GPART(8) BSD System Manager's Manual (INtime Distributed RTOS only).

Name

gpart -- control utility for the disk partitioning GEOM class

Command line

gpart add -t type [-a alignment] [-b start] [-s size] [-i index] [-l label] [-f flags] geom

gpart backup geom

gpart bootcode [-b bootcode] [-p partcode -i index] [-f flags] geom

gpart commit geom

gpart create -s scheme [-n entries] [-f flags] provider

gpart delete -i index [-f flags] geom

gpart destroy [-F] [-f flags] geom

gpart modify -i index [-l label] [-t type] [-f flags] geom

gpart recover [-f flags] geom

gpart resize -i index [-a alignment] [-s size] [-f flags] geom

gpart restore [-lF] [-f flags] provider [...]

gpart set -a attrib -i index [-f flags] geom

gpart show [-l | -r] [-p] [geom ...]

gpart undo geom

gpart unset -a attrib -i index [-f flags] geom

gpart list gpart status

gpart load

gpart unload

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 begins on the logical block address given by the -b start option. Its size is given by the -s size option. SI unit suffixes are allowed. One or both -b and -s options can be omitted. If so they are automatically calculated. The type of the partition is given by the -t type option. Partition types are discussed below in the section entitled PARTITION TYPES.

Additional options include:

-a alignment

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

-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.

-f flags

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

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). 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 -b bootcode option specifies a file that contains the bootstrap code. The contents and size of the file are determined by the partitioning scheme. The -p partcode option specifies a file that contains the bootstrap code intended to be written to a partition. The partition is specified by the -i index option. The size of the file must be smaller than the size of the partition.

Additional options include:

-f flags

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

commit

Commit any pending changes for geom geom. All actions are com- mitted 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 -s scheme option determines the scheme to use. The kernel must have support for a particular scheme before that scheme can be used to partition a disk.

Additional options include:

-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.

-f flags

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

delete

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

Additional options include:

-f flags

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

destroy

Destroy the partitioning scheme as implemented by geom geom.

Additional options include:

-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. To change the type of a partition, specify the new type with the -t type option. To change the label of a partition, specify the new label with the -l label option. Not all partitioning schemes support labels and it is invalid to try to change a partition label in such cases.

Additional options include:

-f flags

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

recover

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

Additional options include:

-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. New partition size is expressed in logical block numbers and can be given by the -s size option. If -s option is omitted then new size is automatically calculated to maximum available from given geom geom.

Additional options include:

-a alignment

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

-f flags

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

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.

Additional options include:

-F

Destroy partition table on the given provider before doing restore.

-l

Restore partition labels for partitioning schemes that support them.

-f flags

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

set

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

Additional options include:

-f flags

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

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.

Additional options include:

-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.

Additional options include:

-f flags

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

list

See geom(8).

status

See geom(8).

load

See geom(8).

unload

See geom(8).

Partitioining 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.

PC98

An MBR variant for NEC PC-98 and compatible computers. Requires the GEOM_PART_PC98 kernel option.

VTOC8

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

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). In such cases, the GPT partitioning scheme is used and the actual partition type for the system partition can also be specified as "!c12a7328-f81f-11d2-ba4b-00a0c93ec93b".

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.

Another symbolic names that can be used with gpart utility are:

apple-core-storage

An Apple Mac OS X partition used by logical volume manager known as Core Storage. The scheme-spe- cific 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.

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.

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 equiva- lent to partition types fat16, fat32 and ntfs in MBR. 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 "!0x9e1a2d38-c612-4316-aa26-8b49521e5a8b" 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 us- ing EFI.

The scheme-specific attributes for MBR:

active

The scheme-specific attributes for PC98:

active

bootable

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/zfsloader is started from the first one found.

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.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.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 au- tomatically recalculate the user-specified offset and size for alignment with the CHS geometry. Otherwise the values will be left unchanged.

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.

GPT

In this example, we will format ada0 with the GPT scheme and create boot, swap and root partitions. First, we need to create the partition table:

/bin/gpart create -s GPT ada0

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.

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

We then create a dedicated freebsd-boot partition to hold the second-stage boot loader, which will load the FreeBSD kernel and modules from a UFS or ZFS filesystem. This partition must be larger than the bootstrap code (either /boot/gptboot for UFS or /boot/gptzfsboot for ZFS), 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.

/bin/gpart add -b 40 -s 472 -t freebsd-boot ada0

/bin/gpart bootcode -p /boot/gptboot -i 1 ada0

We now create a 4 GB swap partition at the first available offset, which is 40 + 472 = 512 blocks (256 kB).

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

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 "advanced format" disks with 4096-byte physical blocks, to RAID volumes with stripe sizes of up to 256 kB.

Finally, we create and format an 8 GB freebsd-ufs partition for the root filesystem, leaving the rest of the slice free for additional filesystems:

/bin/gpart add -s 8G -t freebsd-ufs ada0

/bin/newfs -Uj /dev/ada0p3

MBR

In this example, we will format ada0 with the MBR scheme and create a single partition which we subdivide using a traditional BSD disklabel.

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:

/bin/gpart create -s MBR ada0

/bin/gpart add -t freebsd -s 64G ada0

/bin/gpart set -a active -i 1 ada0

/bin/gpart bootcode -b /boot/boot0 ada0

Next, we create a disklabel in that partition ("slice" in disklabel terminology) with room for up to 20 partitions:

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

We then create an 8 GB root partition and a 4 GB swap partition:

/bin/gpart add -t freebsd-ufs -s 8G ada0s1

/bin/gpart add -t freebsd-swap -s 4G ada0s1

Finally, we install the appropriate boot loader for the BSD label:

/bin/gpart bootcode -b /boot/boot ada0s1

VTOC8

Create a VTOC8 scheme on da0:

/bin/gpart create -s VTOC8 da0

Create a 512MB-sized freebsd-ufs partition to contain a UFS filesystem from which the system can boot.

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

Create a 15GB-sized freebsd-ufs partition to contain a UFS filesystem and aligned on 4KB boundaries:

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

After creating all required partitions, embed bootstrap code into them:

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

Backup and Restore

Create a backup of the partition table from da0:

/bin/gpart backup da0 > da0.backup

Restore the partition table from the backup to da0:

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

Clone the partition table from ada0 to ada1 and ada2:

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

History

The gpart utility appeared in FreeBSD 7.0.

Authors

Marcel Moolenaar <marcel@FreeBSD.org>