Руководство по gpart

NAME

gpart —

control utility for the disk partitioning GEOM class

SYNOPSIS

DESCRIPTION

The gpart utility is used to partition GEOM providers,
normally disks. The first argument is the action to be taken:

add

Add a new partition to the partitioning scheme given by
geom. The partition type must be specified with
-t type. The partition’s
location, size, and other attributes will be calculated automatically if
the corresponding options are not specified.

The add command accepts these
options:

-a
alignment

If specified, then the gpart utility tries to
align start offset and partition
size to be multiple of
alignment value.

-b
start

The logical block address where the partition will begin. A SI unit
suffix is allowed.

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-i
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.

-l
label

The label attached to the partition. This option is only valid when
used on partitioning schemes that support partition labels.

-s
size

Create a partition of size size. A SI unit
suffix is allowed.

-t
type

Create a partition of type type. Partition types
are discussed below in the section entitled
PARTITION TYPES.

backup

Dump a partition table to standard output in a special format used by the
restore action.

bootcode

Embed bootstrap code into the partitioning scheme’s metadata on the
geom (using -b
bootcode) or write bootstrap code into a partition
(using -p partcode and
-i index).

The bootcode command accepts these
options:

-N

Do not preserve the Volume Serial Number for MBR. MBR bootcode
contains Volume Serial Number by default, and
gpart tries to preserve it when installing new
bootstrap code. This option skips preservation to help with some
versions of
boot0(8)
that do not support Volume Serial Number.

-b
bootcode

Embed bootstrap code from the file bootcode into
the partitioning scheme’s metadata for geom. Not
all partitioning schemes have embedded bootstrap code, so the
-b bootcode option is
scheme-specific in nature (see the section entitled
BOOTSTRAPPING below). The
bootcode file must match the partitioning
scheme’s requirements for file content and size.

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-i
index

Specify the target partition for -p
partcode.

-p
partcode

Write the bootstrap code from the file partcode
into the geom partition specified by
-i index. The size of
the file must be smaller than the size of the partition.

commit

Commit any pending changes for geom geom. All
actions are committed by default and will not result in pending changes.
Actions can be modified with the -f
flags option so that they are not committed, but
become pending. Pending changes are reflected by the geom and the
gpart utility, but they are not actually written
to disk. The commit action will write all pending
changes to disk.

create

Create a new partitioning scheme on a provider given by
provider. The scheme to use must be specified with
the -s scheme option.

The create command accepts these
options:

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-n
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.

-s
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.

delete

Delete a partition from geom geom and further
identified by the -i index
option. The partition cannot be actively used by the kernel.

The delete command accepts these
options:

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-i
index

Specifies the index of the partition to be deleted.

destroy

Destroy the partitioning scheme as implemented by geom
geom.

The destroy command accepts these
options:

-F

Forced destroying of the partition table even if it is not empty.

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

modify

Modify a partition from geom geom and further
identified by the -i 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.

The modify command accepts these
options:

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-i
index

Specifies the index of the partition to be modified.

-l
label

Change the partition label to label.

-t
type

Change the partition type to type.

recover

Recover a corrupt partition’s scheme metadata on the geom
geom. See the section entitled
RECOVERING below for the additional
information.

The recover command accepts these
options:

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

resize

Resize a partition from geom geom and further
identified by the -i index
option. If the new size is not specified it is automatically calculated to
be the maximum available from geom.

The resize command accepts these
options:

-a
alignment

If specified, then the gpart utility tries to
align partition size to be a multiple of the
alignment value.

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-i
index

Specifies the index of the partition to be resized.

-s
size

Specifies the new size of the partition, in logical blocks. A SI unit
suffix is allowed.

restore

Restore the partition table from a backup previously created by the
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.

The restore command accepts these
options:

-F

Destroy partition table on the given provider
before doing restore.

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-l

Restore partition labels for partitioning schemes that support
them.

set

Set the named attribute on the partition entry. See the section entitled
ATTRIBUTES below for a list of
available attributes.

The set command accepts these
options:

-a
attrib

Specifies the attribute to set.

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-i
index

Specifies the index of the partition on which the attribute will be
set.

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
gpart list.

The show command accepts these
options:

-l

For partitioning schemes that support partition labels, print them
instead of partition type.

-p

Show provider names instead of partition indexes.

-r

Show raw partition type instead of symbolic name.

undo

Revert any pending changes for geom geom. This
action is the opposite of the commit action and
can be used to undo any changes that have not been committed.

unset

Clear the named attribute on the partition entry. See the section entitled
ATTRIBUTES below for a list of
available attributes.

The unset command accepts these
options:

-a
attrib

Specifies the attribute to clear.

-f
flags

Additional operational flags. See the section entitled
OPERATIONAL FLAGS below
for a discussion about its use.

-i
index

Specifies the index of the partition on which the attribute will be
cleared.

list

See
geom(8).

status

See
geom(8).

load

See
geom(8).

unload

See
geom(8).

PARTITIONING
SCHEMES

Several partitioning schemes are supported by the gpart
utility:

APM

Apple Partition Map, used by PowerPC(R) Macintosh(R) computers. Requires
the GEOM_PART_APM kernel option.

BSD

Traditional BSD disklabel, usually used to subdivide MBR partitions. (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 “dangerously dedicated”.) Requires the
GEOM_PART_BSD kernel option.

BSD64

64-bit implementation of BSD disklabel used in DragonFlyBSD to subdivide
MBR or GPT partitions. Requires the
GEOM_PART_BSD64 kernel option.

LDM

The Logical Disk Manager is an implementation of volume manager for
Microsoft Windows NT. Requires the GEOM_PART_LDM
kernel option.

GPT

GUID Partition Table is used on Intel-based Macintosh computers and
gradually replacing MBR on most PCs and other systems. Requires the
GEOM_PART_GPT kernel option.

MBR

Master Boot Record is used on PCs and removable media. Requires the
GEOM_PART_MBR kernel option. The
GEOM_PART_EBR option adds support for the Extended
Boot Record (EBR), which is used to define a logical partition. The
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.

VTOC8

Sun’s SMI Volume Table Of Contents, used by SPARC64 and UltraSPARC
computers. Requires the GEOM_PART_VTOC8 kernel
option.

See
glabel(8)
for additional information on labelization of devices and partitions.

PARTITION
TYPES

Partition types are identified on disk by particular strings or magic values.
The gpart 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
gpart 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
FreeBSD are:

apple-boot

The system partition dedicated to storing boot loaders on some Apple
systems. The scheme-specific types are
“!171” for MBR,
“!Apple_Bootstrap” for APM, and
“!426f6f74-0000-11aa-aa11-00306543ecac”
for GPT.

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
“!21686148-6449-6E6F-744E-656564454649”.

efi

The system partition for computers that use the Extensible Firmware
Interface (EFI). The scheme-specific types are
“!239” for MBR, and
“!c12a7328-f81f-11d2-ba4b-00a0c93ec93b”
for GPT.

freebsd

A FreeBSD partition subdivided into filesystems
with a BSD disklabel. This is a legacy partition
type and should not be used for the APM or GPT schemes. The
scheme-specific types are “!165” for
MBR, “!FreeBSD” for APM, and
“!516e7cb4-6ecf-11d6-8ff8-00022d09712b”
for GPT.

freebsd-boot

A FreeBSD partition dedicated to bootstrap code.
The scheme-specific type is
“!83bd6b9d-7f41-11dc-be0b-001560b84f0f”
for GPT.

freebsd-swap

A FreeBSD partition dedicated to swap space. The
scheme-specific types are
“!FreeBSD-swap” for APM,
“!516e7cb5-6ecf-11d6-8ff8-00022d09712b”
for GPT, and tag 0x0901 for VTOC8.

freebsd-ufs

A FreeBSD partition that contains a UFS or UFS2
filesystem. The scheme-specific types are
“!FreeBSD-UFS” for APM,
“!516e7cb6-6ecf-11d6-8ff8-00022d09712b”
for GPT, and tag 0x0902 for VTOC8.

freebsd-vinum

A FreeBSD partition that contains a Vinum volume.
The scheme-specific types are
“!FreeBSD-Vinum” for APM,
“!516e7cb8-6ecf-11d6-8ff8-00022d09712b”
for GPT, and tag 0x0903 for VTOC8.

freebsd-zfs

A FreeBSD partition that contains a ZFS volume.
The scheme-specific types are
“!FreeBSD-ZFS” for APM,
“!516e7cba-6ecf-11d6-8ff8-00022d09712b”
for GPT, and 0x0904 for VTOC8.

Other symbolic names that can be used with the
gpart utility are:

apple-apfs

An Apple macOS partition used for the Apple file system, APFS.

apple-core-storage

An Apple Mac OS X partition used by logical volume manager known as Core
Storage. The scheme-specific type is
“!53746f72-6167-11aa-aa11-00306543ecac”
for GPT.

apple-hfs

An Apple Mac OS X partition that contains a HFS or HFS+ filesystem. The
scheme-specific types are “!175” for
MBR, “!Apple_HFS” for APM and
“!48465300-0000-11aa-aa11-00306543ecac”
for GPT.

apple-label

An Apple Mac OS X partition dedicated to partition metadata that descibes
disk device. The scheme-specific type is
“!4c616265-6c00-11aa-aa11-00306543ecac”
for GPT.

apple-raid

An Apple Mac OS X partition used in a software RAID configuration. The
scheme-specific type is
“!52414944-0000-11aa-aa11-00306543ecac”
for GPT.

apple-raid-offline

An Apple Mac OS X partition used in a software RAID configuration. The
scheme-specific type is
“!52414944-5f4f-11aa-aa11-00306543ecac”
for GPT.

apple-tv-recovery

An Apple Mac OS X partition used by Apple TV. The scheme-specific type is
“!5265636f-7665-11aa-aa11-00306543ecac”
for GPT.

apple-ufs

An Apple Mac OS X partition that contains a UFS filesystem. The
scheme-specific types are “!168” for
MBR, “!Apple_UNIX_SVR2” for APM and
“!55465300-0000-11aa-aa11-00306543ecac”
for GPT.

apple-zfs

An Apple Mac OS X partition that contains a ZFS volume. The
scheme-specific type is
“!6a898cc3-1dd2-11b2-99a6-080020736631”
for GPT. The same GUID is being used also for
illumos/Solaris /usr partition. See
CAVEATS section below.

dragonfly-label32

A DragonFlyBSD partition subdivided into filesystems with a
BSD disklabel. The scheme-specific type is
“!9d087404-1ca5-11dc-8817-01301bb8a9f5”
for GPT.

dragonfly-label64

A DragonFlyBSD partition subdivided into filesystems with a disklabel64.
The scheme-specific type is
“!3d48ce54-1d16-11dc-8696-01301bb8a9f5”
for GPT.

dragonfly-legacy

A legacy partition type used in DragonFlyBSD. The scheme-specific type is
“!bd215ab2-1d16-11dc-8696-01301bb8a9f5”
for GPT.

dragonfly-ccd

A DragonFlyBSD partition used with Concatenated Disk driver. The
scheme-specific type is
“!dbd5211b-1ca5-11dc-8817-01301bb8a9f5”
for GPT.

dragonfly-hammer

A DragonFlyBSD partition that contains a Hammer filesystem. The
scheme-specific type is
“!61dc63ac-6e38-11dc-8513-01301bb8a9f5”
for GPT.

dragonfly-hammer2

A DragonFlyBSD partition that contains a Hammer2 filesystem. The
scheme-specific type is
“!5cbb9ad1-862d-11dc-a94d-01301bb8a9f5”
for GPT.

dragonfly-swap

A DragonFlyBSD partition dedicated to swap space. The scheme-specific type
is
“!9d58fdbd-1ca5-11dc-8817-01301bb8a9f5”
for GPT.

dragonfly-ufs

A DragonFlyBSD partition that contains an UFS1 filesystem. The
scheme-specific type is
“!9d94ce7c-1ca5-11dc-8817-01301bb8a9f5”
for GPT.

dragonfly-vinum

A DragonFlyBSD partition used with Logical Volume Manager. The
scheme-specific type is
“!9dd4478f-1ca5-11dc-8817-01301bb8a9f5”
for GPT.

ebr

A partition subdivided into filesystems with a EBR. The scheme-specific
type is “!5” for MBR.

fat16

A partition that contains a FAT16 filesystem. The scheme-specific type is
“!6” for MBR.

fat32

A partition that contains a FAT32 filesystem. The scheme-specific type is
“!11” for MBR.

fat32lba

A partition that contains a FAT32 (LBA) filesystem. The scheme-specific
type is “!12” for MBR.

hifive-fsbl

A raw partition containing a HiFive first stage bootloader. The
scheme-specific type is
“!5b193300-fc78-40cd-8002-e86c45580b47”
for GPT.

hifive-bbl

A raw partition containing a HiFive second stage bootloader. The
scheme-specific type is
“!2e54b353-1271-4842-806f-e436d6af6985”
for GPT.

linux-data

A Linux partition that contains some filesystem with data. The
scheme-specific types are “!131” for
MBR and
“!0fc63daf-8483-4772-8e79-3d69d8477de4”
for GPT.

linux-lvm

A Linux partition dedicated to Logical Volume Manager. The scheme-specific
types are “!142” for MBR and
“!e6d6d379-f507-44c2-a23c-238f2a3df928”
for GPT.

linux-raid

A Linux partition used in a software RAID configuration. The
scheme-specific types are “!253” for
MBR and
“!a19d880f-05fc-4d3b-a006-743f0f84911e”
for GPT.

linux-swap

A Linux partition dedicated to swap space. The scheme-specific types are
“!130” for MBR and
“!0657fd6d-a4ab-43c4-84e5-0933c84b4f4f”
for GPT.

mbr

A partition that is sub-partitioned by a Master Boot Record (MBR). This
type is known as
“!024dee41-33e7-11d3-9d69-0008c781f39f”
by GPT.

ms-basic-data

A basic data partition (BDP) for Microsoft operating systems. In the GPT
this type is the equivalent to partition types
fat16, fat32 and
ntfs in MBR. This type is used for GPT exFAT
partitions. The scheme-specific type is
“!ebd0a0a2-b9e5-4433-87c0-68b6b72699c7”
for GPT.

ms-ldm-data

A partition that contains Logical Disk Manager (LDM) volumes. The
scheme-specific types are “!66” for
MBR,
“!af9b60a0-1431-4f62-bc68-3311714a69ad”
for GPT.

ms-ldm-metadata

A partition that contains Logical Disk Manager (LDM) database. The
scheme-specific type is
“!5808c8aa-7e8f-42e0-85d2-e1e90434cfb3”
for GPT.

netbsd-ccd

A NetBSD partition used with Concatenated Disk driver. The scheme-specific
type is
“!2db519c4-b10f-11dc-b99b-0019d1879648”
for GPT.

netbsd-cgd

An encrypted NetBSD partition. The scheme-specific type is
“!2db519ec-b10f-11dc-b99b-0019d1879648”
for GPT.

netbsd-ffs

A NetBSD partition that contains an UFS filesystem. The scheme-specific
type is
“!49f48d5a-b10e-11dc-b99b-0019d1879648”
for GPT.

netbsd-lfs

A NetBSD partition that contains an LFS filesystem. The scheme-specific
type is
“!49f48d82-b10e-11dc-b99b-0019d1879648”
for GPT.

netbsd-raid

A NetBSD partition used in a software RAID configuration. The
scheme-specific type is
“!49f48daa-b10e-11dc-b99b-0019d1879648”
for GPT.

netbsd-swap

A NetBSD partition dedicated to swap space. The scheme-specific type is
“!49f48d32-b10e-11dc-b99b-0019d1879648”
for GPT.

ntfs

A partition that contains a NTFS or exFAT filesystem. The scheme-specific
type is “!7” for MBR.

prep-boot

The system partition dedicated to storing boot loaders on some PowerPC
systems, notably those made by IBM. The scheme-specific types are
“!65” for MBR and
“!9e1a2d38-c612-4316-aa26-8b49521e5a8b”
for GPT.

solaris-boot

A illumos/Solaris partition dedicated to boot loader. The scheme-specific
type is
“!6a82cb45-1dd2-11b2-99a6-080020736631”
for GPT.

solaris-root

A illumos/Solaris partition dedicated to root filesystem. The
scheme-specific type is
“!6a85cf4d-1dd2-11b2-99a6-080020736631”
for GPT.

solaris-swap

A illumos/Solaris partition dedicated to swap. The scheme-specific type is
“!6a87c46f-1dd2-11b2-99a6-080020736631”
for GPT.

solaris-backup

A illumos/Solaris partition dedicated to backup. The scheme-specific type
is
“!6a8b642b-1dd2-11b2-99a6-080020736631”
for GPT.

solaris-var

A illumos/Solaris partition dedicated to /var filesystem. The
scheme-specific type is
“!6a8ef2e9-1dd2-11b2-99a6-080020736631”
for GPT.

solaris-home

A illumos/Solaris partition dedicated to /home filesystem. The
scheme-specific type is
“!6a90ba39-1dd2-11b2-99a6-080020736631”
for GPT.

solaris-altsec

A illumos/Solaris partition dedicated to alternate sector. The
scheme-specific type is
“!6a9283a5-1dd2-11b2-99a6-080020736631”
for GPT.

solaris-reserved

A illumos/Solaris partition dedicated to reserved space. The
scheme-specific type is
“!6a945a3b-1dd2-11b2-99a6-080020736631”
for GPT.

vmware-vmfs

A partition that contains a VMware File System (VMFS). The scheme-specific
types are “!251” for MBR and
“!aa31e02a-400f-11db-9590-000c2911d1b8”
for GPT.

vmware-vmkdiag

A partition that contains a VMware diagostic filesystem. The
scheme-specific types are “!252” for
MBR and
“!9d275380-40ad-11db-bf97-000c2911d1b8”
for GPT.

vmware-reserved

A VMware reserved partition. The scheme-specific type is
“!9198effc-31c0-11db-8f-78-000c2911d1b8”
for GPT.

vmware-vsanhdr

A partition claimed by VMware VSAN. The scheme-specific type is
“!381cfccc-7288-11e0-92ee-000c2911d0b2”
for GPT.

ATTRIBUTES

The scheme-specific attributes for EBR:

active

 

The scheme-specific attributes for GPT:

bootme

When set, the gptboot stage 1 boot loader will try
to boot the system from this partition. Multiple partitions can be marked
with the bootme attribute. See
gptboot(8)
for more details.

bootonce

Setting this attribute automatically sets the
bootme attribute. When set, the
gptboot stage 1 boot loader will try to boot the
system from this partition only once. Multiple partitions can be marked
with the bootonce and
bootme attribute pairs. See
gptboot(8)
for more details.

bootfailed

This attribute should not be manually managed. It is managed by the
gptboot stage 1 boot loader and the
/etc/rc.d/gptboot start-up script. See
gptboot(8)
for more details.

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.

The scheme-specific attributes for MBR:

active

 

BOOTSTRAPPING

FreeBSD 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.

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 gpart bootcode command with the
-b bootcode option. The GEOM
PART class knows how to safely embed bootstrap code into specific
partitioning scheme metadata without causing any damage.

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: /boot/mbr and
/boot/boot0. /boot/mbr
searches for a partition with the active attribute
(see the ATTRIBUTES section) in the
partition table. Then it runs next bootstrap stage. The
/boot/boot0 image contains a boot manager with some
additional interactive functions for multi-booting from a user-selected
partition.

A BSD disklabel is usually created inside an MBR partition (slice)
with type freebsd (see the
PARTITION TYPES section). It uses
8 KB size bootstrap code image /boot/boot, embedded
into the partition table’s metadata area.

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 /boot/pmbr image. It searches
through the GPT for a freebsd-boot partition (see
the PARTITION TYPES section) and
runs the next bootstrap stage from it. The
freebsd-boot partition should be smaller than 545
KB. It can be located either before or after other
FreeBSD partitions on the disk. There are two
variants of bootstrap code to write to this partition:
/boot/gptboot and
/boot/gptzfsboot.

/boot/gptboot is used to boot from UFS
partitions. gptboot searches through
freebsd-ufs partitions in the GPT and selects one to
boot based on the bootonce and
bootme attributes. If neither attribute is found,
/boot/gptboot boots from the first
freebsd-ufs partition.
/boot/loader (the third bootstrap stage) is loaded
from the first partition that matches these conditions. See
gptboot(8)
for more information.

/boot/gptzfsboot is used to boot from ZFS.
It searches through the GPT for freebsd-zfs
partitions, trying to detect ZFS pools. After all pools are detected,
/boot/loader is started from the first one found set
as bootable.

The VTOC8 scheme does not support embedding bootstrap code.
Instead, the 8 KBytes bootstrap code image
/boot/boot1 should be written with the
gpart bootcode command with the
-p bootcode option to all
sufficiently large VTOC8 partitions. To do this the
-i index option could be
omitted.

The APM scheme also does not support embedding bootstrap code.
Instead, the 800 KBytes bootstrap code image
/boot/boot1.hfs should be written with the
gpart bootcode command to a partition of type
apple-boot, which should also be 800 KB in size.

OPERATIONAL
FLAGS

Actions other than the commit and
undo actions take an optional
-f flags option. This option is
used to specify action-specific operational flags. By default, the
gpart utility defines the
‘C’ flag so that the action is
immediately committed. The user can specify “-f
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 commit action or reverted
with the undo action.

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 (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. destroy and
recover are the only operations allowed on corrupt
tables.

If one GPT header appears to be corrupt but the other copy remains
intact, the kernel will log the following:

GEOM: provider: the primary GPT table is corrupt or invalid.
GEOM: provider: using the secondary instead -- recovery strongly advised.

or

GEOM: provider: the secondary GPT table is corrupt or invalid.
GEOM: provider: using the primary only -- recovery suggested.

Also gpart commands such as
show, status and
list will report about corrupt tables.

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:

GEOM: provider: the secondary GPT header is not in the last LBA.

This situation can be recovered with the
recover command. This command reconstructs the
corrupt metadata using known valid metadata and relocates the secondary GPT
to the end of the device.

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.

SYSCTL
VARIABLES

The following
sysctl(8)
variables can be used to control the behavior of the
PART GEOM class. The default value is shown next to
each variable.

kern.geom.part.allow_nesting:
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.

kern.geom.part.auto_resize:
1

This variable controls automatic resize behavior of the
PART 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 gpart commit
is run to confirm changes. This behavior is also reported with diagnostic
message: GEOM_PART: (provider) was automatically
resized. Use `gpart commit (provider)` to save changes
or `gpart undo (provider)` to revert them.

kern.geom.part.check_integrity:
1

This variable controls the behaviour of metadata integrity checks. When
integrity checks are enabled, the 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: GEOM_PART: Integrity check failed
(provider, scheme).

kern.geom.part.gpt.allow_nesting:
0

By default the GPT scheme is allowed only at the outermost nesting level.
This variable allows this restriction to be removed.

kern.geom.part.ldm.debug:
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.

kern.geom.part.ldm.show_mirrors:
0

This variable controls how the Logical Disk Manager (LDM) module handles
mirrored volumes. By default mirrored volumes are shown as partitions with
type ms-ldm-data (see the
PARTITION TYPES section). If
this variable set to 1 each component of the mirrored volume will be
present as independent partition. NOTE: This may break a
mirrored volume and lead to data damage.

kern.geom.part.mbr.enforce_chs:
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.

kern.geom.part.separator:

Specify an optional separator that will be inserted between the GEOM name
and partition name. This variable is a
loader(8)
tunable. Note that setting this variable may break software which assumes
a particular naming scheme.

EXIT
STATUS

Exit status is 0 on success, and 1 if the command fails.

EXAMPLES

The examples below assume that the disk’s logical block size is 512 bytes,
regardless of its physical block size.

/sbin/gpart create -s GPT ada0

/sbin/gpart bootcode -b /boot/pmbr ada0

/sbin/gpart add -b 40 -s 472 -t freebsd-boot ada0
/sbin/gpart bootcode -p /boot/gptboot -i 1 ada0

/sbin/gpart add -s 4G -t freebsd-swap ada0

/sbin/gpart add -s 8G -t freebsd-ufs ada0
/sbin/newfs -Uj /dev/ada0p3

/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

/sbin/gpart create -s BSD -n 20 ada0s1

/sbin/gpart add -t freebsd-ufs -s 8G ada0s1
/sbin/gpart add -t freebsd-swap -s 4G ada0s1

/sbin/gpart bootcode -b /boot/boot ada0s1

/sbin/gpart create -s VTOC8 da0

/sbin/gpart add -s 512M -t freebsd-ufs da0

/sbin/gpart add -s 15G -t freebsd-ufs -a 4k da0

/sbin/gpart bootcode -p /boot/boot1 da0

/sbin/gpart delete -i 3 da0
/sbin/gpart delete -i 2 da0
/sbin/gpart delete -i 1 da0
/sbin/gpart destroy da0

/sbin/gpart destroy -F da0

/sbin/gpart backup da0 > da0.backup

/sbin/gpart restore -l da0 < /mnt/da0.backup

/sbin/gpart backup ada0 | /sbin/gpart restore -F ada1 ada2

SEE
ALSO

geom(4),
boot0cfg(8),
geom(8),
glabel(8),
gptboot(8)

HISTORY

The gpart utility appeared in FreeBSD
7.0.

Marcel Moolenaar
<marcel@FreeBSD.org>

CAVEATS

Partition type apple-zfs
(6a898cc3-1dd2-11b2-99a6-080020736631) is also being used on illumos/Solaris
platforms for ZFS volumes.