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GPART(8)                FreeBSD System Manager's Manual               GPART(8)

NAME
     gpart - control utility for the disk partitioning GEOM class

SYNOPSIS
     To add support for the disk partitioning GEOM class, place one or more of
     the following lines in your kernel configuration file:

           options GEOM_PART_APM
           options GEOM_PART_BSD
           options GEOM_PART_EBR
           options GEOM_PART_GPT
           options GEOM_PART_MBR
           options GEOM_PART_PC98
           options GEOM_PART_VTOC8

     The GEOM_PART_APM option adds support for the Apple Partition Map (APM)
     found on Apple Macintosh computers.  The GEOM_PART_BSD option adds
     support for the traditional BSD disklabel.  The GEOM_PART_EBR option adds
     support for the Extended Boot Record (EBR), which is used to define a
     logical partition.  The GEOM_PART_GPT option adds support for the GUID
     Partition Table (GPT) found on Intel Itanium computers and Intel-based
     Macintosh computers.  The GEOM_PART_MBR option adds support for the
     Master Boot Record (MBR) found on PCs and used on many removable media.
     The GEOM_PART_PC98 option adds support for the MBR variant as used on NEC
     PC-98 computers.  The GEOM_PART_VTOC8 option adds support for Sun's SMI
     VTOC8 label as found on computers based on SPARC64 and UltraSPARC.

     Usage of the gpart utility:

     gpart add -t type [-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 [-s size] [-f flags] geom
     gpart restore [-lF] [-f flags] provider [...]
     gpart set -a attrib -i index [-f flags] geom
     gpart show [-lr] [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 of which 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 ommitted. 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:

                   -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 special format
                   used by 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.
                   For the GPT scheme, embedded bootstrap code is supported.
                   The bootstrap code is embedded in the protective MBR rather
                   than the GPT.  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.  For the
                   MBR scheme, it is a 512 byte file of which the first 446
                   bytes are installed as bootstrap code.  The -p partcode
                   option specifies a file that contains the bootstrap code
                   intended to be written to a partition.  For the VTOC8
                   scheme, it is a 8192 byte file of which the last 7680 bytes
                   are installed as bootstrap code.  The partition is
                   specified by the -i index option.  For the VTOC8 scheme, if
                   the -i index option is omitted, the bootstrap code is
                   written to all sufficiently large partitions.  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
                   being committed by default and will not result in pending
                   changes.  Actions can be modified with the -f flags option
                   so that they are not being committed by default.  As such,
                   they 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 any and 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 needs to 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 a
                               maximum number of entries and this option
                               allows tables to be created with the number of
                               entries that lies anywhere between the minimum
                               and the maximum.  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 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 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:

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

     restore       Restore the partition table from backup previously created
                   by backup action and given from standard input. Only
                   partition table may be restored. This action does not
                   affect content of partitions.  This mean that you should
                   copy your data from backup after restoring partition table
                   and write bootcode again if it is needed.

                   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 the current partition information of the specified
                   geoms or all geoms if none are specified.  Additional
                   options include:

                   -l          For partition schemes that support partition
                               labels print them instead of partition type.

                   -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.

PARTITION TYPES
     The gpart utility uses symbolic names for common partition types to avoid
     that the user needs to know what the partitioning scheme in question is
     and what the actual number or identification needs to be used for a
     particular type.  The gpart utility also allows the user to specify
     scheme-specific partition types for partition types that do not have
     symbol names.  The symbolic names currently understood are:

     efi                The system partition for computers that use the
                        Extensible Firmware Interface (EFI).  In such cases,
                        the GPT partitioning scheme is being used and the
                        actual partition type for the system partition can
                        also be specified as
                        "!c12a7328-f81f-11d2-ba4b-00a0c93ec93ab".

     freebsd            A FreeBSD partition that uses the BSD disklabel to
                        sub-divide the partition into file systems.  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 file
                        system.  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.

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
                     might be marked with the bootme attribute.  In such
                     scenario the gptboot will try all bootme partitions one
                     by one, until the next boot stage is successfully
                     entered.

     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.  Partitions with both bootonce and bootme
                     attributes are tried before partitions with only the
                     bootme attribute.  Before bootonce partition is tried,
                     the gptboot removes the bootme attribute and tries to
                     execute the next boot stage.  If it fails, the bootonce
                     attribute that is now alone is replaced with the
                     bootfailed attribute.  If the execution of the next boot
                     stage succeeds, but the system is not fully booted, the
                     gptboot will look for bootonce attributes alone (without
                     the bootme attribute) on the next system boot and will
                     replace those with the bootfailed attribute.  If the
                     system is fully booted, the /etc/rc.d/gptboot start-up
                     script will look for partition with the bootonce
                     attribute alone, will remove the attribute and log that
                     the system was successfully booted from this partition.
                     There should be at most one bootonce partition when
                     system is successfully booted.  Multiple partitions might
                     be marked with the bootonce and bootme attribute pairs.

     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.  This attribute is
                     used to mark partitions that had the bootonce attribute
                     set, but we failed to boot from them.  Once we
                     successfully boot, the /etc/rc.d/gptboot script will log
                     all the partitions we failed to boot from and will remove
                     the bootfailed attributes.

     The scheme-specific attributes for MBR:

     active

     The scheme-specific attributes for PC98:

     active

     bootable

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 class PART supports recovering of partition tables only for GPT.
     The GUID partition table has a primary and secondary (backup) copy of
     metadata for redundance. They are stored in the begining and in the end
     of device respectively. Therefore it is acceptable to have some
     corruptions in the metadata that are not fatal to work with GPT. When
     kernel detects corrupt metadata it marks this table as corrupt and
     reports about corruption.  Any changes in corrupt table are prohibited
     except destroy and recover.

     In case when only first sector is corrupt kernel can not detect GPT even
     if partition table is not corrupt. You can write protective MBR with
     dd(1) command to restore ability of GPT detection. The copy of protective
     MBR is usually located in the /boot/pmbr file.

     In case when some of metadata is corrupt you will get to know about this
     from kernel's messages like these:

           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 like show, status and list will report about corrupt
     table.

     In case when the size of device has changed (e.g. volume expansion) the
     secondary GPT header will become located not in the last sector. This is
     not a metadata corruption, but it is dangerous because any corruption of
     the primary GPT will lead to lost of partition table. Kernel reports
     about this problem with message:

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

     A corrupt table can be recovered with gpart recover command. This command
     does reconstruction of corrupt metadata using known valid metadata. Also
     it can relocate secondary GPT to the end of device.

     NOTE: The GEOM class PART can detect the same partition table on
     different GEOM providers and some of them will marked as corrupt. Be
     careful when choising a provider for recovering. If you did incorrect
     choise you can destroy metadata of another GEOM class, e.g. GEOM MIRROR
     or GEOM LABEL.

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

EXAMPLES
     Create GPT scheme on ad0.

           /sbin/gpart create -s GPT ad0

     Embed GPT bootstrap code into protective MBR.

           /sbin/gpart bootcode -b /boot/pmbr ad0

     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 /boot/gptboot, or the GPT boot you are
     planning to write, but smaller than 545 KB.  A size of 15 blocks (7680
     bytes) would be sufficient for booting from UFS but let's use 128 blocks
     (64 KB) here in this example, in order to reserve some space for
     potential future need (e.g. from a ZFS partition).

           /sbin/gpart add -b 34 -s 128 -t freebsd-boot ad0
           /sbin/gpart bootcode -p /boot/gptboot -i 1 ad0

     Create a 512MB-sized freebsd-ufs partition that would contain UFS where
     the system boots from.

           /sbin/gpart add -b 162 -s 1048576 -t freebsd-ufs ad0

     Create VTOC8 scheme on da0.

           /sbin/gpart create -s VTOC8 da0

     Create a 512MB-sized freebsd-ufs partition that would contain UFS where
     the system boots from.

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

     After having created all required partitions, embed bootstrap code into
     them.

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

     Create backup of partition table from da0

           /sbin/gpart backup da0 > da0.backup

     Restore partition table from backup to da0

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

     Clone partition table from ada0 to ada1 and ada2

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

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

HISTORY
     The gpart utility appeared in FreeBSD 7.0.

AUTHORS
     Marcel Moolenaar <marcel@FreeBSD.org>

FreeBSD 11.0-PRERELEASE        November 22, 2010       FreeBSD 11.0-PRERELEASE

NAME | SYNOPSIS | DESCRIPTION | PARTITION TYPES | ATTRIBUTES | OPERATIONAL FLAGS | RECOVERING | EXIT STATUS | EXAMPLES | SEE ALSO | HISTORY | AUTHORS

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