A6-080020736631 | ||
6A9630D1-1DD2-11B2-99A6-080020736631 | |||
6A980767-1DD2-11B2-99A6-080020736631 | |||
6A96237F-1DD2-11B2-99A6-080020736631 | |||
6A8D2AC7-1DD2-11B2-99A6-080020736631 | |||
NetBSD [62] [k] | Swap partition | 49F48D32-B10E-11DC-B99B-0019D1879648 | |
FFS partition | 49F48D5A-B10E-11DC-B99B-0019D1879648 | ||
LFS partition | 49F48D82-B10E-11DC-B99B-0019D1879648 | ||
RAID partition | 49F48DAA-B10E-11DC-B99B-0019D1879648 | ||
Concatenated partition | 2DB519C4-B10F-11DC-B99B-0019D1879648 | ||
Encrypted partition | 2DB519EC-B10F-11DC-B99B-0019D1879648 | ||
ChromeOS [63] [64] | ChromeOS kernel | FE3A2A5D-4F32-41A7-B725-ACCC3285A309 | |
ChromeOS rootfs | 3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC | ||
ChromeOS firmware | CAB6E88E-ABF3-4102-A07A-D4BB9BE3C1D3 | ||
ChromeOS future use | 2E0A753D-9E48-43B0-8337-B15192CB1B5E | ||
ChromeOS miniOS | 09845860-705F-4BB5-B16C-8A8A099CAF52 | ||
ChromeOS hibernate | 3F0F8318-F146-4E6B-8222-C28C8F02E0D5 | ||
Container Linux by CoreOS [65] | /usr partition (coreos-usr) | 5DFBF5F4-2848-4BAC-AA5E-0D9A20B745A6 | |
Resizable rootfs (coreos-resize) | 3884DD41-8582-4404-B9A8-E9B84F2DF50E | ||
OEM customizations (coreos-reserved) | C95DC21A-DF0E-4340-8D7B-26CBFA9A03E0 | ||
Root filesystem on RAID (coreos-root-raid) | BE9067B9-EA49-4F15-B4F6-F36F8C9E1818 | ||
Haiku [66] | Haiku BFS | 42465331-3BA3-10F1-802A-4861696B7521 | |
MidnightBSD [67] [k] | Boot partition | 85D5E45E-237C-11E1-B4B3-E89A8F7FC3A7 | |
Data partition | 85D5E45A-237C-11E1-B4B3-E89A8F7FC3A7 | ||
Swap partition | 85D5E45B-237C-11E1-B4B3-E89A8F7FC3A7 | ||
Unix File System (UFS) partition | 0394EF8B-237E-11E1-B4B3-E89A8F7FC3A7 | ||
Vinum volume manager partition | 85D5E45C-237C-11E1-B4B3-E89A8F7FC3A7 | ||
ZFS partition | 85D5E45D-237C-11E1-B4B3-E89A8F7FC3A7 | ||
Ceph [l] | Journal | 45B0969E-9B03-4F30-B4C6-B4B80CEFF106 | |
dm-crypt journal | 45B0969E-9B03-4F30-B4C6-5EC00CEFF106 | ||
OSD | 4FBD7E29-9D25-41B8-AFD0-062C0CEFF05D | ||
dm-crypt OSD | 4FBD7E29-9D25-41B8-AFD0-5EC00CEFF05D | ||
Disk in creation | 89C57F98-2FE5-4DC0-89C1-F3AD0CEFF2BE | ||
dm-crypt disk in creation | 89C57F98-2FE5-4DC0-89C1-5EC00CEFF2BE | ||
Block | CAFECAFE-9B03-4F30-B4C6-B4B80CEFF106 | ||
Block DB | 30CD0809-C2B2-499C-8879-2D6B78529876 | ||
Block write-ahead log | 5CE17FCE-4087-4169-B7FF-056CC58473F9 | ||
Lockbox for dm-crypt keys | FB3AABF9-D25F-47CC-BF5E-721D1816496B | ||
Multipath OSD | 4FBD7E29-8AE0-4982-BF9D-5A8D867AF560 | ||
Multipath journal | 45B0969E-8AE0-4982-BF9D-5A8D867AF560 | ||
Multipath block | CAFECAFE-8AE0-4982-BF9D-5A8D867AF560 | ||
Multipath block | 7F4A666A-16F3-47A2-8445-152EF4D03F6C | ||
Multipath block DB | EC6D6385-E346-45DC-BE91-DA2A7C8B3261 | ||
Multipath block write-ahead log | 01B41E1B-002A-453C-9F17-88793989FF8F | ||
dm-crypt block | CAFECAFE-9B03-4F30-B4C6-5EC00CEFF106 | ||
dm-crypt block DB | 93B0052D-02D9-4D8A-A43B-33A3EE4DFBC3 | ||
dm-crypt block write-ahead log | 306E8683-4FE2-4330-B7C0-00A917C16966 | ||
dm-crypt LUKS journal | 45B0969E-9B03-4F30-B4C6-35865CEFF106 | ||
dm-crypt LUKS block | CAFECAFE-9B03-4F30-B4C6-35865CEFF106 | ||
dm-crypt LUKS block DB | 166418DA-C469-4022-ADF4-B30AFD37F176 | ||
dm-crypt LUKS block write-ahead log | 86A32090-3647-40B9-BBBD-38D8C573AA86 | ||
dm-crypt LUKS OSD | 4FBD7E29-9D25-41B8-AFD0-35865CEFF05D | ||
OpenBSD | Data partition | 824CC7A0-36A8-11E3-890A-952519AD3F61 | |
QNX | Power-safe (QNX6) file system [70] | CEF5A9AD-73BC-4601-89F3-CDEEEEE321A1 | |
Plan 9 | Plan 9 partition | C91818F9-8025-47AF-89D2-F030D7000C2C | |
VMware ESX | vmkcore (coredump partition) | 9D275380-40AD-11DB-BF97-000C2911D1B8 | |
VMFS filesystem partition | AA31E02A-400F-11DB-9590-000C2911D1B8 | ||
VMware Reserved | 9198EFFC-31C0-11DB-8F78-000C2911D1B8 | ||
Android-IA [71] [72] [73] [74] | Bootloader | 2568845D-2332-4675-BC39-8FA5A4748D15 | |
Bootloader2 | 114EAFFE-1552-4022-B26E-9B053604CF84 | ||
Boot | 49A4D17F-93A3-45C1-A0DE-F50B2EBE2599 | ||
Recovery | 4177C722-9E92-4AAB-8644-43502BFD5506 | ||
Misc | EF32A33B-A409-486C-9141-9FFB711F6266 | ||
Metadata | 20AC26BE-20B7-11E3-84C5-6CFDB94711E9 | ||
System | 38F428E6-D326-425D-9140-6E0EA133647C | ||
Cache | A893EF21-E428-470A-9E55-0668FD91A2D9 | ||
Data | DC76DDA9-5AC1-491C-AF42-A82591580C0D | ||
Persistent | EBC597D0-2053-4B15-8B64-E0AAC75F4DB1 | ||
Vendor | C5A0AEEC-13EA-11E5-A1B1-001E67CA0C3C | ||
Config | BD59408B-4514-490D-BF12-9878D963F378 | ||
Factory | 8F68CC74-C5E5-48DA-BE91-A0C8C15E9C80 | ||
Factory (alt) [75] | 9FDAA6EF-4B3F-40D2-BA8D-BFF16BFB887B | ||
Fastboot / Tertiary [76] [77] | 767941D0-2085-11E3-AD3B-6CFDB94711E9 | ||
OEM | AC6D7924-EB71-4DF8-B48D-E267B27148FF | ||
Android 6.0+ ARM | Android Meta | 19A710A2-B3CA-11E4-B026-10604B889DCF | |
Android EXT | 193D1EA4-B3CA-11E4-B075-10604B889DCF | ||
Open Network Install Environment (ONIE) | Boot | 7412F7D5-A156-4B13-81DC-867174929325 | |
Config | D4E6E2CD-4469-46F3-B5CB-1BFF57AFC149 | ||
PowerPC | PReP boot | 9E1A2D38-C612-4316-AA26-8B49521E5A8B | |
freedesktop.org OSes (Linux, etc.) | Shared boot loader configuration [78] | BC13C2FF-59E6-4262-A352-B275FD6F7172 | |
Atari TOS | Basic data partition (GEM, BGM, F32) | 734E5AFE-F61A-11E6-BC64-92361F002671 | |
Atari TOS | Raw data partition (RAW), XHDI | 35540011-B055-499F-842D-C69AECA357B7 | |
VeraCrypt | Encrypted data partition | 8C8F8EFF-AC95-4770-814A-21994F2DBC8F | |
OS/2 | ArcaOS Type 1 | 90B6FF38-B98F-4358-A21F-48F35B4A8AD3 | |
Storage Performance Development Kit (SPDK) | SPDK block device [79] | 7C5222BD-8F5D-4087-9C00-BF9843C7B58C | |
barebox bootloader | barebox-state [80] | 4778ED65-BF42-45FA-9C5B-287A1DC4AAB1 | |
U-Boot bootloader | U-Boot environment [81] [82] | 3DE21764-95BD-54BD-A5C3-4ABE786F38A8 | |
SoftRAID[ citation needed ] | SoftRAID_Status | B6FA30DA-92D2-4A9A-96F1-871EC6486200 | |
SoftRAID_Scratch | 2E313465-19B9-463F-8126-8A7993773801 | ||
SoftRAID_Volume | FA709C7E-65B1-4593-BFD5-E71D61DE9B02 | ||
SoftRAID_Cache | BBBA6DF5-F46F-4A89-8F59-8765B2727503 | ||
Fuchsia standard partitions [83] | Bootloader (slot A/B/R) | FE8A2634-5E2E-46BA-99E3-3A192091A350 | |
Durable mutable encrypted system data | D9FD4535-106C-4CEC-8D37-DFC020CA87CB | ||
Durable mutable bootloader data (including A/B/R metadata) | A409E16B-78AA-4ACC-995C-302352621A41 | ||
Factory-provisioned read-only system data | F95D940E-CABA-4578-9B93-BB6C90F29D3E | ||
Factory-provisioned read-only bootloader data | 10B8DBAA-D2BF-42A9-98C6-A7C5DB3701E7 | ||
Fuchsia Volume Manager | 49FD7CB8-DF15-4E73-B9D9-992070127F0F | ||
Verified boot metadata (slot A/B/R) | 421A8BFC-85D9-4D85-ACDA-B64EEC0133E9 | ||
Zircon boot image (slot A/B/R) | 9B37FFF6-2E58-466A-983A-F7926D0B04E0 | ||
Fuchsia legacy partitions [83] [m] | |||
fuchsia-esp | C12A7328-F81F-11D2-BA4B-00A0C93EC93B | ||
fuchsia-system | 606B000B-B7C7-4653-A7D5-B737332C899D | ||
fuchsia-data | 08185F0C-892D-428A-A789-DBEEC8F55E6A | ||
fuchsia-install | 48435546-4953-2041-494E-5354414C4C52 | ||
fuchsia-blob | 2967380E-134C-4CBB-B6DA-17E7CE1CA45D | ||
fuchsia-fvm | 41D0E340-57E3-954E-8C1E-17ECAC44CFF5 | ||
Zircon boot image (slot A) | DE30CC86-1F4A-4A31-93C4-66F147D33E05 | ||
Zircon boot image (slot B) | 23CC04DF-C278-4CE7-8471-897D1A4BCDF7 | ||
Zircon boot image (slot R) | A0E5CF57-2DEF-46BE-A80C-A2067C37CD49 | ||
sys-config | 4E5E989E-4C86-11E8-A15B-480FCF35F8E6 | ||
factory-config | 5A3A90BE-4C86-11E8-A15B-480FCF35F8E6 | ||
bootloader | 5ECE94FE-4C86-11E8-A15B-480FCF35F8E6 | ||
guid-test | 8B94D043-30BE-4871-9DFA-D69556E8C1F3 | ||
Verified boot metadata (slot A) | A13B4D9A-EC5F-11E8-97D8-6C3BE52705BF | ||
Verified boot metadata (slot B) | A288ABF2-EC5F-11E8-97D8-6C3BE52705BF | ||
Verified boot metadata (slot R) | 6A2460C3-CD11-4E8B-80A8-12CCE268ED0A | ||
misc | 1D75395D-F2C6-476B-A8B7-45CC1C97B476 | ||
emmc-boot1 | 900B0FC5-90CD-4D4F-84F9-9F8ED579DB88 | ||
emmc-boot2 | B2B2E8D1-7C10-4EBC-A2D0-4614568260AD | ||
Minix | Minix filesystem | 481B2A38-0561-420B-B72A-F1C4988EFC16 |
ULL
suffix to an integer constant makes it of type unsigned long long int
.C12A7328-F81F-11D2-BA4B-00A0C93EC93B
), when serialized in GPT data structures (little-endian), corresponds to the hex sequence 28 73 2A C1 1F F8 D2 11 BA 4B 00 A0 C9 3E C9 3B
. The first three blocks are byte-swapped to little-endian, the last is a byte array. See details in TN2166 [11] /usr
on Solaris is used as a generic GUID for ZFS by macOS.zircon_{a,b,r}
) share the same type and are distinguished by name and unique GUID. [84] File Allocation Table (FAT) is a file system developed for personal computers and was the default filesystem for the MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. The increase in disk drive capacity over time drove modifications to the design that resulted in versions: FAT12, FAT16, FAT32, and exFAT. FAT was replaced with NTFS as the default file system on Microsoft operating systems starting with Windows XP. Nevertheless, FAT continues to be commonly used on relatively small capacity solid-state storage technologies such as SD card, MultiMediaCard (MMC) and eMMC because of its compatibility and ease of implementation.
Disk partitioning or disk slicing is the creation of one or more regions on secondary storage, so that each region can be managed separately. These regions are called partitions. It is typically the first step of preparing a newly installed disk after a partitioning scheme is chosen for the new disk before any file system is created. The disk stores the information about the partitions' locations and sizes in an area known as the partition table that the operating system reads before any other part of the disk. Each partition then appears to the operating system as a distinct "logical" disk that uses part of the actual disk. System administrators use a program called a partition editor to create, resize, delete, and manipulate the partitions. Partitioning allows the use of different filesystems to be installed for different kinds of files. Separating user data from system data can prevent the system partition from becoming full and rendering the system unusable. Partitioning can also make backing up easier. A disadvantage is that it can be difficult to properly size partitions, resulting in having one partition with too much free space and another nearly totally allocated.
A boot sector is the sector of a persistent data storage device which contains machine code to be loaded into random-access memory (RAM) and then executed by a computer system's built-in firmware.
GNU GRUB is a boot loader package from the GNU Project. GRUB is the reference implementation of the Free Software Foundation's Multiboot Specification, which provides a user the choice to boot one of multiple operating systems installed on a computer or select a specific kernel configuration available on a particular operating system's partitions.
Logical block addressing (LBA) is a common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disk drives. LBA is a particularly simple linear addressing scheme; blocks are located by an integer index, with the first block being LBA 0, the second LBA 1, and so on.
Unified Extensible Firmware Interface is a specification for the firmware architecture of a computing platform. When a computer is powered on, the UEFI-implementation is typically the first that runs, before starting the operating system. Examples include AMI Aptio, Phoenix SecureCore, TianoCore EDK II, InsydeH2O.
Cylinder-head-sector (CHS) is an early method for giving addresses to each physical block of data on a hard disk drive.
INT 13h is shorthand for BIOS interrupt call 13hex, the 20th interrupt vector in an x86-based computer system. The BIOS typically sets up a real mode interrupt handler at this vector that provides sector-based hard disk and floppy disk read and write services using cylinder-head-sector (CHS) addressing. Modern PC BIOSes also include INT 13h extension functions, originated by IBM and Microsoft in 1992, that provide those same disk access services using 64-bit LBA addressing; with minor additions, these were quasi-standardized by Phoenix Technologies and others as the EDD BIOS extensions.
Apple Partition Map (APM) is a partition scheme used to define the low-level organization of data on disks formatted for use with 68k and PowerPC Macintosh computers. It was introduced with the Macintosh II.
The Logical Disk Manager (LDM) 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, Windows 7, Windows 8, Windows 10 and Windows 11. The MMC-based Disk Management snap-in hosts the Logical Disk Manager. On Windows 8 and Windows Server 2012, Microsoft deprecated LDM in favor of Storage Spaces.
An extended boot record (EBR), or extended partition boot record (EPBR), is a descriptor for a logical partition under the common DOS disk drive partitioning system. In that system, when one partition record entry in the master boot record (MBR) is designated an extended partition, then that partition can be subdivided into a number of logical partitions. The actual structure of that extended partition is described by one or more EBRs, which are located inside the extended partition. The first EBR will always be located on the first sector of the extended partition.
TestDisk is a free and open-source data recovery utility that helps users recover lost partitions or repair corrupted filesystems. TestDisk can collect detailed information about a corrupted drive, which can then be sent to a technician for further analysis. TestDisk supports DOS, Microsoft Windows, Linux, FreeBSD, NetBSD, OpenBSD, SunOS, and MacOS. TestDisk handles non-partitioned and partitioned media. In particular, it recognizes the GUID Partition Table (GPT), Apple partition map, PC/Intel BIOS partition tables, Sun Solaris slice and Xbox fixed partitioning scheme. TestDisk uses a command line user interface. TestDisk can recover deleted files with 97% accuracy.
A volume boot record (VBR) is a type of boot sector introduced by the IBM Personal Computer. It may be found on a partitioned data storage device, such as a hard disk, or an unpartitioned device, such as a floppy disk, and contains machine code for bootstrapping programs stored in other parts of the device. On non-partitioned storage devices, it is the first sector of the device. On partitioned devices, it is the first sector of an individual partition on the device, with the first sector of the entire device being a Master Boot Record (MBR) containing the partition table.
A Microsoft Reserved Partition (MSR) is a partition of a data storage device, which is created to reserve a portion of disk space for possible subsequent use by a Windows operating system installed on a separate partition. No meaningful data is stored within the MSR; though from the MSR, chunks may be taken for the creation of new partitions, which themselves may contain data structures.
The EFIsystem partition or ESP is a partition on a data storage device that is used by computers that have the Unified Extensible Firmware Interface (UEFI). When a computer is booted, UEFI firmware loads files stored on the ESP to start operating systems and various utilities.
In Microsoft operating systems, when using basic disk partitioned with GUID Partition Table (GPT) layout, a basic data partition (BDP) is any partition identified with Globally Unique Identifier (GUID) of EBD0A0A2-B9E5-4433-87C0-68B6B72699C7.
The Windows Boot Manager (BOOTMGR
) is the bootloader provided by Microsoft for Windows NT versions starting with Windows Vista and Windows Server 2008. It is the first program launched by the BIOS or UEFI of the computer and is responsible for loading the rest of Windows. It replaced the NTLDR present in older versions of Windows.
The partition type 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.
The BIOS boot partition is a partition on a data storage device that GNU GRUB uses on legacy BIOS-based personal computers in order to boot an operating system, when the actual boot device contains a GUID Partition Table (GPT). Such a layout is sometimes referred to as BIOS/GPT boot.
A master boot record (MBR) is a type of boot sector in the first block of partitioned computer mass storage devices like fixed disks or removable drives intended for use with IBM PC-compatible systems and beyond. The concept of MBRs was publicly introduced in 1983 with PC DOS 2.0.
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