geom/part/gpart.8

.\" Copyright (c) 2007, 2008 Marcel Moolenaar
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.\" $FreeBSD$
.\"
.Dd September 3, 2019
.Dt GPART 8
.Os
.Sh NAME
.Nm gpart
.Nd "control utility for the disk partitioning GEOM class"
.Sh SYNOPSIS
.\" ==== ADD ====
.Nm
.Cm add
.Fl t Ar type
.Op Fl a Ar alignment
.Op Fl b Ar start
.Op Fl s Ar size
.Op Fl i Ar index
.Op Fl l Ar label
.Op Fl f Ar flags
.Ar geom
.\" ==== BACKUP ====
.Nm
.Cm backup
.Ar geom
.\" ==== BOOTCODE ====
.Nm
.Cm bootcode
.Op Fl N
.Op Fl b Ar bootcode
.Op Fl p Ar partcode Fl i Ar index
.Op Fl f Ar flags
.Ar geom
.\" ==== COMMIT ====
.Nm
.Cm commit
.Ar geom
.\" ==== CREATE ====
.Nm
.Cm create
.Fl s Ar scheme
.Op Fl n Ar entries
.Op Fl f Ar flags
.Ar provider
.\" ==== DELETE ====
.Nm
.Cm delete
.Fl i Ar index
.Op Fl f Ar flags
.Ar geom
.\" ==== DESTROY ====
.Nm
.Cm destroy
.Op Fl F
.Op Fl f Ar flags
.Ar geom
.\" ==== MODIFY ====
.Nm
.Cm modify
.Fl i Ar index
.Op Fl l Ar label
.Op Fl t Ar type
.Op Fl f Ar flags
.Ar geom
.\" ==== RECOVER ====
.Nm
.Cm recover
.Op Fl f Ar flags
.Ar geom
.\" ==== RESIZE ====
.Nm
.Cm resize
.Fl i Ar index
.Op Fl a Ar alignment
.Op Fl s Ar size
.Op Fl f Ar flags
.Ar geom
.\" ==== RESTORE ====
.Nm
.Cm restore
.Op Fl lF
.Op Fl f Ar flags
.Ar provider
.Op Ar ...
.\" ==== SET ====
.Nm
.Cm set
.Fl a Ar attrib
.Fl i Ar index
.Op Fl f Ar flags
.Ar geom
.\" ==== SHOW ====
.Nm
.Cm show
.Op Fl l | r
.Op Fl p
.Op Ar geom ...
.\" ==== UNDO ====
.Nm
.Cm undo
.Ar geom
.\" ==== UNSET ====
.Nm
.Cm unset
.Fl a Ar attrib
.Fl i Ar index
.Op Fl f Ar flags
.Ar geom
.\"
.Nm
.Cm list
.Nm
.Cm status
.Nm
.Cm load
.Nm
.Cm unload
.Sh DESCRIPTION
The
.Nm
utility is used to partition GEOM providers, normally disks.
The first argument is the action to be taken:
.Bl -tag -width ".Cm bootcode"
.\" ==== ADD ====
.It Cm add
Add a new partition to the partitioning scheme given by
.Ar geom .
The partition type must be specified with
.Fl t Ar type .
The partition's location, size, and other attributes will be calculated
automatically if the corresponding options are not specified.
.Pp
The
.Cm add
command accepts these options:
.Bl -tag -width 12n
.It Fl a Ar alignment
If specified, then
.Nm
utility tries to align
.Ar start
offset and partition
.Ar size
to be multiple of
.Ar alignment
value.
.It Fl b Ar start
The logical block address where the partition will begin.
A SI unit suffix is allowed.
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl i Ar index
The index in the partition table at which the new partition is to be
placed.
The index determines the name of the device special file used
to represent the partition.
.It Fl l Ar label
The label attached to the partition.
This option is only valid when used on partitioning schemes that support
partition labels.
.It Fl s Ar size
Create a partition of size
.Ar size .
A SI unit suffix is allowed.
.It Fl t Ar type
Create a partition of type
.Ar type .
Partition types are discussed below in the section entitled
.Sx "PARTITION TYPES" .
.El
.\" ==== BACKUP ====
.It Cm backup
Dump a partition table to standard output in a special format used by the
.Cm restore
action.
.\" ==== BOOTCODE ====
.It Cm bootcode
Embed bootstrap code into the partitioning scheme's metadata on the
.Ar geom
(using
.Fl b Ar bootcode )
or write bootstrap code into a partition (using
.Fl p Ar partcode
and
.Fl i Ar index ) .
.Pp
The
.Cm bootcode
command accepts these options:
.Bl -tag -width 10n
.It Fl N
Don't preserve the Volume Serial Number for MBR.
MBR bootcode contains Volume Serial Number by default, and
.Nm
tries to preserve it when installing new bootstrap code.
This option allows to skip the preservation to help with some versions of
.Xr boot0 8
that don't support Volume Serial Number.
.It Fl b Ar bootcode
Embed bootstrap code from the file
.Ar bootcode
into the partitioning scheme's metadata for
.Ar geom .
Not all partitioning schemes have embedded bootstrap code, so the
.Fl b Ar bootcode
option is scheme-specific in nature (see the section entitled
.Sx BOOTSTRAPPING
below).
The
.Ar bootcode
file must match the partitioning scheme's requirements for file content
and size.
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl i Ar index
Specify the target partition for
.Fl p Ar partcode .
.It Fl p Ar partcode
Write the bootstrap code from the file
.Ar partcode
into the
.Ar geom
partition specified by
.Fl i Ar index .
The size of the file must be smaller than the size of the partition.
.El
.\" ==== COMMIT ====
.It Cm commit
Commit any pending changes for geom
.Ar geom .
All actions are committed by default and will not result in
pending changes.
Actions can be modified with the
.Fl f Ar flags
option so that they are not committed, but become pending.
Pending changes are reflected by the geom and the
.Nm
utility, but they are not actually written to disk.
The
.Cm commit
action will write all pending changes to disk.
.\" ==== CREATE ====
.It Cm create
Create a new partitioning scheme on a provider given by
.Ar provider .
The scheme to use must be specified with the
.Fl s Ar scheme
option.
.Pp
The
.Cm create
command accepts these options:
.Bl -tag -width 10n
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl n Ar entries
The number of entries in the partition table.
Every partitioning scheme has a minimum and maximum number of entries.
This option allows tables to be created with a number of entries
that is within the limits.
Some schemes have a maximum equal to the minimum and some schemes have
a maximum large enough to be considered unlimited.
By default, partition tables are created with the minimum number of
entries.
.It Fl s Ar scheme
Specify the partitioning scheme to use.
The kernel must have support for a particular scheme before
that scheme can be used to partition a disk.
.El
.\" ==== DELETE ====
.It Cm delete
Delete a partition from geom
.Ar geom
and further identified by the
.Fl i Ar index
option.
The partition cannot be actively used by the kernel.
.Pp
The
.cm delete
command accepts these options:
.Bl -tag -width 10n
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl i Ar index
Specifies the index of the partition to be deleted.
.El
.\" ==== DESTROY ====
.It Cm destroy
Destroy the partitioning scheme as implemented by geom
.Ar geom .
.Pp
The
.Cm destroy
command accepts these options:
.Bl -tag -width 10n
.It Fl F
Forced destroying of the partition table even if it is not empty.
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.El
.\" ==== MODIFY ====
.It Cm modify
Modify a partition from geom
.Ar geom
and further identified by the
.Fl i Ar index
option.
Only the type and/or label of the partition can be modified.
Not all partitioning schemes support labels and it is invalid to
try to change a partition label in such cases.
.Pp
The
.Cm modify
command accepts these options:
.Bl -tag -width 10n
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl i Ar index
Specifies the index of the partition to be modified.
.It Fl l Ar label
Change the partition label to
.Ar label .
.It Fl t Ar type
Change the partition type to
.Ar type .
.El
.\" ==== RECOVER ====
.It Cm recover
Recover a corrupt partition's scheme metadata on the geom
.Ar geom .
See the section entitled
.Sx RECOVERING
below for the additional information.
.Pp
The
.Cm recover
command accepts these options:
.Bl -tag -width 10n
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.El
.\" ==== RESIZE ====
.It Cm resize
Resize a partition from geom
.Ar geom
and further identified by the
.Fl i Ar index
option.
If the new size is not specified it is automatically calculated
to be the maximum available from
.Ar geom .
.Pp
The
.Cm resize
command accepts these options:
.Bl -tag -width 12n
.It Fl a Ar alignment
If specified, then
.Nm
utility tries to align partition
.Ar size
to be a multiple of the
.Ar alignment
value.
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl i Ar index
Specifies the index of the partition to be resized.
.It Fl s Ar size
Specifies the new size of the partition, in logical blocks.
A SI unit suffix is allowed.
.El
.\" ==== RESTORE ====
.It Cm restore
Restore the partition table from a backup previously created by the
.Cm backup
action and read from standard input.
Only the partition table is restored.
This action does not affect the content of partitions.
After restoring the partition table and writing bootcode if needed,
user data must be restored from backup.
.Pp
The
.Cm restore
command accepts these options:
.Bl -tag -width 10n
.It Fl F
Destroy partition table on the given
.Ar provider
before doing restore.
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl l
Restore partition labels for partitioning schemes that support them.
.El
.\" ==== SET ====
.It Cm set
Set the named attribute on the partition entry.
See the section entitled
.Sx ATTRIBUTES
below for a list of available attributes.
.Pp
The
.Cm set
command accepts these options:
.Bl -tag -width 10n
.It Fl a Ar attrib
Specifies the attribute to set.
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl i Ar index
Specifies the index of the partition on which the attribute will be set.
.El
.\" ==== SHOW ====
.It Cm show
Show current partition information for the specified geoms, or all
geoms if none are specified.
The default output includes the logical starting block of each
partition, the partition size in blocks, the partition index number,
the partition type, and a human readable partition size.
Block sizes and locations are based on the device's Sectorsize
as shown by
.Cm gpart list .
.Pp
The
.Cm show
command accepts these options:
.Bl -tag -width 10n
.It Fl l
For partitioning schemes that support partition labels, print them
instead of partition type.
.It Fl p
Show provider names instead of partition indexes.
.It Fl r
Show raw partition type instead of symbolic name.
.El
.\" ==== UNDO ====
.It Cm undo
Revert any pending changes for geom
.Ar geom .
This action is the opposite of the
.Cm commit
action and can be used to undo any changes that have not been committed.
.\" ==== UNSET ====
.It Cm unset
Clear the named attribute on the partition entry.
See the section entitled
.Sx ATTRIBUTES
below for a list of available attributes.
.Pp
The
.Cm unset
command accepts these options:
.Bl -tag -width 10n
.It Fl a Ar attrib
Specifies the attribute to clear.
.It Fl f Ar flags
Additional operational flags.
See the section entitled
.Sx "OPERATIONAL FLAGS"
below for a discussion
about its use.
.It Fl i Ar index
Specifies the index of the partition on which the attribute will be cleared.
.El
.It Cm list
See
.Xr geom 8 .
.It Cm status
See
.Xr geom 8 .
.It Cm load
See
.Xr geom 8 .
.It Cm unload
See
.Xr geom 8 .
.El
.Sh PARTITIONING SCHEMES
Several partitioning schemes are supported by the
.Nm
utility:
.Bl -tag -width ".Cm VTOC8"
.It Cm APM
Apple Partition Map, used by PowerPC(R) Macintosh(R) computers.
Requires the
.Cd GEOM_PART_APM
kernel option.
.It Cm BSD
Traditional BSD disklabel, usually used to subdivide MBR partitions.
.Po
This scheme can also be used as the sole partitioning method, without
an MBR.
Partition editing tools from other operating systems often do not
understand the bare disklabel partition layout, so this is sometimes
called
.Dq dangerously dedicated .
.Pc
Requires the
.Cm GEOM_PART_BSD
kernel option.
.It Cm BSD64
64-bit implementation of BSD disklabel used in DragonFlyBSD to subdivide MBR
or GPT partitions.
Requires the
.Cm GEOM_PART_BSD64
kernel option.
.It Cm LDM
The Logical Disk Manager is an implementation of volume manager for
Microsoft Windows NT.
Requires the
.Cd GEOM_PART_LDM
kernel option.
.It Cm GPT
GUID Partition Table is used on Intel-based Macintosh computers and
gradually replacing MBR on most PCs and other systems.
Requires the
.Cm GEOM_PART_GPT
kernel option.
.It Cm MBR
Master Boot Record is used on PCs and removable media.
Requires the
.Cm GEOM_PART_MBR
kernel option.
The
.Cm GEOM_PART_EBR
option adds support for the Extended Boot Record (EBR),
which is used to define a logical partition.
The
.Cm GEOM_PART_EBR_COMPAT
option enables backward compatibility for partition names
in the EBR scheme.
It also prevents any type of actions on such partitions.
.It Cm VTOC8
Sun's SMI Volume Table Of Contents, used by
.Tn SPARC64
and
.Tn UltraSPARC
computers.
Requires the
.Cm GEOM_PART_VTOC8
kernel option.
.El
.Sh PARTITION TYPES
Partition types are identified on disk by particular strings or magic
values.
The
.Nm
utility uses symbolic names for common partition types so the user
does not need to know these values or other details of the partitioning
scheme in question.
The
.Nm
utility also allows the user to specify scheme-specific partition types
for partition types that do not have symbolic names.
Symbolic names currently understood and used by
.Fx
are:
.Bl -tag -width ".Cm dragonfly-disklabel64"
.It Cm apple-boot
The system partition dedicated to storing boot loaders on some Apple
systems.
The scheme-specific types are
.Qq Li "!171"
for MBR,
.Qq Li "!Apple_Bootstrap"
for APM, and
.Qq Li "!426f6f74-0000-11aa-aa11-00306543ecac"
for GPT.
.It Cm bios-boot
The system partition dedicated to second stage of the boot loader program.
Usually it is used by the GRUB 2 loader for GPT partitioning schemes.
The scheme-specific type is
.Qq Li "!21686148-6449-6E6F-744E-656564454649" .
.It Cm efi
The system partition for computers that use the Extensible Firmware
Interface (EFI).
The scheme-specific types are
.Qq Li "!239"
for MBR, and
.Qq Li "!c12a7328-f81f-11d2-ba4b-00a0c93ec93b"
for GPT.
.It Cm freebsd
A
.Fx
partition subdivided into filesystems with a
.Bx
disklabel.
This is a legacy partition type and should not be used for the APM
or GPT schemes.
The scheme-specific types are
.Qq Li "!165"
for MBR,
.Qq Li "!FreeBSD"
for APM, and
.Qq Li "!516e7cb4-6ecf-11d6-8ff8-00022d09712b"
for GPT.
.It Cm freebsd-boot
A
.Fx
partition dedicated to bootstrap code.
The scheme-specific type is
.Qq Li "!83bd6b9d-7f41-11dc-be0b-001560b84f0f"
for GPT.
.It Cm freebsd-swap
A
.Fx
partition dedicated to swap space.
The scheme-specific types are
.Qq Li "!FreeBSD-swap"
for APM,
.Qq Li "!516e7cb5-6ecf-11d6-8ff8-00022d09712b"
for GPT, and tag 0x0901 for VTOC8.
.It Cm freebsd-ufs
A
.Fx
partition that contains a UFS or UFS2 filesystem.
The scheme-specific types are
.Qq Li "!FreeBSD-UFS"
for APM,
.Qq Li "!516e7cb6-6ecf-11d6-8ff8-00022d09712b"
for GPT, and tag 0x0902 for VTOC8.
.It Cm freebsd-vinum
A
.Fx
partition that contains a Vinum volume.
The scheme-specific types are
.Qq Li "!FreeBSD-Vinum"
for APM,
.Qq Li "!516e7cb8-6ecf-11d6-8ff8-00022d09712b"
for GPT, and tag 0x0903 for VTOC8.
.It Cm freebsd-zfs
A
.Fx
partition that contains a ZFS volume.
The scheme-specific types are
.Qq Li "!FreeBSD-ZFS"
for APM,
.Qq Li "!516e7cba-6ecf-11d6-8ff8-00022d09712b"
for GPT, and 0x0904 for VTOC8.
.El
.Pp
Other symbolic names that can be used with
.Cm gpart
utility are:
.Bl -tag -width ".Cm dragonfly-disklabel64"
.It Cm apple-apfs
An Apple macOS partition used for the Apple file system, APFS.
.It Cm apple-core-storage
An Apple Mac OS X partition used by logical volume manager known as
Core Storage.
The scheme-specific type is
.Qq Li "!53746f72-6167-11aa-aa11-00306543ecac"
for GPT.
.It Cm apple-hfs
An Apple Mac OS X partition that contains a HFS or HFS+ filesystem.
The scheme-specific types are
.Qq Li "!175"
for MBR,
.Qq Li "!Apple_HFS"
for APM and
.Qq Li "!48465300-0000-11aa-aa11-00306543ecac"
for GPT.
.It Cm apple-label
An Apple Mac OS X partition dedicated to partition metadata that descibes
disk device.
The scheme-specific type is
.Qq Li "!4c616265-6c00-11aa-aa11-00306543ecac"
for GPT.
.It Cm apple-raid
An Apple Mac OS X partition used in a software RAID configuration.
The scheme-specific type is
.Qq Li "!52414944-0000-11aa-aa11-00306543ecac"
for GPT.
.It Cm apple-raid-offline
An Apple Mac OS X partition used in a software RAID configuration.
The scheme-specific type is
.Qq Li "!52414944-5f4f-11aa-aa11-00306543ecac"
for GPT.
.It Cm apple-tv-recovery
An Apple Mac OS X partition used by Apple TV.
The scheme-specific type is
.Qq Li "!5265636f-7665-11aa-aa11-00306543ecac"
for GPT.
.It Cm apple-ufs
An Apple Mac OS X partition that contains a UFS filesystem.
The scheme-specific types are
.Qq Li "!168"
for MBR,
.Qq Li "!Apple_UNIX_SVR2"
for APM and
.Qq Li "!55465300-0000-11aa-aa11-00306543ecac"
for GPT.
.It Cm dragonfly-label32
A DragonFlyBSD partition subdivided into filesystems with a
.Bx
disklabel.
The scheme-specific type is
.Qq Li "!9d087404-1ca5-11dc-8817-01301bb8a9f5"
for GPT.
.It Cm dragonfly-label64
A DragonFlyBSD partition subdivided into filesystems with a
disklabel64.
The scheme-specific type is
.Qq Li "!3d48ce54-1d16-11dc-8696-01301bb8a9f5"
for GPT.
.It Cm dragonfly-legacy
A legacy partition type used in DragonFlyBSD.
The scheme-specific type is
.Qq Li "!bd215ab2-1d16-11dc-8696-01301bb8a9f5"
for GPT.
.It Cm dragonfly-ccd
A DragonFlyBSD partition used with Concatenated Disk driver.
The scheme-specific type is
.Qq Li "!dbd5211b-1ca5-11dc-8817-01301bb8a9f5"
for GPT.
.It Cm dragonfly-hammer
A DragonFlyBSD partition that contains a Hammer filesystem.
The scheme-specific type is
.Qq Li "!61dc63ac-6e38-11dc-8513-01301bb8a9f5"
for GPT.
.It Cm dragonfly-hammer2
A DragonFlyBSD partition that contains a Hammer2 filesystem.
The scheme-specific type is
.Qq Li "!5cbb9ad1-862d-11dc-a94d-01301bb8a9f5"
for GPT.
.It Cm dragonfly-swap
A DragonFlyBSD partition dedicated to swap space.
The scheme-specific type is
.Qq Li "!9d58fdbd-1ca5-11dc-8817-01301bb8a9f5"
for GPT.
.It Cm dragonfly-ufs
A DragonFlyBSD partition that contains an UFS1 filesystem.
The scheme-specific type is
.Qq Li "!9d94ce7c-1ca5-11dc-8817-01301bb8a9f5"
for GPT.
.It Cm dragonfly-vinum
A DragonFlyBSD partition used with Logical Volume Manager.
The scheme-specific type is
.Qq Li "!9dd4478f-1ca5-11dc-8817-01301bb8a9f5"
for GPT.
.It Cm ebr
A partition subdivided into filesystems with a EBR.
The scheme-specific type is
.Qq Li "!5"
for MBR.
.It Cm fat16
A partition that contains a FAT16 filesystem.
The scheme-specific type is
.Qq Li "!6"
for MBR.
.It Cm fat32
A partition that contains a FAT32 filesystem.
The scheme-specific type is
.Qq Li "!11"
for MBR.
.It Cm fat32lba
A partition that contains a FAT32 (LBA) filesystem.
The scheme-specific type is
.Qq Li "!12"
for MBR.
.It Cm linux-data
A Linux partition that contains some filesystem with data.
The scheme-specific types are
.Qq Li "!131"
for MBR and
.Qq Li "!0fc63daf-8483-4772-8e79-3d69d8477de4"
for GPT.
.It Cm linux-lvm
A Linux partition dedicated to Logical Volume Manager.
The scheme-specific types are
.Qq Li "!142"
for MBR and
.Qq Li "!e6d6d379-f507-44c2-a23c-238f2a3df928"
for GPT.
.It Cm linux-raid
A Linux partition used in a software RAID configuration.
The scheme-specific types are
.Qq Li "!253"
for MBR and
.Qq Li "!a19d880f-05fc-4d3b-a006-743f0f84911e"
for GPT.
.It Cm linux-swap
A Linux partition dedicated to swap space.
The scheme-specific types are
.Qq Li "!130"
for MBR and
.Qq Li "!0657fd6d-a4ab-43c4-84e5-0933c84b4f4f"
for GPT.
.It Cm mbr
A partition that is sub-partitioned by a Master Boot Record (MBR).
This type is known as
.Qq Li "!024dee41-33e7-11d3-9d69-0008c781f39f"
by GPT.
.It Cm ms-basic-data
A basic data partition (BDP) for Microsoft operating systems.
In the GPT this type is the equivalent to partition types
.Cm fat16 , fat32
and
.Cm ntfs
in MBR.
The scheme-specific type is
.Qq Li "!ebd0a0a2-b9e5-4433-87c0-68b6b72699c7"
for GPT.
.It Cm ms-ldm-data
A partition that contains Logical Disk Manager (LDM) volumes.
The scheme-specific types are
.Qq Li "!66"
for MBR,
.Qq Li "!af9b60a0-1431-4f62-bc68-3311714a69ad"
for GPT.
.It Cm ms-ldm-metadata
A partition that contains Logical Disk Manager (LDM) database.
The scheme-specific type is
.Qq Li "!5808c8aa-7e8f-42e0-85d2-e1e90434cfb3"
for GPT.
.It Cm netbsd-ccd
A NetBSD partition used with Concatenated Disk driver.
The scheme-specific type is
.Qq Li "!2db519c4-b10f-11dc-b99b-0019d1879648"
for GPT.
.It Cm netbsd-cgd
An encrypted NetBSD partition.
The scheme-specific type is
.Qq Li "!2db519ec-b10f-11dc-b99b-0019d1879648"
for GPT.
.It Cm netbsd-ffs
A NetBSD partition that contains an UFS filesystem.
The scheme-specific type is
.Qq Li "!49f48d5a-b10e-11dc-b99b-0019d1879648"
for GPT.
.It Cm netbsd-lfs
A NetBSD partition that contains an LFS filesystem.
The scheme-specific type is
.Qq Li "!49f48d82-b10e-11dc-b99b-0019d1879648"
for GPT.
.It Cm netbsd-raid
A NetBSD partition used in a software RAID configuration.
The scheme-specific type is
.Qq Li "!49f48daa-b10e-11dc-b99b-0019d1879648"
for GPT.
.It Cm netbsd-swap
A NetBSD partition dedicated to swap space.
The scheme-specific type is
.Qq Li "!49f48d32-b10e-11dc-b99b-0019d1879648"
for GPT.
.It Cm ntfs
A partition that contains a NTFS or exFAT filesystem.
The scheme-specific type is
.Qq Li "!7"
for MBR.
.It Cm prep-boot
The system partition dedicated to storing boot loaders on some PowerPC systems,
notably those made by IBM.
The scheme-specific types are
.Qq Li "!65"
for MBR and
.Qq Li "!0x9e1a2d38-c612-4316-aa26-8b49521e5a8b"
for GPT.
.It Cm vmware-vmfs
A partition that contains a VMware File System (VMFS).
The scheme-specific types are
.Qq Li "!251"
for MBR and
.Qq Li "!aa31e02a-400f-11db-9590-000c2911d1b8"
for GPT.
.It Cm vmware-vmkdiag
A partition that contains a VMware diagostic filesystem.
The scheme-specific types are
.Qq Li "!252"
for MBR and
.Qq Li "!9d275380-40ad-11db-bf97-000c2911d1b8"
for GPT.
.It Cm vmware-reserved
A VMware reserved partition.
The scheme-specific type is
.Qq Li "!9198effc-31c0-11db-8f-78-000c2911d1b8"
for GPT.
.It Cm vmware-vsanhdr
A partition claimed by VMware VSAN.
The scheme-specific type is
.Qq Li "!381cfccc-7288-11e0-92ee-000c2911d0b2"
for GPT.
.El
.Sh ATTRIBUTES
The scheme-specific attributes for EBR:
.Bl -tag -width ".Cm active"
.It Cm active
.El
.Pp
The scheme-specific attributes for GPT:
.Bl -tag -width ".Cm bootfailed"
.It Cm bootme
When set, the
.Nm gptboot
stage 1 boot loader will try to boot the system from this partition.
Multiple partitions can be marked with the
.Cm bootme
attribute.
See
.Xr gptboot 8
for more details.
.It Cm bootonce
Setting this attribute automatically sets the
.Cm bootme
attribute.
When set, the
.Nm gptboot
stage 1 boot loader will try to boot the system from this partition only once.
Multiple partitions can be marked with the
.Cm bootonce
and
.Cm bootme
attribute pairs.
See
.Xr gptboot 8
for more details.
.It Cm bootfailed
This attribute should not be manually managed.
It is managed by the
.Nm gptboot
stage 1 boot loader and the
.Pa /etc/rc.d/gptboot
start-up script.
See
.Xr gptboot 8
for more details.
.It Cm lenovofix
Setting this attribute overwrites the Protective MBR with a new one where
the 0xee partition is the second, rather than the first record.
This resolves a BIOS compatibility issue with some Lenovo models including the
X220, T420, and T520, allowing them to boot from GPT partitioned disks
without using EFI.
.El
.Pp
The scheme-specific attributes for MBR:
.Bl -tag -width ".Cm active"
.It Cm active
.El
.Sh BOOTSTRAPPING
.Fx
supports several partitioning schemes and each scheme uses different
bootstrap code.
The bootstrap code is located in a specific disk area for each partitioning
scheme, and may vary in size for different schemes.
.Pp
Bootstrap code can be separated into two types.
The first type is embedded in the partitioning scheme's metadata, while the
second type is located on a specific partition.
Embedding bootstrap code should only be done with the
.Cm gpart bootcode
command with the
.Fl b Ar bootcode
option.
The GEOM PART class knows how to safely embed bootstrap code into
specific partitioning scheme metadata without causing any damage.
.Pp
The Master Boot Record (MBR) uses a 512-byte bootstrap code image, embedded
into the partition table's metadata area.
There are two variants of this bootstrap code:
.Pa /boot/mbr
and
.Pa /boot/boot0 .
.Pa /boot/mbr
searches for a partition with the
.Cm active
attribute (see the
.Sx ATTRIBUTES
section) in the partition table.
Then it runs next bootstrap stage.
The
.Pa /boot/boot0
image contains a boot manager with some additional interactive functions
for multi-booting from a user-selected partition.
.Pp
A BSD disklabel is usually created inside an MBR partition (slice)
with type
.Cm freebsd
(see the
.Sx "PARTITION TYPES"
section).
It uses 8 KB size bootstrap code image
.Pa /boot/boot ,
embedded into the partition table's metadata area.
.Pp
Both types of bootstrap code are used to boot from the GUID Partition Table.
First, a protective MBR is embedded into the first disk sector from the
.Pa /boot/pmbr
image.
It searches through the GPT for a
.Cm freebsd-boot
partition (see the
.Sx "PARTITION TYPES"
section) and runs the next bootstrap stage from it.
The
.Cm freebsd-boot
partition should be smaller than 545 KB.
It can be located either before or after other
.Fx
partitions on the disk.
There are two variants of bootstrap code to write to this partition:
.Pa /boot/gptboot
and
.Pa /boot/gptzfsboot .
.Pp
.Pa /boot/gptboot
is used to boot from UFS partitions.
.Cm gptboot
searches through
.Cm freebsd-ufs
partitions in the GPT and selects one to boot based on the
.Cm bootonce
and
.Cm bootme
attributes.
If neither attribute is found,
.Pa /boot/gptboot
boots from the first
.Cm freebsd-ufs
partition.
.Pa /boot/loader
.Pq the third bootstrap stage
is loaded from the first partition that matches these conditions.
See
.Xr gptboot 8
for more information.
.Pp
.Pa /boot/gptzfsboot
is used to boot from ZFS.
It searches through the GPT for
.Cm freebsd-zfs
partitions, trying to detect ZFS pools.
After all pools are detected,
.Pa /boot/loader
is started from the first one found set as bootable.
.Pp
The VTOC8 scheme does not support embedding bootstrap code.
Instead, the 8 KBytes bootstrap code image
.Pa /boot/boot1
should be written with the
.Cm gpart bootcode
command with the
.Fl p Ar bootcode
option to all sufficiently large VTOC8 partitions.
To do this the
.Fl i Ar index
option could be omitted.
.Pp
The APM scheme also does not support embedding bootstrap code.
Instead, the 800 KBytes bootstrap code image
.Pa /boot/boot1.hfs
should be written with the
.Cm gpart bootcode
command to a partition of type
.Cm apple-boot ,
which should also be 800 KB in size.
.Sh OPERATIONAL FLAGS
Actions other than the
.Cm commit
and
.Cm undo
actions take an optional
.Fl f Ar flags
option.
This option is used to specify action-specific operational flags.
By default, the
.Nm
utility defines the
.Ql C
flag so that the action is immediately
committed.
The user can specify
.Dq Fl f Cm x
to have the action result in a pending change that can later, with
other pending changes, be committed as a single compound change with
the
.Cm commit
action or reverted with the
.Cm undo
action.
.Sh RECOVERING
The GEOM PART class supports recovering of partition tables only for GPT.
The GPT primary metadata is stored at the beginning of the device.
For redundancy, a secondary
.Pq backup
copy of the metadata is stored at the end of the device.
As a result of having two copies, some corruption of metadata is not
fatal to the working of GPT.
When the kernel detects corrupt metadata, it marks this table as corrupt
and reports the problem.
.Cm destroy
and
.Cm recover
are the only operations allowed on corrupt tables.
.Pp
If one GPT header appears to be corrupt but the other copy remains intact,
the kernel will log the following:
.Bd -literal -offset indent
GEOM: provider: the primary GPT table is corrupt or invalid.
GEOM: provider: using the secondary instead -- recovery strongly advised.
.Ed
.Pp
or
.Bd -literal -offset indent
GEOM: provider: the secondary GPT table is corrupt or invalid.
GEOM: provider: using the primary only -- recovery suggested.
.Ed
.Pp
Also
.Nm
commands such as
.Cm show , status
and
.Cm list
will report about corrupt tables.
.Pp
If the size of the device has changed (e.g.,\& volume expansion) the
secondary GPT header will no longer be located in the last sector.
This is not a metadata corruption, but it is dangerous because any
corruption of the primary GPT will lead to loss of the partition table.
This problem is reported by the kernel with the message:
.Bd -literal -offset indent
GEOM: provider: the secondary GPT header is not in the last LBA.
.Ed
.Pp
This situation can be recovered with the
.Cm recover
command.
This command reconstructs the corrupt metadata using known valid
metadata and relocates the secondary GPT to the end of the device.
.Pp
.Em NOTE :
The GEOM PART class can detect the same partition table visible through
different GEOM providers, and some of them will be marked as corrupt.
Be careful when choosing a provider for recovery.
If you choose incorrectly you can destroy the metadata of another GEOM class,
e.g.,\& GEOM MIRROR or GEOM LABEL.
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 8
variables can be used to control the behavior of the
.Nm PART
GEOM class.
The default value is shown next to each variable.
.Bl -tag -width indent
.It Va kern.geom.part.allow_nesting : No 0
By default, some schemes (currently BSD, BSD64 and VTOC8) do not permit
further nested partitioning.
This variable overrides this restriction and allows arbitrary nesting (except
within partitions created at offset 0).
Some schemes have their own separate checks, for which see below.
.It Va kern.geom.part.auto_resize : No 1
This variable controls automatic resize behavior of
.Nm
GEOM class.
When this variable is enable and new size of provider is detected, the schema
metadata is resized but all changes are not saved to disk, until
.Cm gpart commit
is run to confirm changes.
This behavior is also reported with diagnostic message:
.Sy "GEOM_PART: (provider) was automatically resized."
.Sy "Use `gpart commit (provider)` to save changes or `gpart undo (provider)`"
.Sy "to revert them."
.It Va kern.geom.part.check_integrity : No 1
This variable controls the behaviour of metadata integrity checks.
When integrity checks are enabled, the
.Nm PART
GEOM class verifies all generic partition parameters obtained from the
disk metadata.
If some inconsistency is detected, the partition table will be
rejected with a diagnostic message:
.Sy "GEOM_PART: Integrity check failed (provider, scheme)" .
.It Va kern.geom.part.gpt.allow_nesting : No 0
By default the GPT scheme is allowed only at the outermost nesting level.
This variable allows this restriction to be removed.
.It Va kern.geom.part.ldm.debug : No 0
Debug level of the Logical Disk Manager (LDM) module.
This can be set to a number between 0 and 2 inclusive.
If set to 0 minimal debug information is printed,
and if set to 2 the maximum amount of debug information is printed.
.It Va kern.geom.part.ldm.show_mirrors : No 0
This variable controls how the Logical Disk Manager (LDM) module handles
mirrored volumes.
By default mirrored volumes are shown as partitions with type
.Cm ms-ldm-data
(see the
.Sx "PARTITION TYPES"
section).
If this variable set to 1 each component of the mirrored volume will be
present as independent partition.
.Em NOTE :
This may break a mirrored volume and lead to data damage.
.It Va kern.geom.part.mbr.enforce_chs : No 0
Specify how the Master Boot Record (MBR) module does alignment.
If this variable is set to a non-zero value, the module will automatically
recalculate the user-specified offset and size for alignment with the CHS
geometry.
Otherwise the values will be left unchanged.
.El
.Sh EXIT STATUS
Exit status is 0 on success, and 1 if the command fails.
.Sh EXAMPLES
The examples below assume that the disk's logical block size is 512
bytes, regardless of its physical block size.
.Ss GPT
In this example, we will format
.Pa ada0
with the GPT scheme and create boot, swap and root partitions.
First, we need to create the partition table:
.Bd -literal -offset indent
/sbin/gpart create -s GPT ada0
.Ed
.Pp
Next, we install a protective MBR with the first-stage bootstrap code.
The protective MBR lists a single, bootable partition spanning the
entire disk, thus allowing non-GPT-aware BIOSes to boot from the disk
and preventing tools which do not understand the GPT scheme from
considering the disk to be unformatted.
.Bd -literal -offset indent
/sbin/gpart bootcode -b /boot/pmbr ada0
.Ed
.Pp
We then create a dedicated
.Cm freebsd-boot
partition to hold the second-stage boot loader, which will load the
.Fx
kernel and modules from a UFS or ZFS filesystem.
This partition must be larger than the bootstrap code
.Po
either
.Pa /boot/gptboot
for UFS or
.Pa /boot/gptzfsboot
for ZFS
.Pc ,
but smaller than 545 kB since the first-stage loader will load the
entire partition into memory during boot, regardless of how much data
it actually contains.
We create a 472-block (236 kB) boot partition at offset 40, which is
the size of the partition table (34 blocks or 17 kB) rounded up to the
nearest 4 kB boundary.
.Bd -literal -offset indent
/sbin/gpart add -b 40 -s 472 -t freebsd-boot ada0
/sbin/gpart bootcode -p /boot/gptboot -i 1 ada0
.Ed
.Pp
We now create a 4 GB swap partition at the first available offset,
which is 40 + 472 = 512 blocks (256 kB).
.Bd -literal -offset indent
/sbin/gpart add -s 4G -t freebsd-swap ada0
.Ed
.Pp
Aligning the swap partition and all subsequent partitions on a 256 kB
boundary ensures optimal performance on a wide range of media, from
plain old disks with 512-byte blocks, through modern
.Dq advanced format
disks with 4096-byte physical blocks, to RAID volumes with stripe
sizes of up to 256 kB.
.Pp
Finally, we create and format an 8 GB
.Cm freebsd-ufs
partition for the root filesystem, leaving the rest of the slice free
for additional filesystems:
.Bd -literal -offset indent
/sbin/gpart add -s 8G -t freebsd-ufs ada0
/sbin/newfs -Uj /dev/ada0p3
.Ed
.Ss MBR
In this example, we will format
.Pa ada0
with the MBR scheme and create a single partition which we subdivide
using a traditional
.Bx
disklabel.
.Pp
First, we create the partition table and a single 64 GB partition,
then we mark that partition active (bootable) and install the
first-stage boot loader:
.Bd -literal -offset indent
/sbin/gpart create -s MBR ada0
/sbin/gpart add -t freebsd -s 64G ada0
/sbin/gpart set -a active -i 1 ada0
/sbin/gpart bootcode -b /boot/boot0 ada0
.Ed
.Pp
Next, we create a disklabel in that partition
.Po
.Dq slice
in disklabel terminology
.Pc
with room for up to 20 partitions:
.Bd -literal -offset indent
/sbin/gpart create -s BSD -n 20 ada0s1
.Ed
.Pp
We then create an 8 GB root partition and a 4 GB swap partition:
.Bd -literal -offset indent
/sbin/gpart add -t freebsd-ufs -s 8G ada0s1
/sbin/gpart add -t freebsd-swap -s 4G ada0s1
.Ed
.Pp
Finally, we install the appropriate boot loader for the
.Bx
label:
.Bd -literal -offset indent
/sbin/gpart bootcode -b /boot/boot ada0s1
.Ed
.Ss VTOC8
.Pp
Create a VTOC8 scheme on
.Pa da0 :
.Bd -literal -offset indent
/sbin/gpart create -s VTOC8 da0
.Ed
.Pp
Create a 512MB-sized
.Cm freebsd-ufs
partition to contain a UFS filesystem from which the system can boot.
.Bd -literal -offset indent
/sbin/gpart add -s 512M -t freebsd-ufs da0
.Ed
.Pp
Create a 15GB-sized
.Cm freebsd-ufs
partition to contain a UFS filesystem and aligned on 4KB boundaries:
.Bd -literal -offset indent
/sbin/gpart add -s 15G -t freebsd-ufs -a 4k da0
.Ed
.Pp
After creating all required partitions, embed bootstrap code into them:
.Bd -literal -offset indent
/sbin/gpart bootcode -p /boot/boot1 da0
.Ed
.Ss Deleting Partitions and Destroying the Partitioning Scheme
If a
.Em "Device busy"
error is shown when trying to destroy a partition table, remember that
all of the partitions must be deleted first with the
.Cm delete
action.
In this example,
.Pa da0
has three partitions:
.Bd -literal -offset indent
/sbin/gpart delete -i 3 da0
/sbin/gpart delete -i 2 da0
/sbin/gpart delete -i 1 da0
/sbin/gpart destroy da0
.Ed
.Pp
Rather than deleting each partition and then destroying the partitioning
scheme, the
.Fl F
option can be given with
.Cm destroy
to delete all of the partitions before destroying the partitioning scheme.
This is equivalent to the previous example:
.Bd -literal -offset indent
/sbin/gpart destroy -F da0
.Ed
.Ss Backup and Restore
.Pp
Create a backup of the partition table from
.Pa da0 :
.Bd -literal -offset indent
/sbin/gpart backup da0 > da0.backup
.Ed
.Pp
Restore the partition table from the backup to
.Pa da0 :
.Bd -literal -offset indent
/sbin/gpart restore -l da0 < /mnt/da0.backup
.Ed
.Pp
Clone the partition table from
.Pa ada0
to
.Pa ada1
and
.Pa ada2 :
.Bd -literal -offset indent
/sbin/gpart backup ada0 | /sbin/gpart restore -F ada1 ada2
.Ed
.Sh SEE ALSO
.Xr geom 4 ,
.Xr boot0cfg 8 ,
.Xr geom 8 ,
.Xr gptboot 8
.Sh HISTORY
The
.Nm
utility appeared in
.Fx 7.0 .
.Sh AUTHORS
.An Marcel Moolenaar Aq Mt marcel@FreeBSD.org