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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 rep-
			     resent 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 partition-
	       ing 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 com-
	       mitted 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 num-
			   ber 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 par-
	       tition table is restored.  This action does not affect the con-
	       tent 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	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 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 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.

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 parti-
	    tions.  (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-spe-
		      cific type is "!21686148-6449-6E6F-744E-656564454649".

     efi	      The system partition for computers that use the Extensi-
		      ble 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 filesys-
		      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.

     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.	Multi-
		 ple 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	dif-
     ferent 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	embed-
     ded 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,	embed-
     ded 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	boot-
     strap 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 Ta-
     ble.  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 parti-
     tion: /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 cor-
     rupt tables.

     If	the size of the	device has changed (e.g., volume expansion) the	sec-
     ondary 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 relo-
     cates 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 cor-
     rupt.  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	mini-
	     mal 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 sec-
	     tion).  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 parti-
     tion 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	10.1			 July 1, 2013			  FreeBSD 10.1

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

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