1 .\" Copyright (c) 2007, 2008 Marcel Moolenaar
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32 .Nd "control utility for the disk partitioning GEOM class"
34 To add support for the disk partitioning GEOM class,
35 place one or more of the following
36 lines in the kernel configuration file:
37 .Bd -ragged -offset indent
38 .Cd "options GEOM_PART_APM"
39 .Cd "options GEOM_PART_BSD"
40 .Cd "options GEOM_PART_GPT"
41 .Cd "options GEOM_PART_LDM"
42 .Cd "options GEOM_PART_MBR"
43 .Cd "options GEOM_PART_EBR"
44 .Cd "options GEOM_PART_EBR_COMPAT"
45 .Cd "options GEOM_PART_PC98"
46 .Cd "options GEOM_PART_VTOC8"
49 These options provide support for the various types of partitioning
50 schemes supported by the
54 .Sx "PARTITIONING SCHEMES"
55 below for more details.
76 .\" ==== BOOTCODE ====
80 .Op Fl p Ar partcode Fl i Ar index
100 .\" ==== DESTROY ====
114 .\" ==== RECOVER ====
123 .Op Fl a Ar alignment
127 .\" ==== RESTORE ====
162 utility is used to partition GEOM providers, normally disks.
163 The first argument is the action to be taken:
164 .Bl -tag -width ".Cm bootcode"
167 Add a new partition to the partitioning scheme given by
169 The partition begins on the logical block address given by the
172 Its size is given by the
175 SI unit suffixes are allowed.
180 options can be omitted.
181 If so they are automatically calculated.
182 The type of the partition is given by the
185 Partition types are discussed below in the section entitled
186 .Sx "PARTITION TYPES" .
188 Additional options include:
190 .It Fl a Ar alignment
193 utility tries to align
201 The index in the partition table at which the new partition is to be
203 The index determines the name of the device special file used
204 to represent the partition.
206 The label attached to the partition.
207 This option is only valid when used on partitioning schemes that support
210 Additional operational flags.
211 See the section entitled
212 .Sx "OPERATIONAL FLAGS"
213 below for a discussion
218 Dump a partition table to standard output in a special format used by the
221 .\" ==== BOOTCODE ====
223 Embed bootstrap code into the partitioning scheme's metadata on the
227 or write bootstrap code into a partition (using
231 Not all partitioning schemes have embedded bootstrap code, so the
233 option is scheme-specific in nature (see the section entitled
238 option specifies a file that contains the bootstrap code.
239 The contents and size of the file are determined by the partitioning
243 option specifies a file that contains the bootstrap code intended to be
244 written to a partition.
245 The partition is specified by the
248 The size of the file must be smaller than the size of the partition.
250 Additional options include:
253 Additional operational flags.
254 See the section entitled
255 .Sx "OPERATIONAL FLAGS"
256 below for a discussion
261 Commit any pending changes for geom
263 All actions are committed by default and will not result in
265 Actions can be modified with the
267 option so that they are not committed, but become pending.
268 Pending changes are reflected by the geom and the
270 utility, but they are not actually written to disk.
273 action will write all pending changes to disk.
276 Create a new partitioning scheme on a provider given by
280 option determines the scheme to use.
281 The kernel must have support for a particular scheme before
282 that scheme can be used to partition a disk.
284 Additional options include:
287 The number of entries in the partition table.
288 Every partitioning scheme has a minimum and maximum number of entries.
289 This option allows tables to be created with a number of entries
290 that is within the limits.
291 Some schemes have a maximum equal to the minimum and some schemes have
292 a maximum large enough to be considered unlimited.
293 By default, partition tables are created with the minimum number of
296 Additional operational flags.
297 See the section entitled
298 .Sx "OPERATIONAL FLAGS"
299 below for a discussion
304 Delete a partition from geom
306 and further identified by the
309 The partition cannot be actively used by the kernel.
311 Additional options include:
314 Additional operational flags.
315 See the section entitled
316 .Sx "OPERATIONAL FLAGS"
317 below for a discussion
320 .\" ==== DESTROY ====
322 Destroy the partitioning scheme as implemented by geom
325 Additional options include:
328 Forced destroying of the partition table even if it is not empty.
330 Additional operational flags.
331 See the section entitled
332 .Sx "OPERATIONAL FLAGS"
333 below for a discussion
338 Modify a partition from geom
340 and further identified by the
343 Only the type and/or label of the partition can be modified.
344 To change the type of a partition, specify the new type with the
347 To change the label of a partition, specify the new label with the
350 Not all partitioning schemes support labels and it is invalid to
351 try to change a partition label in such cases.
353 Additional options include:
356 Additional operational flags.
357 See the section entitled
358 .Sx "OPERATIONAL FLAGS"
359 below for a discussion
362 .\" ==== RECOVER ====
364 Recover a corrupt partition's scheme metadata on the geom
366 See the section entitled
368 below for the additional information.
370 Additional options include:
373 Additional operational flags.
374 See the section entitled
375 .Sx "OPERATIONAL FLAGS"
376 below for a discussion
381 Resize a partition from geom
383 and further identified by the
386 New partition size is expressed in logical block
387 numbers and can be given by the
392 option is omitted then new size is automatically calculated
393 to maximum available from given geom
396 Additional options include:
398 .It Fl a Ar alignment
401 utility tries to align partition
407 Additional operational flags.
408 See the section entitled
409 .Sx "OPERATIONAL FLAGS"
410 below for a discussion
413 .\" ==== RESTORE ====
415 Restore the partition table from a backup previously created by the
417 action and read from standard input.
418 Only the partition table is restored.
419 This action does not affect the content of partitions.
420 After restoring the partition table and writing bootcode if needed,
421 user data must be restored from backup.
423 Additional options include:
426 Destroy partition table on the given
428 before doing restore.
430 Restore partition labels for partitioning schemes that support them.
432 Additional operational flags.
433 See the section entitled
434 .Sx "OPERATIONAL FLAGS"
435 below for a discussion
440 Set the named attribute on the partition entry.
441 See the section entitled
443 below for a list of available attributes.
445 Additional options include:
448 Additional operational flags.
449 See the section entitled
450 .Sx "OPERATIONAL FLAGS"
451 below for a discussion
456 Show the current partition information of the specified geoms
457 or all geoms if none are specified.
458 Additional options include:
461 For partitioning schemes that support partition labels, print them
462 instead of partition type.
464 Show provider names instead of partition indexes.
466 Show raw partition type instead of symbolic name.
470 Revert any pending changes for geom
472 This action is the opposite of the
474 action and can be used to undo any changes that have not been committed.
477 Clear the named attribute on the partition entry.
478 See the section entitled
480 below for a list of available attributes.
482 Additional options include:
485 Additional operational flags.
486 See the section entitled
487 .Sx "OPERATIONAL FLAGS"
488 below for a discussion
492 .Sh PARTITIONING SCHEMES
493 Several partitioning schemes are supported by the
496 .Bl -tag -width ".Cm VTOC8"
498 Apple Partition Map, used by PowerPC(R) Macintosh(R) computers.
503 Traditional BSD disklabel, usually used to subdivide MBR partitions.
505 This scheme can also be used as the sole partitioning method, without
507 Partition editing tools from other operating systems often do not
508 understand the bare disklabel partition layout, so this is sometimes
510 .Dq dangerously dedicated .
516 The Logical Disk Manager is an implementation of volume manager for
517 Microsoft Windows NT.
522 GUID Partition Table is used on Intel-based Macintosh computers and
523 gradually replacing MBR on most PCs and other systems.
528 Master Boot Record is used on PCs and removable media.
534 option adds support for the Extended Boot Record (EBR),
535 which is used to define a logical partition.
537 .Cm GEOM_PART_EBR_COMPAT
538 option enables backward compatibility for partition names
540 It also prevents any type of actions on such partitions.
542 An MBR variant for NEC PC-98 and compatible computers.
547 Sun's SMI Volume Table Of Contents, used by
557 Partition types are identified on disk by particular strings or magic
561 utility uses symbolic names for common partition types so the user
562 does not need to know these values or other details of the partitioning
566 utility also allows the user to specify scheme-specific partition types
567 for partition types that do not have symbolic names.
568 Symbolic names currently understood are:
569 .Bl -tag -width ".Cm ms-ldm-metadata"
571 The system partition dedicated to second stage of the boot loader program.
572 Usually it is used by the GRUB 2 loader for GPT partitioning schemes.
573 The scheme-specific type is
574 .Qq Li "!21686148-6449-6E6F-744E-656564454649" .
576 The system partition for computers that use the Extensible Firmware
578 In such cases, the GPT partitioning scheme is used and the
579 actual partition type for the system partition can also be specified as
580 .Qq Li "!c12a7328-f81f-11d2-ba4b-00a0c93ec93ab" .
584 partition subdivided into filesystems with a
587 This is a legacy partition type and should not be used for the APM
589 The scheme-specific types are
594 .Qq Li "!516e7cb4-6ecf-11d6-8ff8-00022d09712b"
599 partition dedicated to bootstrap code.
600 The scheme-specific type is
601 .Qq Li "!83bd6b9d-7f41-11dc-be0b-001560b84f0f"
606 partition dedicated to swap space.
607 The scheme-specific types are
608 .Qq Li "!FreeBSD-swap"
610 .Qq Li "!516e7cb5-6ecf-11d6-8ff8-00022d09712b"
611 for GPT, and tag 0x0901 for VTOC8.
615 partition that contains a UFS or UFS2 filesystem.
616 The scheme-specific types are
617 .Qq Li "!FreeBSD-UFS"
619 .Qq Li "!516e7cb6-6ecf-11d6-8ff8-00022d09712b"
620 for GPT, and tag 0x0902 for VTOC8.
624 partition that contains a Vinum volume.
625 The scheme-specific types are
626 .Qq Li "!FreeBSD-Vinum"
628 .Qq Li "!516e7cb8-6ecf-11d6-8ff8-00022d09712b"
629 for GPT, and tag 0x0903 for VTOC8.
633 partition that contains a ZFS volume.
634 The scheme-specific types are
635 .Qq Li "!FreeBSD-ZFS"
637 .Qq Li "!516e7cba-6ecf-11d6-8ff8-00022d09712b"
638 for GPT, and 0x0904 for VTOC8.
640 A partition that is sub-partitioned by a Master Boot Record (MBR).
641 This type is known as
642 .Qq Li "!024dee41-33e7-11d3-9d69-0008c781f39f"
645 A partition that contains Logical Disk Manager (LDM) volumes.
646 The scheme-specific types are
649 .Qq Li "!af9b60a0-1431-4f62-bc68-3311714a69ad"
651 .It Cm ms-ldm-metadata
652 A partition that contains Logical Disk Manager (LDM) database.
653 The scheme-specific type is
654 .Qq Li "!5808c8aa-7e8f-42e0-85d2-e1e90434cfb3"
658 The scheme-specific attributes for EBR:
659 .Bl -tag -width ".Cm active"
663 The scheme-specific attributes for GPT:
664 .Bl -tag -width ".Cm bootfailed"
668 stage 1 boot loader will try to boot the system from this partition.
669 Multiple partitions might be marked with the
676 partitions one by one, until the next boot stage is successfully entered.
678 Setting this attribute automatically sets the
683 stage 1 boot loader will try to boot the system from this partition only once.
688 attributes are tried before partitions with only the
693 partition is tried, the
697 attribute and tries to execute the next boot stage.
700 attribute that is now alone is replaced with the
703 If the execution of the next boot stage succeeds, but the system is not fully
708 attributes alone (without the
710 attribute) on the next system boot and will replace those with the
713 If the system is fully booted, the
714 .Pa /etc/rc.d/gptboot
715 start-up script will look for partition with the
717 attribute alone, will remove the attribute and log that the system was
718 successfully booted from this partition.
719 There should be at most one
721 partition when system is successfully booted.
722 Multiple partitions might be marked with the
728 This attribute should not be manually managed.
731 stage 1 boot loader and the
732 .Pa /etc/rc.d/gptboot
734 This attribute is used to mark partitions that had the
736 attribute set, but we failed to boot from them.
737 Once we successfully boot, the
738 .Pa /etc/rc.d/gptboot
739 script will log all the partitions we failed to boot from and will remove the
744 The scheme-specific attributes for MBR:
745 .Bl -tag -width ".Cm active"
749 The scheme-specific attributes for PC98:
750 .Bl -tag -width ".Cm bootable"
756 supports several partitioning schemes and each scheme uses different
758 The bootstrap code is located in a specific disk area for each partitioning
759 scheme, and may vary in size for different schemes.
761 Bootstrap code can be separated into two types.
762 The first type is embedded in the partitioning scheme's metadata, while the
763 second type is located on a specific partition.
764 Embedding bootstrap code should only be done with the
769 The GEOM PART class knows how to safely embed bootstrap code into
770 specific partitioning scheme metadata without causing any damage.
772 The Master Boot Record (MBR) uses a 512-byte bootstrap code image, embedded
773 into the partition table's metadata area.
774 There are two variants of this bootstrap code:
779 searches for a partition with the
783 section) in the partition table.
784 Then it runs next bootstrap stage.
787 image contains a boot manager with some additional interactive functions
788 for multi-booting from a user-selected partition.
790 A BSD disklabel is usually created inside an MBR partition (slice)
794 .Sx "PARTITION TYPES"
796 It uses 8 KB size bootstrap code image
798 embedded into the partition table's metadata area.
800 Both types of bootstrap code are used to boot from the GUID Partition Table.
801 First, a protective MBR is embedded into the first disk sector from the
807 .Sx "PARTITION TYPES"
808 section) in the GPT and runs the next bootstrap stage from it.
811 partition should be smaller than 545 KB.
812 There are two variants of bootstrap code to write to this partition:
815 .Pa /boot/gptzfsboot .
817 is used to boot from UFS.
820 GPT partitions and starts
822 .Pq the third bootstrap stage
826 is used to boot from ZFS.
829 GPT partitions and starts
833 The VTOC8 scheme does not support embedding bootstrap code.
834 Instead, the 8 KBytes bootstrap code image
836 should be written with the
840 option to all sufficiently large VTOC8 partitions.
843 option could be omitted.
845 The APM scheme also does not support embedding bootstrap code.
846 Instead, the 800 KBytes bootstrap code image
848 should be written with the
850 command to a partition of type
852 which should also be 800 KB in size.
853 .Sh OPERATIONAL FLAGS
854 Actions other than the
858 actions take an optional
861 This option is used to specify action-specific operational flags.
866 flag so that the action is immediately
870 to have the action result in a pending change that can later, with
871 other pending changes, be committed as a single compound change with
874 action or reverted with the
878 The GEOM PART class supports recovering of partition tables only for GPT.
879 The GPT primary metadata is stored at the beginning of the device.
880 For redundancy, a secondary
882 copy of the metadata is stored at the end of the device.
883 As a result of having two copies, some corruption of metadata is not
884 fatal to the working of GPT.
885 When the kernel detects corrupt metadata, it marks this table as corrupt
886 and reports the problem.
890 are the only operations allowed on corrupt tables.
892 If the first sector of a provider is corrupt, the kernel can not detect GPT
893 even if the partition table itself is not corrupt.
894 The protective MBR can be rewritten using the
896 command, to restore the ability to detect the GPT.
897 The copy of the protective MBR is usually located in the
901 If one GPT header appears to be corrupt but the other copy remains intact,
902 the kernel will log the following:
903 .Bd -literal -offset indent
904 GEOM: provider: the primary GPT table is corrupt or invalid.
905 GEOM: provider: using the secondary instead -- recovery strongly advised.
909 .Bd -literal -offset indent
910 GEOM: provider: the secondary GPT table is corrupt or invalid.
911 GEOM: provider: using the primary only -- recovery suggested.
920 will report about corrupt tables.
922 If the size of the device has changed (e.g.\& volume expansion) the
923 secondary GPT header will no longer be located in the last sector.
924 This is not a metadata corruption, but it is dangerous because any
925 corruption of the primary GPT will lead to loss of the partition table.
926 This problem is reported by the kernel with the message:
927 .Bd -literal -offset indent
928 GEOM: provider: the secondary GPT header is not in the last LBA.
931 This situation can be recovered with the
934 This command reconstructs the corrupt metadata using known valid
935 metadata and relocates the secondary GPT to the end of the device.
938 The GEOM PART class can detect the same partition table visible through
939 different GEOM providers, and some of them will be marked as corrupt.
940 Be careful when choosing a provider for recovery.
941 If you choose incorrectly you can destroy the metadata of another GEOM class,
942 e.g.\& GEOM MIRROR or GEOM LABEL.
946 variables can be used to control the behavior of the
949 The default value is shown next to each variable.
950 .Bl -tag -width indent
951 .It Va kern.geom.part.check_integrity : No 1
952 This variable controls the behaviour of metadata integrity checks.
953 When integrity checks are enabled, the
955 GEOM class verifies all generic partition parameters obtained from the
957 If some inconsistency is detected, the partition table will be
958 rejected with a diagnostic message:
959 .Sy "GEOM_PART: Integrity check failed (provider, scheme)" .
960 .It Va kern.geom.part.ldm.debug : No 0
961 Debug level of the Logical Disk Manager (LDM) module.
962 This can be set to a number between 0 and 2 inclusive.
963 If set to 0 minimal debug information is printed,
964 and if set to 2 the maximum amount of debug information is printed.
965 .It Va kern.geom.part.ldm.show_mirrors : No 0
966 This variable controls how the Logical Disk Manager (LDM) module handles
968 By default mirrored volumes are shown as partitions with type
971 .Sx "PARTITION TYPES"
973 If this variable set to 1 each component of the mirrored volume will be
974 present as independent partition.
976 This may break a mirrored volume and lead to data damage.
979 Exit status is 0 on success, and 1 if the command fails.
981 Create a GPT scheme on
983 .Bd -literal -offset indent
984 /sbin/gpart create -s GPT ad0
987 Embed GPT bootstrap code into a protective MBR:
988 .Bd -literal -offset indent
989 /sbin/gpart bootcode -b /boot/pmbr ad0
994 partition that can boot
998 partition, and install bootstrap code into it.
999 This partition must be larger than the bootstrap code
1004 .Pa /boot/gptzfsboot
1006 but smaller than 545 kB since the first-stage loader will load the
1007 entire partition into memory during boot, regardless of how much data
1008 it actually contains.
1009 This example uses 88 blocks (44 kB) so the next partition will be
1010 aligned on a 64 kB boundary without the need to specify an explicit
1011 offset or alignment.
1012 The boot partition itself is aligned on a 4 kB boundary.
1013 .Bd -literal -offset indent
1014 /sbin/gpart add -b 40 -s 88 -t freebsd-boot ad0
1015 /sbin/gpart bootcode -p /boot/gptboot -i 1 ad0
1018 Create a 512MB-sized
1020 partition to contain a UFS filesystem from which the system can boot.
1021 .Bd -literal -offset indent
1022 /sbin/gpart add -s 512M -t freebsd-ufs ad0
1025 Create an MBR scheme on
1027 then create a 30GB-sized
1029 slice, mark it active and
1033 .Bd -literal -offset indent
1034 /sbin/gpart create -s MBR ada0
1035 /sbin/gpart add -t freebsd -s 30G ada0
1036 /sbin/gpart set -a active -i 1 ada0
1037 /sbin/gpart bootcode -b /boot/boot0 ada0
1044 label) with space for up to 20 partitions:
1045 .Bd -literal -offset indent
1046 /sbin/gpart create -s BSD -n 20 ada0s1
1049 Create a 1GB-sized UFS partition and a 4GB-sized swap partition:
1050 .Bd -literal -offset indent
1051 /sbin/gpart add -t freebsd-ufs -s 1G ada0s1
1052 /sbin/gpart add -t freebsd-swap -s 4G ada0s1
1055 Install bootstrap code for the
1058 .Bd -literal -offset indent
1059 /sbin/gpart bootcode -b /boot/boot ada0s1
1062 Create a VTOC8 scheme on
1064 .Bd -literal -offset indent
1065 /sbin/gpart create -s VTOC8 da0
1068 Create a 512MB-sized
1070 partition to contain a UFS filesystem from which the system can boot.
1071 .Bd -literal -offset indent
1072 /sbin/gpart add -s 512M -t freebsd-ufs da0
1077 partition to contain a UFS filesystem and aligned on 4KB boundaries:
1078 .Bd -literal -offset indent
1079 /sbin/gpart add -s 15G -t freebsd-ufs -a 4k da0
1082 After creating all required partitions, embed bootstrap code into them:
1083 .Bd -literal -offset indent
1084 /sbin/gpart bootcode -p /boot/boot1 da0
1087 Create a backup of the partition table from
1089 .Bd -literal -offset indent
1090 /sbin/gpart backup da0 > da0.backup
1093 Restore the partition table from the backup to
1095 .Bd -literal -offset indent
1096 /sbin/gpart restore -l da0 < /mnt/da0.backup
1099 Clone the partition table from
1105 .Bd -literal -offset indent
1106 /sbin/gpart backup ada0 | /sbin/gpart restore -F ada1 ada2
1119 .An Marcel Moolenaar Aq marcel@FreeBSD.org