# SGDISK - Command-line GUID partition table (GPT) manipulator fo... - man(8) - [phpMan]

[_SGDISK_(8)](https://www.chedong.com/phpMan.php/man/SGDISK/8/markdown)                                 GPT fdisk Manual                                 [_SGDISK_(8)](https://www.chedong.com/phpMan.php/man/SGDISK/8/markdown)

## NAME
       sgdisk - Command-line GUID partition table (GPT) manipulator for Linux and Unix

## SYNOPSIS
       **sgdisk **[ options ] _device_


## DESCRIPTION
       GPT  fdisk  is a text-mode menu-driven package for creation and manipulation of partition ta‐
       bles. It consists of two programs: the  text-mode  interactive  **gdisk  **and  the  command-line
       **sgdisk**.  Either program will automatically convert an old-style Master Boot Record (MBR) par‐
       tition 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.
       This man page documents the command-line **sgdisk **program.

       Some advanced data manipulation and recovery options require you to understand  the  distinc‐
       tions  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 ex‐
       tended **gdisk **documentation at _<https://www.rodsbooks.com/gdisk/_> or consult Wikipedia.

       The **sgdisk **program employs a user interface that's based entirely on the command line, making
       it suitable for use in scripts or by experts who want to make one or two quick changes  to  a
       disk.  (The program may query the user when certain errors are encountered, though.) The pro‐
       gram's name is based on **sfdisk**, but the user options of the two programs are entirely differ‐
       ent from one another.

       Ordinarily, **sgdisk **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 oper‐
       ate 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; **sgdisk **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 **sgdisk**, do not
       need to deal with CHS geometries and all the problems they create.

       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**, **sgdisk**, or GNU Parted programs.

       Upon start, **sgdisk **attempts to identify the partition type in use on the disk.  If  it  finds
       valid  GPT  data, **sgdisk **will use it. If **sgdisk **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. If you specify any option that
       results  in  changes  to  an MBR or BSD disklabel, **sgdisk **ignores those changes unless the _-g_
       (_--mbrtogpt_), _-z_ (_--zap_), or _-Z_ (_--zap-all_) option is used. If you use the _-g_ option,  **sgdisk**
       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  unrec‐
       ognized  type  codes.  Boot problems are particularly likely if you're multi-booting with any
       GPT-unaware OS.

       The MBR-to-GPT conversion will leave at least one gap in the partition numbering if the orig‐
       inal MBR used logical partitions. These gaps are harmless, but you can eliminate them by  us‐
       ing  the  _-s_  (_--sort_)  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.  I recommended making this partition 550 MiB. (Smaller
              ESPs are common, but some EFIs have flaky FAT drivers that necessitate a larger parti‐
              tion 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 **in‐
              ternal 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 parti‐
              tion can typically be quite small (roughly 32 to 200 KiB, although 1 MiB is more  com‐
              mon in practice), 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_ (**sgdisk**
              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 GNU Parted creates 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 parti‐
              tion. 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.


## OPTIONS
       Some options take no arguments, others take one argument (typically a partition number),  and
       others take compound arguments with colon delimitation. For instance, _-n_ (_--new_) takes a par‐
       tition  number,  a  starting  sector  number,  and  an  ending sector number, as in **sgdisk -n**
       **2:2000:50000 /dev/sdc**, which creates a new partition, numbered 2, starting at sector 2000  an
       ending at sector 50,000, on _/dev/sdc_.

       Unrelated  options may be combined; however, some such combinations will be nonsense (such as
       deleting a partition and then changing its GUID type code).  **sgdisk **interprets options in the
       order in which they're entered, so effects can vary depending on order. For instance,  **sgdisk**
### -s  -d 2 
       list; but **sgdisk -d 2 -s **deletes the original partition 2 and then sorts the modified  parti‐
       tion table.

       Error checking and opportunities to correct mistakes in **sgdisk **are minimal. Although the pro‐
       gram endeavors to keep the GPT data structures legal, it does not prompt for verification be‐
       fore performing its actions. Unless you require a command-line-driven program, you should use
       the  interactive  **gdisk **instead of **sgdisk**, since **gdisk **allows you to quit without saving your
       changes, should you make a mistake.

       Although **sgdisk **is based on the same partition-manipulation code as **gdisk**, **sgdisk  **implements
       fewer features than its interactive sibling. Options available in **sgdisk **are:


### -a, --set-alignment=value
              Set the sector alignment multiple. GPT fdisk aligns the start of partitions to sectors
              that are multiples of this value, which defaults to 1 MiB (2048 on disks with 512-byte
              sectors) on freshly formatted disks. This alignment value is necessary to obtain opti‐
              mum  performance  with  Western Digital Advanced Format and similar drives with larger
              physical than logical sector sizes, with some types of RAID arrays, and with  SSD  de‐
              vices. When the _-I_ option is used, this same alignment value is used to determine par‐
              tition  end  points;  but partitions end at one less than a multiple of this value, to
              keep the partition length a multiple of this value.


### -A, --attributes=list|[partnum:show|or|nand|xor|=|set|clear|toggle|get[:bitnum|hexbitmask]]
              View or set partition attributes. Use _list_ to see defined  (known)  attribute  values.
              Omit  the  partition number (and even the device filename) when using this option. The
              others require a partition number. The _show_ and _get_ options show the current attribute
              settings (all attributes or for a particular bit, respectively). The _or_, _nand_, _xor_, _=_,
              _set_, _clear_, and _toggle_ options enable you to change the attribute bit value. The  _set_,
              _clear_,  _toggle_, and _get_ options work on a bit number; the others work on a hexadecimal
              bit mask. For example, type **sgdisk -A 4:set:2 /dev/sdc **to  set  the  bit  2  attribute
              (legacy BIOS bootable) on partition 4 on _/dev/sdc_.


### -b, --backup=file
              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. If the GPT data structures are damaged, the backup
              may not accurately reflect the damaged state; instead, they will reflect  GPT  fdisk's
              first-pass interpretation of the GPT.


### -B, --byte-swap-name=partnum
              Swap  the byte order for the name of the specified partition. Some partitioning tools,
              including GPT fdisk 1.0.7 and earlier, can write the partition name in the wrong  byte
              order on big-endian computers, such as the IBM s390 mainframes and PowerPC-based Macs.
              This feature corrects this problem.


### -c, --change-name=partnum:name
              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  lo‐
              cale and font support. For the most part, Linux ignores the partition name, but it may
              be important in some OSes. If you want to set a name that includes a space, enclose it
              in  quotation  marks, as in _sgdisk_ _-c_ _1:"Sample_ _Name"_ _/dev/sdb_. Note that the GPT name
              of a partition is distinct from the filesystem name, which is encoded in the  filesys‐
              tem's data structures.


### -C, --recompute-chs
              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.


### -d, --delete=partnum
              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.


### -D, --display-alignment
              Display current sector alignment value. Partitions will be created on multiples of the
              sector  value  reported by this option. You can change the alignment value with the -a
              option.


### -e, --move-second-header
              Move backup GPT data structures to the end of the disk.  Use  this  option  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.


### -E, --end-of-largest
              Displays the sector number of the end of the largest available block of sectors on the
              disk.  A script may store this value and pass it back as part of _-n_'s option to create
              a partition. If no unallocated sectors are available, this function returns the  value
              0.


### -f, --first-in-largest
              Displays  the  sector number of the start of the largest available block of sectors on
              the disk. A script may store this value and pass it back as part  of  _-n_'s  option  to
              create a partition. If no unallocated sectors are available, this function returns the
              value  0.  Note that this parameter is blind to partition alignment; when you actually
              create a partition, its start point might be changed from this value.


### -F, --first-aligned-in-largest
              Similar to _-f_ (_--first-in-largest_), except returns the sector number with the  current
              alignment correction applied. Use this function if you need to compute the actual par‐
              tition  start point rather than a theoretical start point or the actual start point if
              you set the alignment value to 1.


### -g, --mbrtogpt
              Convert an MBR or BSD disklabel disk to a GPT disk. As a safety measure, use  of  this
              option  is  required on MBR or BSD disklabel disks if you intend to save your changes,
              in order to prevent accidentally damaging such disks.


### -G, --randomize-guids
              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 in order to render
              all GUIDs once again unique.


### -h, --hybrid
              Create a hybrid MBR. This option takes from one to three partition numbers,  separated
              by colons, as arguments. You may optionally specify a final partition "EE" to indicate
              that  the EFI GPT (type 0xEE) should be placed last in the table, otherwise it will be
              placed first, followed by the partition(s) you specify.  Their type codes are based on
              the GPT fdisk type codes divided by 0x0100, which is usually correct for Windows  par‐
              titions. If the active/bootable flag should be set, you must do so in another program,
              such as **fdisk**. The **gdisk **program offers additional hybrid MBR creation options.


### -i, --info=partnum
              Show  detailed  partition information. The summary information produced by the _-p_ com‐
              mand necessarily omits many details, such as  the  partition's  unique  GUID  and  the
              translation  of **sgdisk**'s internal partition type code to a plain type name. The _-i_ op‐
              tion displays this information for a single partition.


### -I, --align-end
              When possible, align the end points of partitions to one less than a multiple  of  the
              alignment value. When both start and end points are aligned, partitions should be mul‐
              tiples  of  the alignment value in size, which is necessary for some partition encryp‐
              tion tools to function correctly. This option applies to all partitions created  **after**
              this  option on the command line. Note that this alignment is not always possible; for
              instance, if the free space at the end of a disk is less  than  the  alignment  value,
              with  the  current  final  partition being aligned, and if **sgdisk **is asked to create a
              partition in that space, then it will **not **be end-aligned.


### -j, --move-main-table=sector
              Sets the start sector 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.


### -k, --move-backup-table=sector
              Sets  the  start sector of the second/backup partition table. The backup table is usu‐
              ally placed just before the last sector, which holds the backup header.   The  default
              value  is  thus the size of the disk, minus one, minus the total size of the partition
              table (in sectors, usually 32).  There are probably very few reasons  to  ever  change
              this,  and while the EFI standard does not mandate it, most tooling assumes the backup
              table to be at the very end of the disk.


### -l, --load-backup=file
              Load partition data from a backup file. This option is the reverse of the  _-b_  option.
              Note  that  restoring partition data from anything but the original disk is not recom‐
              mended. This option will work even if the disk's original partition table is bad; how‐
              ever, most other options on the same command line will be ignored.


### -L, --list-types
              Display a summary of partition types. GPT uses a GUID to identify partition types  for
              particular  OSes  and  purposes.  For ease of data entry, **sgdisk **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, **sgdisk **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  **and  **sgdisk**.  This  option  does not require you to specify a valid disk device
              filename.


### -m, --gpttombr
              Convert disk from GPT to MBR form. This option takes from one to four  partition  num‐
              bers,  separated  by colons, as arguments. Their type codes are based on the GPT fdisk
              type codes divided by 0x0100. If the active/bootable flag should be set, you  must  do
              so in another program, such as **fdisk**.  The **gdisk **program offers additional MBR conver‐
              sion  options. It is not possible to convert more than four partitions from GPT to MBR
              form or to convert partitions that start above the 2TiB mark or that are  larger  than
              2TiB.


### -n, --new=partnum:start:end
              Create  a  new partition. You enter a partition number, starting sector, and an ending
              sector. Both start and end sectors can be specified in absolute terms as  sector  num‐
              bers  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 spec‐
              ified default range by preceding the number by a '+' or '-' symbol, as in **+2G **to spec‐
              ify a point 2GiB after the default start sector, or **-200M **to specify  a  point  200MiB
              before  the  last  available  sector.  A start or end value of 0 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. A partnum value of 0 causes the program to
              use the first available partition number. Subsequent uses of the _-A_ (_--attributes_), _-c_
              (_--change-name_), _-t_ (_--typecode_), and _-u_ (_--partition-guid_) options may also use _0_  to
              refer to the same partition.


### -N, --largest-new=num
              Create  a  new  partition that fills the largest available block of space on the disk.
              You can use the _-a_ (_--set-alignment_) option to adjust the alignment, if desired. A num
              value of 0 causes the program to use the first available partition number.  Subsequent
              uses  of  the _-A_ (_--attributes_), _-c_ (_--change-name_), _-t_ (_--typecode_), and _-u_ (_--parti‐_
              _tion-guid_) options may also use _0_ to refer to the same partition.


### -o, --clear
              Clear out all partition data. This includes GPT header  data,  all  partition  defini‐
              tions,  and  the protective MBR. Note that this operation will, like most other opera‐
              tions, fail on a damaged disk. If you want to prepare a disk you know  to  be  damaged
              for GPT use, you should first wipe it with -Z and then partition it normally. This op‐
              tion will work even if the disk's original partition table is bad; however, most other
              options on the same command line will be ignored.


### -O, --print-mbr
              Display  basic  _MBR_  partition summary data. This includes partition numbers, starting
              and ending sector numbers, partition sizes, MBR partition types codes,  and  partition
              names.  This option is useful mainly for diagnosing partition table problems, particu‐
              larly on disks with hybrid MBRs.


### -p, --print
              Display basic GPT partition summary data. This includes  partition  numbers,  starting
              and ending sector numbers, partition sizes, **sgdisk**'s partition types codes, and parti‐
              tion names. For additional information, use the _-i_ (_--info_) option.


### -P, --pretend
              Pretend to make specified changes. In-memory GPT data structures are altered according
              to other parameters, but changes are not written to disk.


### -r, --transpose
              Swap  two  partitions'  entries  in the partition table. One or both partitions may be
              empty, although swapping two empty partitions is pointless. For  instance,  if  parti‐
              tions 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 alloca‐
              tion; it only alters their order in the partition table.


### -R, --replicate=second_device_filename
              Replicate the main device's partition table on the specified second device.  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 -G option on the new disk.


### -s, --sort
              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 par‐
              titioning 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, --typecode=partnum:{hexcode|GUID}
              Change a single partition's type code. You enter the type code using either a two-byte
              hexadecimal  number,  as  described  earlier, or a fully-specified GUID value, such as
              EBD0A0A2-B9E5-4433-87C0-68B6B72699C7.


### -T, --transform-bsd=partnum
              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. **sgdisk **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
              **sgdisk  **being  unable to convert a BSD disklabel is high compared to the likelihood of
              problems with an MBR conversion.


### -u, --partition-guid=partnum:guid
              Set the partition unique GUID for an individual partition. The GUID may be a  complete
              GUID or 'R' to set a random GUID.


### -U, --disk-guid=guid
              Set  the  GUID  for  the  disk. The GUID may be a complete GUID or 'R' to set a random
              GUID.


### --usage
              Print a brief summary of available options.


### -v, --verify
              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 prob‐
              lems, 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. This
              option  will  work  even  if the disk's original partition table is bad; however, most
              other options on the same command line will be ignored.


### -V, --version
              Display program version information. This option may be used without specifying a  de‐
              vice filename.


### -z, --zap
              Zap  (destroy)  the  GPT data structures and then exit. Use this option if you want to
              repartition a GPT disk using **fdisk **or some other GPT-unaware program. This option  de‐
              stroys  only  the  GPT data structures; it leaves the MBR intact. This makes it useful
              for wiping out GPT data structures after a disk has been repartitioned for MBR using a
              GPT-unaware utility; however, there's a risk that it will damage boot loaders or  even
              the  start of the first or end of the last MBR partition. If you use it on a valid GPT
              disk, the MBR will be left with an inappropriate EFI GPT (0xEE) partition  definition,
              which you can delete using another utility.


### -Z, --zap-all
              Zap  (destroy)  the  GPT and MBR data structures and then exit. This option works much
              like _-z_, but as it wipes the MBR as well as the GPT, it's more suitable if you want to
              repartition a disk after using this option, and completely unsuitable  if  you've  al‐
              ready repartitioned the disk.


### -?, --help
              Print a summary of options.


## RETURN VALUES
       **sgdisk **returns various values depending on its success or failure:


       **0      **Normal program execution


       **1      **Too few arguments


       **2      **An error occurred while reading the partition table


       **3      **Non-GPT disk detected and no _-g_ option, but operation requires a write action


       **4      **An error prevented saving changes


       **5      **An  error  occurred  while reading standard input (should never occur with sgdisk, but
              may with gdisk)


       **8      **Disk replication operation (-R) failed


## BUGS
       Known bugs and limitations include:


       ***      **The program compiles correctly only on Linux, FreeBSD, and Mac OS  X.  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.


       ***      **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_
              option are 14 characters wide. This translates to a limitation of  about  45  PiB.  On
              larger disks, the displayed columns will go out of alignment.


       ***      **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; how‐
              ever, 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 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 de‐
              scriptors should be present on any disk over 8 GiB in size or on smaller disks  parti‐
              tioned 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  ta‐
              ble 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 cre‐
              ates 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. Some‐
              times  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  Win‐
              dows 7 RC 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 (<das@teegra.net>)

       * Florian Zumbiehl (<florz@florz.de>)



## SEE ALSO
       [**cfdisk**(8)](https://www.chedong.com/phpMan.php/man/cfdisk/8/markdown), [**cgdisk**(8)](https://www.chedong.com/phpMan.php/man/cgdisk/8/markdown), [**fdisk**(8)](https://www.chedong.com/phpMan.php/man/fdisk/8/markdown), [**gdisk**(8)](https://www.chedong.com/phpMan.php/man/gdisk/8/markdown), [**mkfs**(8)](https://www.chedong.com/phpMan.php/man/mkfs/8/markdown), [**parted**(8)](https://www.chedong.com/phpMan.php/man/parted/8/markdown), [**sfdisk**(8)](https://www.chedong.com/phpMan.php/man/sfdisk/8/markdown), [**fixparts**(8)](https://www.chedong.com/phpMan.php/man/fixparts/8/markdown).

       _<https://en.wikipedia.org/wiki/GUID_Partition_Table_>

       _<https://developer.apple.com/technotes/tn2006/tn2166.html_>

       _<https://www.rodsbooks.com/gdisk/_>


## AVAILABILITY
       The **sgdisk **command is part of the _GPT_ _fdisk_ package and is available from Rod Smith.

Roderick W. Smith                              1.0.10                                      [_SGDISK_(8)](https://www.chedong.com/phpMan.php/man/SGDISK/8/markdown)
