Provided by: gdisk_1.0.1-1build1_i386 bug

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;
       however, 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   options  require  you  to  understand  the
       distinctions between the main and backup data, as well as  between  the
       GPT  headers  and the partition tables. For information on MBR vs. GPT,
       as well as GPT  terminology  and  structure,  see  the  extended  gdisk
       documentation at http://www.rodsbooks.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
       unmodified.

       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
       instance)  or raw disk images used by emulators such as QEMU or VMWare.
       Note that only raw disk images are  supported;  gdisk  cannot  work  on
       compressed 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
       PowerPC-based  Macintoshes.  Upon  exiting  with  the 'w' option, gdisk
       replaces the MBR or disklabel with a GPT. This  action  is  potentially
       dangerous!  Your system may become unbootable, and partition type codes
       may become corrupted if the disk uses  unrecognized  type  codes.  Boot
       problems  are  particularly  likely  if  you're  multi-booting with any
       GPT-unaware 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
              created 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.   The
              recommended size of this partition is between 100 and  300  MiB.
              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),
              but  you  should  consult  your  boot  loader  documentation for
              details.

       *      If Windows is to boot from a  GPT  disk,  a  partition  of  type
              Microsoft  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
              exits.

       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
              current 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 program, 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
              partition table but does not disturb the data within the sectors
              originally  allocated  to  the  partition  on  the  disk.  If  a
              corresponding 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'
              option displays this information for a single partition.

       l      Display a summary  of  partition  types.  GPT  uses  a  GUID  to
              identify  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 sgdisk). Some OSes use a
              single MBR code but employ many more codes in  GPT.  For  these,
              gdisk  adds  code  numbers  sequentially,  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.

       n      Create a new partition.  This  command  is  modelled  after  the
              equivalent  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
              sector numbers  or  as  positions  measured  in  kibibytes  (K),
              mebibytes  (M),  gibibytes (G), tebibytes (T), or pebibytes (P);
              for instance, 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
              alignment is reset to the default (1MB, 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
              additional information, use the 'i' command.

       q      Quit from the program without saving  your  changes.   Use  this
              option  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
              reflected  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
              option 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
       provides 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
       instance).   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
              destroyed (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
              partition 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
              partition  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
              partitions as possible into MBR  form,  destroys  the  GPT  data
              structures,  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
              unallocated 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
              inserted  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
              hybrid-unaware GPT utilities are used to edit the  disk.   Thus,
              you  may need to re-create the hybrid MBR if you use such tools.
              Unlike 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
              reverse  of the 'b' option on the main menu. Note that restoring
              partition data from  anything  but  the  original  disk  is  not
              recommended.

       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
              protective  MBR's  partitions  with this option. This may enable
              you to spot glaring problems or help identify the partitions  in
              a hybrid 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
              adjustment. 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'
              option 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
       between 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
              automount. 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
              assigns 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
              structures. 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
              hybrid  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.

       l      Change  the  sector  alignment  value.  Disks  with more logical
              sectors 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
              properly  for  their internal data structures. On new disks, GPT
              fdisk  attempts  to  align   partitions   on   1MiB   boundaries
              (2048-sectors  on disks with 512-byte sectors) by default, which
              optimizes  performance  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
              protective   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
              protective MBR's partitions with this option.  This  may  enable
              you  to spot glaring problems or help identify the partitions in
              a hybrid 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
              identical 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
              specification; however, in practice they seem to work,  and  can
              sometimes  be  useful in converting MBR disks. Larger sizes also
              work fine. OSes may impose their own limits  on  the  number  of
              partitions, though.

       t      Swap  two  partitions'  entries  in  the  partition  table.  One
              partition 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
              device.  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
              already  created  new MBR partitions, it's conceivable that this
              option 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
       bypasses 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,
              although  I've  heard  of  64-bit  versions  being  successfully
              compiled.

       *      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
              partitions and 124 logical partitions) when converting from  MBR
              format.  This  limit  can  be  raised  by  changing  the #define
              MAX_MBR_PARTS line  in  the  basicmbr.h  source  code  file  and
              recompiling;  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
              supported by the most common partition table size.)

       *      Converting  from  MBR  format   sometimes   fails   because   of
              insufficient  space  at  the start or (more commonly) the end of
              the disk. Resizing the partition table (using the 's' option  in
              the experts' 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
              extreme cases the affected partition(s) may need to be deleted.

       *      Because   of   the  highly  variable  nature  of  BSD  disklabel
              structures, conversions from this  form  may  be  unreliable  --
              partitions  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
              loaders. Except on EFI-based platforms, Windows through at least
              Windows  7  doesn't  support  booting from GPT disks. Creating a
              hybrid  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

       cfdisk (8), cgdisk (8), fdisk (8), mkfs (8),  parted  (8),  sfdisk  (8)
       sgdisk (8) fixparts (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.