1 .\" Copyright (c) 2002 Marcel Moolenaar
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27 .Dd September 28, 2009
32 .Nd "GUID partition table maintenance utility"
35 .Op Ar general_options
37 .Op Ar command_options
42 utility provides the necessary functionality to manipulate GUID partition
43 tables (GPTs), but see
45 below for how and where functionality is missing.
46 GPT partitions are accessed as
48 disk slices, with same number as GPT partition,
49 127 slices per disk device are supported.
50 The basic usage model of the
52 tool follows that of the
55 The general options are described in the following paragraph.
56 The remaining paragraphs describe the individual commands with their options.
57 Here we conclude by mentioning that a
59 is either a special file
60 corresponding to a disk-like device or a regular file.
61 The command is applied to each
63 listed on the command line.
65 The general options allow the user to change default settings or otherwise
66 change the behaviour that is applicable to all commands.
67 Not all commands use all default settings, so some general options may not
68 have an effect on all commands.
72 option allows the user to change the number of partitions the GPT can
74 This is used whenever a new GPT is created.
77 utility will create space for 128 partitions (or 32 sectors of 512 bytes).
83 utility to open the device for reading only.
84 Currently this option is primarily useful for the
86 command, but the intent
87 is to use it to implement dry-run behaviour.
91 option controls the verbosity level.
92 The level increases with every occurrence of this option.
93 There is no formalized definition of the different levels yet.
95 .Bl -tag -width indent
108 command allows the user to add a new partition to an existing table,
109 the name of the disk slice for the added partition is printed.
110 By default, it will create a
112 partition covering the first available block
113 of an unused disk space.
114 The command-specific options can be used to control this behaviour.
118 option allows the user to specify the starting (beginning) sector number of
120 The minimum sector number is 1, but has to fall inside an unused region of
121 disk space that is covered by the GPT.
125 option allows the user to specify which (free) entry in the GPT table is to
126 be used for the new partition.
127 By default, the first free entry is selected.
128 Entries start at index 0 representing partition 0 of the GPT.
132 option allows the user to specify the size of the partition in sectors.
133 The minimum size is 1.
137 option allows the user to specify the partition type.
138 The type is given as an UUID, but
141 .Cm efi , swap , ufs , hfs , linux , dfly ,
144 as aliases for the most commonly used partition types.
156 You may also specify any symbolic name in the system
160 .It Nm Ic boot Ar device ...
163 command allows the user to create a small boot partition in a freshly
166 This command creates a small, 768MB boot partition as partition #0
167 and hacks in a special
169 in the PMBR which aliases it.
170 The PMBR is further modified to add the necessary boot code.
171 You can then disklabel GPT partition #0 and mount it, placing the contents of
174 You must add a line to
177 .Bd -literal -offset indent
178 vfs.root.mountfrom="ufs:da1s1a"
181 which point to the actual root mount.
183 Your root partition may be another GPT partition and you may use a 64 bit
184 disklabel within that partition if you desire.
188 boot manager is used, it can be manipulated with the
192 option usually needs to be set.
195 A disk setup with the
197 command may not be shared with another OS,
198 as it doesn't use a fully standard GPT.
201 Some BIOSes may not be able to deal with this hack, your mileage may vary.
203 .It Nm Ic create Oo Fl fp Oc Ar device ...
206 command allows the user to create a new (empty) GPT.
207 By default, one cannot create a GPT when the device contains a MBR,
208 however this can be overridden with the
213 option is specified, an existing MBR is destroyed and any partitions
214 described by the MBR are lost.
220 to create only the primary table and not the backup table.
221 This option is only useful for debugging and should not be used otherwise.
222 .\" ==== destroy ====
223 .It Nm Ic destroy Oo Fl r Oc Ar device ...
226 command allows the user to destroy an existing, possibly not empty GPT.
232 to destroy the table in a way that it can be recovered.
238 .Aq Fl f Ar file | Fl l Ar label
248 .Aq Fl f Ar file | Fl l Ar label
253 command allows the user to label any partitions that match the selection.
254 At least one of the following selection options must be specified.
258 option specifies that all partitions should be labeled.
259 It is mutually exclusive with all other selection options.
263 option selects the partition that starts at the given block number.
267 option selects the partition with the given partition number.
268 Partition numbers start at 0.
272 option selects all partitions that have the given size.
273 This can cause multiple partitions to be removed.
277 option selects all partitions that have the given type.
278 The type is given as an UUID or by the aliases that the
281 This can cause multiple partitions to be removed.
287 options specify the new label to be assigned to the selected partitions.
290 option is used to read the label from the specified file.
291 Only the first line is read from the file and the trailing newline
292 character is stripped.
293 If the file name is the dash or minus sign
295 the label is read from
299 option is used to specify the label in the command line.
300 The label is assumed to be encoded in UTF-8.
301 .\" ==== migrate ====
302 .It Nm Ic migrate Oo Fl fs Oc Ar device ...
305 command allows the user to migrate an MBR-based disk partitioning into a
306 GPT-based partitioning.
307 By default, the MBR is not migrated when it contains partitions of an unknown
309 This can be overridden with the
314 option will cause unknown partitions to be ignored and any data in it
319 option prevents migrating
321 disk labels into GPT partitions by creating
322 the GPT equivalent of a slice.
324 .It Nm Ic remove Oo Fl a Oc Ar device ...
336 command allows the user to remove any and all partitions that match the
338 It uses the same selection options as the
341 See above for a description of these options.
342 Partitions are removed by clearing the partition type.
343 No other information is changed.
345 .It Nm Ic show Oo Fl lu Oc Ar device ...
348 command displays the current partitioning on the listed devices and gives
349 an overall view of the disk contents.
352 option the GPT partition label will be displayed instead of the GPT partition
354 The option has no effect on non-GPT partitions.
357 option the GPT partition type is displayed as an UUID instead of in a
361 option takes precedence over the
366 .Bl -tag -width ".Pa /etc/defaults/uuids"
371 .It Pa /etc/defaults/uuids
373 and their symbolic names provided by the OS vendor.
376 and their symbolic names provided by the system administrator.
379 To install an empty GPT on
384 GPT partitions are defined in number of sectors, the sector size is usually 512B,
385 which is assumed in the examples below, it can be found using:
387 .Dl "gpt -v show ad6"
389 To add a dummy GPT partition 0:
391 .Dl "gpt add -i0 -s16 ad6"
393 You might want to do this to not use slice 0 for data;
394 when GPT is not used on a disk, slice 0 is the compatibility slice,
396 .Dq dangerously dedicated
398 For GPT slice 0 has no special meaning, it is just the first slice on the disk.
400 To add a GPT partition of size approx. 100GB:
402 .Dl "gpt add -s200000000 ad6"
404 This will be GPT partition 1 as it is the first one free,
405 it will be accessible as
407 which is also printed by the command.
409 .Dq DragonFly Label64 ,
410 it will have to be set up by
413 To add GPT partition 5 with type
415 using the remaining free space:
416 .Bd -literal -offset indent
417 gpt add -i5 -t "DragonFly HAMMER" ad6
420 To print the contents of the GPT:
424 To setup a disk using GPT for booting, the steps below can be used.
425 System is copied from an already installed disk,
426 e.g.\& a hard disk or an install CD.
427 This example will setup disk
429 with GPT for booting, using the
434 Any previous data on disk installed to will be deleted.
435 .Bd -literal -offset indent
439 disklabel -B -r -w da1s0 auto
440 disklabel -e da1s0 # add `a: * * 4.2BSD', to add `a' partition
441 # with fstype `4.2BSD' covering whole slice
444 disklabel64 -r -w da1s1 auto
445 disklabel64 -e da1s1 # add `b: 4G * swap', to add `b' partition
446 # with fstype `swap' and size 4GB,
447 # add `a: * * HAMMER', to add `a' partition
448 # with fstype `HAMMER' covering rest of slice
449 newfs_hammer -L ROOT /dev/da1s1a
450 mount_hammer /dev/da1s1a /mnt
454 mount /dev/da1s0a /mnt/boot
456 cpdup / /mnt # copy each file system you need, e.g.
457 cpdup /boot /mnt/boot
459 cpdup /var/tmp /mnt/var/tmp
463 vi etc/fstab # add `/dev/da1s1a / hammer rw',
464 # add `/dev/da1s1b none swap sw',
465 # add `/dev/da1s0a /boot ufs rw 1 1',
466 # delete lines for file systems cpdup'ed above
467 vi boot/loader.conf # add `vfs.root.mountfrom="hammer:da1s1a"'
475 manipulates is part of the EFI standard and is supported by many OSs.
476 GPT uses 64 bits to store number of sectors, this supports very large disks.
477 With the prevalent sector size of 512B this is 8 billion TB.
499 The development of the
501 utility is still work in progress.
502 Many necessary features are missing or partially implemented.
503 In practice this means that the manual page, supposed to describe these
504 features, is farther removed from being complete or useful.
505 As such, missing functionality is not even documented as missing.
506 However, it is believed that the currently present functionality is reliable
507 and stable enough that this tool can be used without bullet-proof footware if
508 one thinks one does not make mistakes.
510 It is expected that the basic usage model does not change, but it is
511 possible that future versions will not be compatible in the strictest sense
515 option may be changed to a command option rather than a generic option.
516 There are only two commands that use it so there is a chance that the natural
517 tendency for people is to use it as a command option.
518 Also, options primarily intended for diagnostic or debug purposes may be
519 removed in future versions.
521 Another possibility is that the current usage model is accompanied by
522 other interfaces to make the tool usable as a back-end.
523 This all depends on demand and thus feedback.
527 command doesn't support
projects / dragonfly.git / blob