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GPART(8)		  BSD 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 sup‐
     port 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 Mas‐
     ter 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 repre‐
			   sent 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 partition‐
	       ing 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 boot‐
	       strap 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 speci‐
	       fied 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 maxi‐
			   mum 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 con‐
			   sidered 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 parti‐
	       tion can be modified.  To change the type of a partition, spec‐
	       ify 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 ta‐
	       ble 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 sec‐
	       tion 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 sec‐
	       tion 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 par‐
     ticular 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 parti‐
		    tioning 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 sys‐
		    tem.  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.	Parti‐
		 tions 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 par‐
		 titions 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 corrup‐
     tions 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 differ‐
     ent 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 parti‐
     tion 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⟩

BSD			       November 22, 2010			   BSD
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