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

FreeBSD Manual Pages

  
 
  

home | help
GDISK(8)		       GPT fdisk Manual			      GDISK(8)

NAME
       gdisk - Interactive GUID	partition table	(GPT) manipulator

SYNOPSIS
       gdisk [ -l ] device

DESCRIPTION
       GPT  fdisk  (aka	gdisk) is a text-mode menu-driven program for creation
       and manipulation	of partition tables. It	will automatically convert  an
       old-style  Master  Boot	Record	(MBR) partition	table or BSD disklabel
       stored without an MBR carrier partition to the  newer  Globally	Unique
       Identifier  (GUID)  Partition  Table  (GPT) format, or will load	a GUID
       partition table.	When used with the -l command-line option, the program
       displays	the current partition table and	then exits.

       GPT fdisk operates mainly on the	GPT headers and	partition tables; how-
       ever, it	can and	will generate a	fresh protective MBR,  when  required.
       (Any  boot loader code in the protective	MBR will not be	disturbed.) If
       you've created an unusual protective MBR, such as a hybrid MBR  created
       by  gptsync or gdisk's own hybrid MBR creation feature, this should not
       be disturbed by most ordinary actions. Some advanced data recovery  op-
       tions  require  you to understand the distinctions between the main and
       backup data, as well as between the GPT headers and the	partition  ta-
       bles.  For  information	on MBR vs. GPT,	as well	as GPT terminology and
       structure, see the extended  gdisk  documentation  at  http://www.rods-
       books.com/gdisk/	or consult Wikipedia.

       The  gdisk  program employs a user interface similar to that of Linux's
       fdisk, but gdisk	modifies GPT partitions. It also has the capability of
       transforming MBR	partitions or BSD disklabels into GPT partitions. Like
       the original fdisk program, gdisk does not modify disk structures until
       you  explicitly	write  them to disk, so	if you make a mistake, you can
       exit from the program with the 'q' option to leave your partitions  un-
       modified.

       Ordinarily,  gdisk  operates  on	disk device files, such	as /dev/sda or
       /dev/hda	under Linux,  /dev/disk0  under	 Mac  OS  X,  or  /dev/ad0  or
       /dev/da0	 under	FreeBSD.  The  program	can also operate on disk image
       files, which can	be either copies of whole disks	(made with dd, for in-
       stance)	or  raw	 disk images used by emulators such as QEMU or VMWare.
       Note that only raw disk images are supported; gdisk cannot work on com-
       pressed or other	advanced disk image formats.

       The  MBR	partitioning system uses a combination of cylinder/head/sector
       (CHS) addressing	and logical block  addressing  (LBA).  The  former  is
       klunky  and limiting. GPT drops CHS addressing and uses 64-bit LBA mode
       exclusively. Thus, GPT data structures, and  therefore  gdisk,  do  not
       need  to	 deal  with  CHS  geometries and all the problems they create.
       Users of	fdisk will note	that gdisk lacks the options  and  limitations
       associated with CHS geometries.

       For best	results, you should use	an OS-specific partition table program
       whenever	possible. For example, you should make	Mac  OS	 X  partitions
       with  the  Mac  OS X Disk Utility program and Linux partitions with the
       Linux gdisk or GNU Parted program.

       Upon start, gdisk attempts to identify the partition type in use	on the
       disk.  If  it finds valid GPT data, gdisk will use it. If gdisk finds a
       valid MBR or BSD	disklabel but no GPT data, it will attempt to  convert
       the  MBR	or disklabel into GPT form. (BSD disklabels are	likely to have
       unusable	first and/or final partitions because they  overlap  with  the
       GPT  data structures, though.) GPT fdisk	can identify, but not use data
       in, Apple Partition Map (APM) disks, which are used on 680x0- and  Pow-
       erPC-based  Macintoshes.	 Upon  exiting	with the 'w' option, gdisk re-
       places the MBR or disklabel with	a GPT. This action is potentially dan-
       gerous! Your system may become unbootable, and partition	type codes may
       become corrupted	if the disk uses unrecognized type codes.  Boot	 prob-
       lems  are  particularly likely if you're	multi-booting with any GPT-un-
       aware OS. If you	mistakenly launch gdisk	on an MBR disk,	you can	safely
       exit the	program	without	making any changes by using the	'q' option.

       The  MBR-to-GPT conversion will leave at	least one gap in the partition
       numbering if the	original MBR used logical partitions. These  gaps  are
       harmless,  but  you  can	eliminate them by using	the 's'	option,	if you
       like.  (Doing this may require you to update your /etc/fstab file.)

       When creating a fresh partition table, certain considerations may be in
       order:

       *      For data (non-boot) disks, and for boot disks used on BIOS-based
	      computers	with GRUB as the boot loader, partitions may  be  cre-
	      ated in whatever order and in whatever sizes are desired.

       *      Boot disks for EFI-based systems require an EFI System Partition
	      (gdisk internal code 0xEF00) formatted as	FAT-32.	I  recommended
	      making  this  partition  550  MiB. (Smaller ESPs are common, but
	      some EFIs	have flaky FAT drivers that necessitate	a larger  par-
	      tition  for  reliable  operation.) Boot-related files are	stored
	      here. (Note that GNU Parted identifies such partitions as	having
	      the "boot	flag" set.)

       *      Some boot	loaders	for BIOS-based systems make use	of a BIOS Boot
	      Partition	(gdisk internal	code 0xEF02), in which	the  secondary
	      boot  loader  is	stored,	 possibly  without  the	 benefit  of a
	      filesystem. (GRUB2 may optionally	use such  a  partition.)  This
	      partition	 can  typically	be quite small (roughly	32 to 200 KiB,
	      although 1 MiB is	more common in practice), but you should  con-
	      sult your	boot loader documentation for details.

       *      If  Windows  is to boot from a GPT disk, a partition of type Mi-
	      crosoft Reserved (gdisk internal code  0x0C01)  is  recommended.
	      This  partition  should  be about	128 MiB	in size. It ordinarily
	      follows the EFI System Partition and  immediately	 precedes  the
	      Windows  data  partitions. (Note that old	versions of GNU	Parted
	      create all FAT partitions	as this	type, which actually makes the
	      partition	 unusable  for normal file storage in both Windows and
	      Mac OS X.)

       *      Some OSes' GPT utilities create some blank space (typically  128
	      MiB)  after  each	partition. The intent is to enable future disk
	      utilities	to use this space. Such	free space is not required  of
	      GPT  disks, but creating it may help in future disk maintenance.
	      You can use GPT fdisk's relative	partition  positioning	option
	      (specifying  the	starting  sector  as '+128M', for instance) to
	      simplify creating	such gaps.

OPTIONS
       -l     List the partition table for the specified device	and  then  ex-
	      its.

       Most  interactions  with	 gdisk	occur  with  its interactive text-mode
       menus. Three menus exist: the main menu,	the recovery &	transformation
       menu,  and the experts' menu. The main menu provides the	functions that
       are most	likely to be useful for	typical	partitioning  tasks,  such  as
       creating	and deleting partitions, changing partition type codes,	and so
       on. Specific functions are:

       b      Save partition data to a backup file. You	can back up your  cur-
	      rent in-memory partition table to	a disk file using this option.
	      The resulting file is a binary file consisting of	the protective
	      MBR, the main GPT	header,	the backup GPT header, and one copy of
	      the partition table, in that order. Note that the	backup	is  of
	      the current in-memory data structures, so	if you launch the pro-
	      gram, make changes, and then use this option,  the  backup  will
	      reflect  your  changes.  Note also that the restore option is on
	      the recovery & transformation menu; the backup option is on  the
	      main menu	to encourage its use.

       c      Change  the  GPT	name of	a partition. This name is encoded as a
	      UTF-16 string, but proper	entry and display of  anything	beyond
	      basic  ASCII  values  requires suitable locale and font support.
	      For the most part, Linux ignores the partition name, but it  may
	      be  important  in	some OSes. GPT fdisk sets a default name based
	      on the partition type code. Note that the	GPT partition name  is
	      different	 from  the  filesystem	name,  which is	encoded	in the
	      filesystem's data	structures.

       d      Delete a partition. This action deletes the entry	from the  par-
	      tition  table  but  does not disturb the data within the sectors
	      originally allocated to the partition on the disk. If  a	corre-
	      sponding hybrid MBR partition exists, gdisk deletes it, as well,
	      and expands any adjacent 0xEE (EFI GPT) MBR protective partition
	      to fill the new free space.

       i      Show  detailed  partition	 information.  The summary information
	      produced by the 'p' command necessarily omits many details, such
	      as  the  partition's  unique GUID	and the	translation of gdisk's
	      internal partition type code to a	plain type name. The  'i'  op-
	      tion displays this information for a single partition.

       l      Display  a  summary of partition types. GPT uses a GUID to iden-
	      tify partition types for particular OSes and purposes. For  ease
	      of  data entry, gdisk compresses these into two-byte (four-digit
	      hexadecimal) values that are related  to	their  equivalent  MBR
	      codes.  Specifically,  the MBR code is multiplied	by hexadecimal
	      0x0100. For instance, the	code for Linux swap space  in  MBR  is
	      0x82,  and  it's 0x8200 in gdisk.	A one-to-one correspondence is
	      impossible, though. Most notably,	the codes for all varieties of
	      FAT  and NTFS partition correspond to a single GPT code (entered
	      as 0x0700	in gdisk). Some	OSes use a single MBR code but	employ
	      many  more  codes	in GPT.	For these, gdisk adds code numbers se-
	      quentially, such as 0xa500 for a FreeBSD disklabel,  0xa501  for
	      FreeBSD  boot,  0xa502  for  FreeBSD  swap, and so on. Note that
	      these two-byte codes are unique to gdisk.	The type code list may
	      optionally  be filtered by a search string; for instance,	enter-
	      ing linux	shows only partition type codes	with descriptions that
	      include the string Linux.	This search is performed case-insensi-
	      tively.

       n      Create a new partition. This command is modeled after the	equiv-
	      alent fdisk option, although some	differences exist. You enter a
	      partition	number,	starting sector, and an	 ending	 sector.  Both
	      start and	end sectors can	be specified in	absolute terms as sec-
	      tor numbers or as	positions measured in kibibytes	(K), mebibytes
	      (M),  gibibytes  (G),  tebibytes	(T), or	pebibytes (P); for in-
	      stance, 40M specifies a position 40MiB from  the	start  of  the
	      disk.  You can specify locations relative	to the start or	end of
	      the specified default range by preceding the number by a '+'  or
	      '-'  symbol, as in +2G to	specify	a point	2GiB after the default
	      start sector, or -200M to	specify	a point	200MiB before the last
	      available	sector.	Pressing the Enter key with no input specifies
	      the default value, which is the start of the  largest  available
	      block for	the start sector and the end of	the same block for the
	      end sector.

       o      Clear out	all partition data. This includes GPT header data, all
	      partition	definitions, and the protective	MBR. The sector	align-
	      ment is reset to the default (1 MiB, or 2048 sectors on  a  disk
	      with 512-byte sectors).

       p      Display  basic  partition	 summary data. This includes partition
	      numbers, starting	and ending sector  numbers,  partition	sizes,
	      gdisk's  partition  types	 codes,	and partition names. For addi-
	      tional information, use the 'i' command.

       q      Quit from	the program without saving your	changes.  Use this op-
	      tion  if	you  just  wanted to view information or if you	make a
	      mistake and want to back out of all your changes.

       r      Enter the	recovery & transformation  menu.  This	menu  includes
	      emergency	 recovery options (to fix damaged GPT data structures)
	      and options to transform to or from other	partitioning  systems,
	      including	creating hybrid	MBRs.

       s      Sort partition entries. GPT partition numbers need not match the
	      order of partitions on the disk. If you want them	to match,  you
	      can use this option.  Note that some partitioning	utilities sort
	      partitions whenever they make changes. Such changes will be  re-
	      flected  in  your	 device	 filenames,  so	 you  may need to edit
	      /etc/fstab if you	use this option.

       t      Change a single partition's type code. You enter the  type  code
	      using  a	two-byte hexadecimal number, as	described earlier. You
	      may also enter a GUID  directly,	if  you	 have  one  and	 gdisk
	      doesn't know it.

       v      Verify  disk. This option	checks for a variety of	problems, such
	      as incorrect CRCs	and mismatched main and	backup data. This  op-
	      tion  does  not automatically correct most problems, though; for
	      that, you	must use options  on  the  recovery  &	transformation
	      menu.  If	no problems are	found, this command displays a summary
	      of unallocated disk space.

       w      Write data. Use this command to save your	changes.

       x      Enter the	experts' menu. Using this option  provides  access  to
	      features you can use to get into even more trouble than the main
	      menu allows.

       ?      Print the	menu. Type this	command	 (or  any  other  unrecognized
	      command) to see a	summary	of available options.

       The second gdisk	menu is	the recovery & transformation menu, which pro-
       vides access to data recovery  options  and  features  related  to  the
       transformation  of  partitions between partitioning schemes (converting
       BSD disklabels into GPT partitions or creating  hybrid  MBRs,  for  in-
       stance).	  A  few  options  on this menu	duplicate functionality	on the
       main menu, for the sake of convenience. The options on this menu	are:

       b      Rebuild GPT header from backup.  You  can	 use  the  backup  GPT
	      header  to  rebuild  the	main GPT header	with this option. It's
	      likely to	be useful if your main GPT header was damaged  or  de-
	      stroyed (say, by sloppy use of dd).

       c      Load  backup  partition  table.  Ordinarily, gdisk uses only the
	      main partition table (although the backup's integrity is checked
	      when  you	 launch	 the program). If the main partition table has
	      been damaged, you	can use	this option to load  the  backup  from
	      disk  and	 use  it instead. Note that this will almost certainly
	      produce no or strange partition entries if you've	just converted
	      an  MBR disk to GPT format, since	there will be no backup	parti-
	      tion table on disk.

       d      Use main GPT header and  rebuild	the  backup.  This  option  is
	      likely to	be useful if the backup	GPT header has been damaged or
	      destroyed.

       e      Load main	partition table. This option reloads the  main	parti-
	      tion  table  from	 disk. It's only likely	to be useful if	you've
	      tried to use the backup partition	table (via 'c')	 but  it's  in
	      worse shape then the main	partition table.

       f      Load  MBR	 and  build fresh GPT from it. Use this	option if your
	      GPT is corrupt or	conflicts with the MBR and you want to use the
	      MBR as the basis for a new set of	GPT partitions.

       g      Convert GPT into MBR and exit. This option converts as many par-
	      titions as possible into MBR form, destroys the GPT data	struc-
	      tures,  saves the	new MBR, and exits.  Use this option if	you've
	      tried GPT	and find that MBR works	better	for  you.   Note  that
	      this  function  generates	 up  to	four primary MBR partitions or
	      three primary partitions and as many logical partitions  as  can
	      be generated. Each logical partition requires at least one unal-
	      located block immediately	before its first block.	Therefore,  it
	      may be possible to convert a maximum of four partitions on disks
	      with tightly-packed partitions; however, if free space  was  in-
	      serted  between  partitions  when	 they were created, and	if the
	      disk is under 2 TiB in size, it should be	 possible  to  convert
	      all the partitions to MBR	form.  See also	the 'h'	option.

       h      Create  a	 hybrid	 MBR.  This is an ugly workaround that enables
	      GPT-unaware OSes,	or those that can't boot from a	GPT  disk,  to
	      access up	to three of the	partitions on the disk by creating MBR
	      entries for them.	Note that these	hybrid MBR entries can	easily
	      go  out  of  sync	 with  the  GPT	entries, particularly when hy-
	      brid-unaware GPT utilities are used to edit the disk.  Thus, you
	      may  need	to re-create the hybrid	MBR if you use such tools. Un-
	      like the 'g' option, this	option does not	support	converting any
	      partitions into MBR logical partitions.

       i      Show detailed partition information. This	option is identical to
	      the 'i' option on	the main menu.

       l      Load partition data from a backup	file. This option is  the  re-
	      verse  of	 the  'b' option on the	main menu. Note	that restoring
	      partition	data from anything but the original disk is not	recom-
	      mended.

       m      Return  to  the  main  menu.  This  option  enables you to enter
	      main-menu	commands.

       o      Print protective MBR data. You can see a summary of the  protec-
	      tive  MBR's  partitions with this	option.	This may enable	you to
	      spot glaring problems or help identify the partitions in	a  hy-
	      brid MBR.

       p      Print  the  partition table. This	option is identical to the 'p'
	      option in	the main menu.

       q      Quit without saving changes. This	option is identical to the 'q'
	      option in	the main menu.

       t      Transform	 BSD partitions	into GPT partitions. This option works
	      on BSD disklabels	held within GPT	(or converted MBR) partitions.
	      Converted	 partitions'  type codes are likely to need manual ad-
	      justment.	gdisk will attempt to convert BSD disklabels stored on
	      the  main	 disk  when launched, but this conversion is likely to
	      produce first and/or last	partitions that	are unusable. The many
	      BSD variants means that the probability of gdisk being unable to
	      convert a	BSD disklabel is high compared to  the	likelihood  of
	      problems with an MBR conversion.

       v      Verify  disk.  This option is identical to the 'v' option	in the
	      main menu.

       w      Write table to disk and exit. This option	is  identical  to  the
	      'w' option in the	main menu.

       x      Enter the	experts' menu. This option is identical	to the 'x' op-
	      tion in the main menu.

       ?      Print the	menu. This option (or any unrecognized entry) displays
	      a	summary	of the menu options.

       The  third gdisk	menu is	the experts' menu. This	menu provides advanced
       options that aren't closely related to recovery or  transformation  be-
       tween partitioning systems. Its options are:

       a      Set  attributes. GPT provides a 64-bit attributes	field that can
	      be used to set features for each partition. gdisk	supports  four
	      attributes:  system partition, read-only,	hidden,	and do not au-
	      tomount. You can set other attributes, but their numbers	aren't
	      translated  into anything	useful.	In practice, most OSes seem to
	      ignore these attributes.

       c      Change partition GUID. You can enter a custom unique GUID	for  a
	      partition	 using this option. (Note this refers to the GUID that
	      uniquely identifies a partition, not to its type code, which you
	      can change with the 't' main-menu	option.) Ordinarily, gdisk as-
	      signs this number	randomly; however, you might  want  to	adjust
	      the number manually if you've wound up with the same GUID	on two
	      partitions because of buggy GUID assignments (hopefully  not  in
	      gdisk) or	sheer incredible coincidence.

       d      Display  the  sector alignment value. See	the description	of the
	      'l' option for more details.

       e      Move backup GPT data structures to the end of the	disk. Use this
	      command  if  you've added	disks to a RAID	array, thus creating a
	      virtual disk with	space that follows the backup GPT data	struc-
	      tures.  This command moves the backup GPT	data structures	to the
	      end of the disk, where they belong.

       f      Randomize	the disk's GUID	and all	partitions' unique GUIDs  (but
	      not  their partition type	code GUIDs). This function may be used
	      after cloning a disk with	another	utility	in order to render all
	      GUIDs once again unique.

       g      Change  disk GUID. Each disk has a unique	GUID code, which gdisk
	      assigns randomly upon creation of	the GPT	data  structures.  You
	      can generate a fresh random GUID or enter	one manually with this
	      option.

       h      Recompute	CHS values in protective or hybrid  MBR.  This	option
	      can  sometimes  help if a	disk utility, OS, or BIOS doesn't like
	      the CHS values used by the partitions in the protective  or  hy-
	      brid  MBR.  In  particular, the GPT specification	requires a CHS
	      value of 0xFFFFFF	for over-8GiB partitions, but  this  value  is
	      technically  illegal by the usual	standards. Some	BIOSes hang if
	      they encounter this value. This option  will  recompute  a  more
	      normal  CHS value	-- 0xFEFFFF for	over-8GiB partitions, enabling
	      these BIOSes to boot.

       i      Show detailed partition information. This	option is identical to
	      the 'i' option on	the main menu.

       j      Adjust  the  location of the main	partition table. This value is
	      normally 2, but it may need to be	increased in some cases,  such
	      as  when	a system-on-chip (SoC) is hard-coded to	read boot code
	      from sector 2. I recommend against adjusting this	 value	unless
	      doing so is absolutely necessary.

       l      Change  the sector alignment value. Disks	with more logical sec-
	      tors per	physical  sectors  (such  as  modern  Advanced	Format
	      drives),	some  RAID  configurations,  and many SSD devices, can
	      suffer performance problems if partitions	are not	aligned	 prop-
	      erly for their internal data structures. On new disks, GPT fdisk
	      attempts to align	partitions on 1	MiB  boundaries	 (2048-sectors
	      on disks with 512-byte sectors) by default, which	optimizes per-
	      formance for all of these	disk types. On pre-partitioned	disks,
	      GPT  fdisk attempts to identify the alignment value used on that
	      disk, but	will set 8-sector alignment on disks larger  than  300
	      GB even if lesser	alignment values are detected. In either case,
	      it can be	changed	by using this option.

       m      Return to	the main  menu.	 This  option  enables	you  to	 enter
	      main-menu	commands.

       n      Create a new protective MBR. Use this option if the current pro-
	      tective MBR is damaged in	a way that gdisk doesn't automatically
	      detect  and correct, or if you want to convert a hybrid MBR into
	      a	"pure" GPT with	a conventional protective MBR.

       o      Print protective MBR data. You can see a summary of the  protec-
	      tive  MBR's  partitions with this	option.	This may enable	you to
	      spot glaring problems or help identify the partitions in	a  hy-
	      brid MBR.

       p      Print  the  partition table. This	option is identical to the 'p'
	      option in	the main menu.

       q      Quit without saving changes. This	option is identical to the 'q'
	      option in	the main menu.

       r      Enter  the recovery & transformations menu. This option is iden-
	      tical to the 'r' option on the main menu.

       s      Resize partition table. The default partition table size is  128
	      entries.	 Officially,  sizes  of	 less  than 16KB (128 entries,
	      given the	normal entry size) are unsupported by the GPT specifi-
	      cation;  however,	 in  practice they seem	to work, and can some-
	      times be useful in converting MBR	disks. Larger sizes also  work
	      fine.  OSes  may impose their own	limits on the number of	parti-
	      tions, though.

       t      Swap two partitions' entries in the partition table. One	parti-
	      tion  may	be empty. For instance,	if partitions 1-4 are defined,
	      transposing 1 and	5 results in a table with partitions  numbered
	      from  2-5.  Transposing  partitions in this way has no effect on
	      their disk space allocation; it only alters their	order  in  the
	      partition	table.

       u      Replicate	 the  current  device's	partition table	on another de-
	      vice. You	will be	prompted to type the  new  device's  filename.
	      After  the  write	 operation completes, you can continue editing
	      the original device's partition table.  Note that	the replicated
	      partition	 table	is  an exact copy, including all GUIDs;	if the
	      device should have its own unique	GUIDs, you should  use	the  f
	      option on	the new	disk.

       v      Verify  disk.  This option is identical to the 'v' option	in the
	      main menu.

       z      Zap (destroy) the	GPT data structures and	exit. Use this	option
	      if  you want to repartition a GPT	disk using fdisk or some other
	      GPT-unaware program.  You'll be given the	choice	of  preserving
	      the  existing  MBR,  in  case it's a hybrid MBR with salvageable
	      partitions or if you've already created new MBR  partitions  and
	      want to erase the	remnants of your GPT partitions. If you've al-
	      ready created new	MBR partitions,	it's conceivable that this op-
	      tion  will  damage the first and/or last MBR partitions! Such an
	      event is unlikely, but could occur if your  new  MBR  partitions
	      overlap the old GPT data structures.

       ?      Print the	menu. This option (or any unrecognized entry) displays
	      a	summary	of the menu options.

       In many cases, you can press the	Enter key to select a  default	option
       when entering data. When	only one option	is possible, gdisk usually by-
       passes the prompt entirely.

BUGS
       Known bugs and limitations include:

       *      The program compiles correctly only on Linux, FreeBSD, Mac OS X,
	      and  Windows.  Linux versions for	x86-64 (64-bit), x86 (32-bit),
	      and PowerPC (32-bit) have	been tested, with the  x86-64  version
	      having  seen  the	 most testing. Under FreeBSD, 32-bit (x86) and
	      64-bit (x86-64) versions have been tested. Only 32-bit  versions
	      for  Mac	OS  X  and Windows have	been tested by the author, al-
	      though I've heard	of 64-bit  versions  being  successfully  com-
	      piled.

       *      The  FreeBSD  version  of	the program can't write	changes	to the
	      partition	table to a disk	when existing partitions on that  disk
	      are  mounted.  (The  same	problem	exists with many other FreeBSD
	      utilities, such as gpt, fdisk, and dd.) This limitation  can  be
	      overcome	by  typing  sysctl  kern.geom.debugflags=16 at a shell
	      prompt.

       *      The fields used to display the start and end sector numbers  for
	      partitions  in  the  'p'	command	 are  14 characters wide. This
	      translates to a limitation of about 45 PiB. On larger disks, the
	      displayed	columns	will go	out of alignment.

       *      In  the  Windows version,	only ASCII characters are supported in
	      the  partition  name  field.  If	an  existing  partition	  uses
	      non-ASCII	 UTF-16	 characters, they're likely to be corrupted in
	      the 'i' and 'p' menu options' displays; however, they should  be
	      preserved	 when  loading	and  saving  partitions.  Binaries for
	      Linux, FreeBSD, and OS X support full UTF-16 partition names.

       *      The program can load only	up to 128 partitions (4	primary	parti-
	      tions  and 124 logical partitions) when converting from MBR for-
	      mat.  This  limit	 can  be  raised  by  changing	 the   #define
	      MAX_MBR_PARTS line in the	basicmbr.h source code file and	recom-
	      piling;  however,	 such  a   change   will   require   using   a
	      larger-than-normal partition table. (The limit of	128 partitions
	      was chosen because that number equals the	 128  partitions  sup-
	      ported by	the most common	partition table	size.)

       *      Converting  from	MBR format sometimes fails because of insuffi-
	      cient space at the start or (more	commonly) the end of the disk.
	      Resizing	the  partition	table (using the 's' option in the ex-
	      perts' menu) can sometimes overcome this	problem;  however,  in
	      extreme  cases  it  may be necessary to resize a partition using
	      GNU Parted or a similar tool prior to conversion with gdisk.

       *      MBR conversions work only	if the disk has	correct	LBA  partition
	      descriptors.  These  descriptors	should	be present on any disk
	      over 8 GiB in size or on smaller disks partitioned with any  but
	      very ancient software.

       *      BSD  disklabel  support  can create first	and/or last partitions
	      that overlap with	the GPT	data structures. This can sometimes be
	      compensated  by  adjusting  the partition	table size, but	in ex-
	      treme cases the affected partition(s) may	need to	be deleted.

       *      Because of the highly variable nature of	BSD  disklabel	struc-
	      tures,  conversions  from	 this form may be unreliable --	parti-
	      tions may	be dropped, converted in a way that  creates  overlaps
	      with  other partitions, or converted with	incorrect start	or end
	      values. Use this feature with caution!

       *      Booting after converting an MBR or BSD disklabel disk is	likely
	      to  be disrupted.	Sometimes re-installing	a boot loader will fix
	      the problem, but other times you may need	to switch  boot	 load-
	      ers.  Except  on	EFI-based  platforms, Windows through at least
	      Windows 7	doesn't	support	booting	from GPT disks.	Creating a hy-
	      brid  MBR	(using the 'h' option on the recovery &	transformation
	      menu) or abandoning GPT in favor of MBR may be your only options
	      in this case.

AUTHORS
       Primary author: Roderick	W. Smith (rodsmith@rodsbooks.com)

       Contributors:

       * Yves Blusseau (1otnwmz02@sneakemail.com)

       * David Hubbard (david.c.hubbard@gmail.com)

       * Justin	Maggard	(justin.maggard@netgear.com)

       * Dwight	Schauer	(dschauer@gmail.com)

       * Florian Zumbiehl (florz@florz.de)

SEE ALSO
       bsdlabel(8),   fdisk(8),	  fixparts(8),	 gdisk(8),  gpart(8),  gpt(8),
       newfs(8), sgdisk(8).

       http://en.wikipedia.org/wiki/GUID_Partition_Table

       http://developer.apple.com/technotes/tn2006/tn2166.html

       http://www.rodsbooks.com/gdisk/

AVAILABILITY
       The gdisk command is part of the	GPT fdisk  package  and	 is  available
       from Rod	Smith.

Roderick W. Smith		     1.0.5			      GDISK(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | BUGS | AUTHORS | SEE ALSO | AVAILABILITY

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=gdisk&sektion=8&manpath=FreeBSD+13.0-RELEASE+and+Ports>

home | help