Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
GPART(8)                FreeBSD System Manager's Manual               GPART(8)

NAME
     gpart - control utility for the disk partitioning GEOM class

SYNOPSIS
     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

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
                   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 -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
                               entitled 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
                               entitled OPERATIONAL FLAGS below for a
                               discussion about its use.

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.

     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 are:

     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.

     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-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.

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.

     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 freebsd-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 the first sector of a provider is corrupt, the kernel can not detect
     GPT even if the partition table itself is not corrupt.  The protective
     MBR can be rewritten using the dd(1) command, to restore the ability to
     detect the GPT.  The copy of the protective MBR is usually located in the
     /boot/pmbr file.

     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.

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

EXAMPLES
     Create a GPT scheme on ada0:

           /sbin/gpart create -s GPT ada0

     Embed GPT bootstrap code into a protective MBR:

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

     Create a dedicated freebsd-boot partition that can boot FreeBSD from a
     freebsd-ufs partition, and install bootstrap code into it.  This
     partition must be larger than the bootstrap code (usually either
     /boot/gptboot or /boot/gptzfsboot), 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.  This example
     uses 88 blocks (44 kB) so the next partition will be aligned on a 64 kB
     boundary without the need to specify an explicit offset or alignment.
     The boot partition itself is aligned on a 4 kB boundary.

           /sbin/gpart add -b 40 -s 88 -t freebsd-boot ada0
           /sbin/gpart bootcode -p /boot/gptboot -i 1 ada0

     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 ada0

     Create an MBR scheme on ada0, then create a 30GB-sized FreeBSD slice,
     mark it active and install the boot0 boot manager:

           /sbin/gpart create -s MBR ada0
           /sbin/gpart add -t freebsd -s 30G ada0
           /sbin/gpart set -a active -i 1 ada0
           /sbin/gpart bootcode -b /boot/boot0 ada0

     Now create a BSD scheme (BSD label) with space for up to 20 partitions:

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

     Create a 1GB-sized UFS partition and a 4GB-sized swap partition:

           /sbin/gpart add -t freebsd-ufs -s 1G ada0s1
           /sbin/gpart add -t freebsd-swap -s 4G ada0s1

     Install bootstrap code 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

     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

SEE ALSO
     dd(1), geom(4), boot0cfg(8), geom(8), gptboot(8)

HISTORY
     The gpart utility appeared in FreeBSD 7.0.

AUTHORS
     Marcel Moolenaar <marcel@FreeBSD.org>

FreeBSD 11.0-PRERELEASE          July 1, 2013          FreeBSD 11.0-PRERELEASE

NAME | SYNOPSIS | DESCRIPTION | PARTITIONING SCHEMES | PARTITION TYPES | ATTRIBUTES | BOOTSTRAPPING | OPERATIONAL FLAGS | RECOVERING | SYSCTL VARIABLES | EXIT STATUS | EXAMPLES | SEE ALSO | HISTORY | AUTHORS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=gpart&sektion=8&manpath=FreeBSD+10.0-RELEASE>

home | help