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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	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>

FreeBSD	10.1		       November	22, 2010		  FreeBSD 10.1

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

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