gpart
—
control utility for the disk partitioning GEOM
class
gpart |
add
-t
type
[-a
alignment ]
[-b
start ]
[-s
size ]
[-i
index ]
[-l
label ]
[-f
flags ]
geom |
gpart |
bootcode
[-b
bootcode ]
[-p
partcode
-i
index ]
[-f
flags ]
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 |
unset
-a
attrib
-i
index
[-f
flags ]
geom |
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
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:
-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 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
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).
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.
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.
Another symbolic names that can be used with
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.
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.
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. 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.
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
-
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.
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.
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.
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.auto_resize:
1
- This variable controls automatic resize behavior of
gpart
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.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.
Exit status is 0 on success, and 1 if the command fails.
The examples below assume that the disk's logical block size is 512 bytes,
regardless of its physical block size.
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:
/sbin/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.
/sbin/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.
/sbin/gpart add -b 40 -s 472 -t freebsd-boot ada0
/sbin/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).
/sbin/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:
/sbin/gpart add -s 8G -t freebsd-ufs ada0
/sbin/newfs -Uj /dev/ada0p3
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:
/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
Next, we create a disklabel in that partition (“slice” in
disklabel terminology) with room for up to 20 partitions:
/sbin/gpart create -s BSD -n 20 ada0s1
We then create an 8 GB root partition and a 4 GB swap partition:
/sbin/gpart add -t freebsd-ufs -s 8G ada0s1
/sbin/gpart add -t freebsd-swap -s 4G ada0s1
Finally, we install the appropriate boot loader for the
BSD label:
/sbin/gpart bootcode -b /boot/boot ada0s1
Create a VTOC8 scheme on
da0:
/sbin/gpart create -s VTOC8 da0
Create a 512MB-sized
freebsd-ufs
partition to
contain a UFS filesystem from which the system can boot.
/sbin/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:
/sbin/gpart add -s 15G -t freebsd-ufs -a 4k da0
After creating all required partitions, embed bootstrap code into them:
/sbin/gpart bootcode -p /boot/boot1 da0
If a
Device busy error is shown when trying to
destroy a partition table, remember that all of the partitions must be deleted
first with the
delete
action. In this
example,
da0 has three partitions:
/sbin/gpart delete -i 3 da0
/sbin/gpart delete -i 2 da0
/sbin/gpart delete -i 1 da0
/sbin/gpart destroy da0
Rather than deleting each partition and then destroying the partitioning scheme,
the
-F
option can be given with
destroy
to delete all of the partitions
before destroying the partitioning scheme. This is equivalent to the previous
example:
/sbin/gpart destroy -F da0
Create a backup of the partition table from
da0:
/sbin/gpart backup da0 > da0.backup
Restore the partition table from the backup to
da0:
/sbin/gpart restore -l da0 < /mnt/da0.backup
Clone the partition table from
ada0 to
ada1 and
ada2:
/sbin/gpart backup ada0 | /sbin/gpart restore -F ada1 ada2
geom(4),
boot0cfg(8),
geom(8),
gptboot(8)
The
gpart
utility appeared in
FreeBSD 7.0.
Marcel Moolenaar
<
marcel@FreeBSD.org>