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32 .Nd "control utility for the disk partitioning GEOM class"
49 .\" ==== BOOTCODE ====
54 .Op Fl p Ar partcode Fl i Ar index
101 .\" ==== RESTORE ====
144 utility is used to partition GEOM providers, normally disks.
145 The first argument is the action to be taken:
146 .Bl -tag -width ".Cm bootcode"
149 Add a new partition to the partitioning scheme given by
151 The partition type must be specified with
153 The partition's location, size, and other attributes will be calculated
154 automatically if the corresponding options are not specified.
158 command accepts these options:
160 .It Fl a Ar alignment
163 utility tries to align
171 The logical block address where the partition will begin.
172 A SI unit suffix is allowed.
174 Additional operational flags.
175 See the section entitled
176 .Sx "OPERATIONAL FLAGS"
177 below for a discussion
180 The index in the partition table at which the new partition is to be
182 The index determines the name of the device special file used
183 to represent the partition.
185 The label attached to the partition.
186 This option is only valid when used on partitioning schemes that support
189 Create a partition of size
191 A SI unit suffix is allowed.
193 Create a partition of type
195 Partition types are discussed below in the section entitled
196 .Sx "PARTITION TYPES" .
200 Dump a partition table to standard output in a special format used by the
203 .\" ==== BOOTCODE ====
205 Embed bootstrap code into the partitioning scheme's metadata on the
209 or write bootstrap code into a partition (using
216 command accepts these options:
219 Don't preserve the Volume Serial Number for MBR.
220 MBR bootcode contains Volume Serial Number by default, and
222 tries to preserve it when installing new bootstrap code.
223 This option allows to skip the preservation to help with some versions of
225 that don't support Volume Serial Number.
227 Embed bootstrap code from the file
229 into the partitioning scheme's metadata for
231 Not all partitioning schemes have embedded bootstrap code, so the
233 option is scheme-specific in nature (see the section entitled
238 file must match the partitioning scheme's requirements for file content
241 Additional operational flags.
242 See the section entitled
243 .Sx "OPERATIONAL FLAGS"
244 below for a discussion
247 Specify the target partition for
250 Write the bootstrap code from the file
254 partition specified by
256 The size of the file must be smaller than the size of the partition.
260 Commit any pending changes for geom
262 All actions are committed by default and will not result in
264 Actions can be modified with the
266 option so that they are not committed, but become pending.
267 Pending changes are reflected by the geom and the
269 utility, but they are not actually written to disk.
272 action will write all pending changes to disk.
275 Create a new partitioning scheme on a provider given by
277 The scheme to use must be specified with the
283 command accepts these options:
286 Additional operational flags.
287 See the section entitled
288 .Sx "OPERATIONAL FLAGS"
289 below for a discussion
292 The number of entries in the partition table.
293 Every partitioning scheme has a minimum and maximum number of entries.
294 This option allows tables to be created with a number of entries
295 that is within the limits.
296 Some schemes have a maximum equal to the minimum and some schemes have
297 a maximum large enough to be considered unlimited.
298 By default, partition tables are created with the minimum number of
301 Specify the partitioning scheme to use.
302 The kernel must have support for a particular scheme before
303 that scheme can be used to partition a disk.
307 Delete a partition from geom
309 and further identified by the
312 The partition cannot be actively used by the kernel.
316 command accepts these options:
319 Additional operational flags.
320 See the section entitled
321 .Sx "OPERATIONAL FLAGS"
322 below for a discussion
325 Specifies the index of the partition to be deleted.
327 .\" ==== DESTROY ====
329 Destroy the partitioning scheme as implemented by geom
334 command accepts these options:
337 Forced destroying of the partition table even if it is not empty.
339 Additional operational flags.
340 See the section entitled
341 .Sx "OPERATIONAL FLAGS"
342 below for a discussion
347 Modify a partition from geom
349 and further identified by the
352 Only the type and/or label of the partition can be modified.
353 Not all partitioning schemes support labels and it is invalid to
354 try to change a partition label in such cases.
358 command accepts these options:
361 Additional operational flags.
362 See the section entitled
363 .Sx "OPERATIONAL FLAGS"
364 below for a discussion
367 Specifies the index of the partition to be modified.
369 Change the partition label to
372 Change the partition type to
375 .\" ==== RECOVER ====
377 Recover a corrupt partition's scheme metadata on the geom
379 See the section entitled
381 below for the additional information.
385 command accepts these options:
388 Additional operational flags.
389 See the section entitled
390 .Sx "OPERATIONAL FLAGS"
391 below for a discussion
396 Resize a partition from geom
398 and further identified by the
401 If the new size is not specified it is automatically calculated
402 to be the maximum available from
407 command accepts these options:
409 .It Fl a Ar alignment
412 utility tries to align partition
414 to be a multiple of the
418 Additional operational flags.
419 See the section entitled
420 .Sx "OPERATIONAL FLAGS"
421 below for a discussion
424 Specifies the index of the partition to be resized.
426 Specifies the new size of the partition, in logical blocks.
427 A SI unit suffix is allowed.
429 .\" ==== RESTORE ====
431 Restore the partition table from a backup previously created by the
433 action and read from standard input.
434 Only the partition table is restored.
435 This action does not affect the content of partitions.
436 After restoring the partition table and writing bootcode if needed,
437 user data must be restored from backup.
441 command accepts these options:
444 Destroy partition table on the given
446 before doing restore.
448 Additional operational flags.
449 See the section entitled
450 .Sx "OPERATIONAL FLAGS"
451 below for a discussion
454 Restore partition labels for partitioning schemes that support them.
458 Set the named attribute on the partition entry.
459 See the section entitled
461 below for a list of available attributes.
465 command accepts these options:
468 Specifies the attribute to set.
470 Additional operational flags.
471 See the section entitled
472 .Sx "OPERATIONAL FLAGS"
473 below for a discussion
476 Specifies the index of the partition on which the attribute will be set.
480 Show current partition information for the specified geoms, or all
481 geoms if none are specified.
482 The default output includes the logical starting block of each
483 partition, the partition size in blocks, the partition index number,
484 the partition type, and a human readable partition size.
485 Block sizes and locations are based on the device's Sectorsize
491 command accepts these options:
494 For partitioning schemes that support partition labels, print them
495 instead of partition type.
497 Show provider names instead of partition indexes.
499 Show raw partition type instead of symbolic name.
503 Revert any pending changes for geom
505 This action is the opposite of the
507 action and can be used to undo any changes that have not been committed.
510 Clear the named attribute on the partition entry.
511 See the section entitled
513 below for a list of available attributes.
517 command accepts these options:
520 Specifies the attribute to clear.
522 Additional operational flags.
523 See the section entitled
524 .Sx "OPERATIONAL FLAGS"
525 below for a discussion
528 Specifies the index of the partition on which the attribute will be cleared.
543 .Sh PARTITIONING SCHEMES
544 Several partitioning schemes are supported by the
547 .Bl -tag -width ".Cm VTOC8"
549 Apple Partition Map, used by PowerPC(R) Macintosh(R) computers.
554 Traditional BSD disklabel, usually used to subdivide MBR partitions.
556 This scheme can also be used as the sole partitioning method, without
558 Partition editing tools from other operating systems often do not
559 understand the bare disklabel partition layout, so this is sometimes
561 .Dq dangerously dedicated .
567 64-bit implementation of BSD disklabel used in DragonFlyBSD to subdivide MBR
573 The Logical Disk Manager is an implementation of volume manager for
574 Microsoft Windows NT.
579 GUID Partition Table is used on Intel-based Macintosh computers and
580 gradually replacing MBR on most PCs and other systems.
585 Master Boot Record is used on PCs and removable media.
591 option adds support for the Extended Boot Record (EBR),
592 which is used to define a logical partition.
594 .Cm GEOM_PART_EBR_COMPAT
595 option enables backward compatibility for partition names
597 It also prevents any type of actions on such partitions.
599 Sun's SMI Volume Table Of Contents, used by
609 Partition types are identified on disk by particular strings or magic
613 utility uses symbolic names for common partition types so the user
614 does not need to know these values or other details of the partitioning
618 utility also allows the user to specify scheme-specific partition types
619 for partition types that do not have symbolic names.
620 Symbolic names currently understood and used by
623 .Bl -tag -width ".Cm dragonfly-disklabel64"
625 The system partition dedicated to storing boot loaders on some Apple
627 The scheme-specific types are
630 .Qq Li "!Apple_Bootstrap"
632 .Qq Li "!426f6f74-0000-11aa-aa11-00306543ecac"
635 The system partition dedicated to second stage of the boot loader program.
636 Usually it is used by the GRUB 2 loader for GPT partitioning schemes.
637 The scheme-specific type is
638 .Qq Li "!21686148-6449-6E6F-744E-656564454649" .
640 The system partition for computers that use the Extensible Firmware
642 The scheme-specific types are
645 .Qq Li "!c12a7328-f81f-11d2-ba4b-00a0c93ec93b"
650 partition subdivided into filesystems with a
653 This is a legacy partition type and should not be used for the APM
655 The scheme-specific types are
660 .Qq Li "!516e7cb4-6ecf-11d6-8ff8-00022d09712b"
665 partition dedicated to bootstrap code.
666 The scheme-specific type is
667 .Qq Li "!83bd6b9d-7f41-11dc-be0b-001560b84f0f"
672 partition dedicated to swap space.
673 The scheme-specific types are
674 .Qq Li "!FreeBSD-swap"
676 .Qq Li "!516e7cb5-6ecf-11d6-8ff8-00022d09712b"
677 for GPT, and tag 0x0901 for VTOC8.
681 partition that contains a UFS or UFS2 filesystem.
682 The scheme-specific types are
683 .Qq Li "!FreeBSD-UFS"
685 .Qq Li "!516e7cb6-6ecf-11d6-8ff8-00022d09712b"
686 for GPT, and tag 0x0902 for VTOC8.
690 partition that contains a Vinum volume.
691 The scheme-specific types are
692 .Qq Li "!FreeBSD-Vinum"
694 .Qq Li "!516e7cb8-6ecf-11d6-8ff8-00022d09712b"
695 for GPT, and tag 0x0903 for VTOC8.
699 partition that contains a ZFS volume.
700 The scheme-specific types are
701 .Qq Li "!FreeBSD-ZFS"
703 .Qq Li "!516e7cba-6ecf-11d6-8ff8-00022d09712b"
704 for GPT, and 0x0904 for VTOC8.
707 Another symbolic names that can be used with
710 .Bl -tag -width ".Cm dragonfly-disklabel64"
712 An Apple macOS partition used for the Apple file system, APFS.
713 .It Cm apple-core-storage
714 An Apple Mac OS X partition used by logical volume manager known as
716 The scheme-specific type is
717 .Qq Li "!53746f72-6167-11aa-aa11-00306543ecac"
720 An Apple Mac OS X partition that contains a HFS or HFS+ filesystem.
721 The scheme-specific types are
726 .Qq Li "!48465300-0000-11aa-aa11-00306543ecac"
729 An Apple Mac OS X partition dedicated to partition metadata that descibes
731 The scheme-specific type is
732 .Qq Li "!4c616265-6c00-11aa-aa11-00306543ecac"
735 An Apple Mac OS X partition used in a software RAID configuration.
736 The scheme-specific type is
737 .Qq Li "!52414944-0000-11aa-aa11-00306543ecac"
739 .It Cm apple-raid-offline
740 An Apple Mac OS X partition used in a software RAID configuration.
741 The scheme-specific type is
742 .Qq Li "!52414944-5f4f-11aa-aa11-00306543ecac"
744 .It Cm apple-tv-recovery
745 An Apple Mac OS X partition used by Apple TV.
746 The scheme-specific type is
747 .Qq Li "!5265636f-7665-11aa-aa11-00306543ecac"
750 An Apple Mac OS X partition that contains a UFS filesystem.
751 The scheme-specific types are
754 .Qq Li "!Apple_UNIX_SVR2"
756 .Qq Li "!55465300-0000-11aa-aa11-00306543ecac"
758 .It Cm dragonfly-label32
759 A DragonFlyBSD partition subdivided into filesystems with a
762 The scheme-specific type is
763 .Qq Li "!9d087404-1ca5-11dc-8817-01301bb8a9f5"
765 .It Cm dragonfly-label64
766 A DragonFlyBSD partition subdivided into filesystems with a
768 The scheme-specific type is
769 .Qq Li "!3d48ce54-1d16-11dc-8696-01301bb8a9f5"
771 .It Cm dragonfly-legacy
772 A legacy partition type used in DragonFlyBSD.
773 The scheme-specific type is
774 .Qq Li "!bd215ab2-1d16-11dc-8696-01301bb8a9f5"
777 A DragonFlyBSD partition used with Concatenated Disk driver.
778 The scheme-specific type is
779 .Qq Li "!dbd5211b-1ca5-11dc-8817-01301bb8a9f5"
781 .It Cm dragonfly-hammer
782 A DragonFlyBSD partition that contains a Hammer filesystem.
783 The scheme-specific type is
784 .Qq Li "!61dc63ac-6e38-11dc-8513-01301bb8a9f5"
786 .It Cm dragonfly-hammer2
787 A DragonFlyBSD partition that contains a Hammer2 filesystem.
788 The scheme-specific type is
789 .Qq Li "!5cbb9ad1-862d-11dc-a94d-01301bb8a9f5"
791 .It Cm dragonfly-swap
792 A DragonFlyBSD partition dedicated to swap space.
793 The scheme-specific type is
794 .Qq Li "!9d58fdbd-1ca5-11dc-8817-01301bb8a9f5"
797 A DragonFlyBSD partition that contains an UFS1 filesystem.
798 The scheme-specific type is
799 .Qq Li "!9d94ce7c-1ca5-11dc-8817-01301bb8a9f5"
801 .It Cm dragonfly-vinum
802 A DragonFlyBSD partition used with Logical Volume Manager.
803 The scheme-specific type is
804 .Qq Li "!9dd4478f-1ca5-11dc-8817-01301bb8a9f5"
807 A partition subdivided into filesystems with a EBR.
808 The scheme-specific type is
812 A partition that contains a FAT16 filesystem.
813 The scheme-specific type is
817 A partition that contains a FAT32 filesystem.
818 The scheme-specific type is
822 A partition that contains a FAT32 (LBA) filesystem.
823 The scheme-specific type is
827 A Linux partition that contains some filesystem with data.
828 The scheme-specific types are
831 .Qq Li "!0fc63daf-8483-4772-8e79-3d69d8477de4"
834 A Linux partition dedicated to Logical Volume Manager.
835 The scheme-specific types are
838 .Qq Li "!e6d6d379-f507-44c2-a23c-238f2a3df928"
841 A Linux partition used in a software RAID configuration.
842 The scheme-specific types are
845 .Qq Li "!a19d880f-05fc-4d3b-a006-743f0f84911e"
848 A Linux partition dedicated to swap space.
849 The scheme-specific types are
852 .Qq Li "!0657fd6d-a4ab-43c4-84e5-0933c84b4f4f"
855 A partition that is sub-partitioned by a Master Boot Record (MBR).
856 This type is known as
857 .Qq Li "!024dee41-33e7-11d3-9d69-0008c781f39f"
860 A basic data partition (BDP) for Microsoft operating systems.
861 In the GPT this type is the equivalent to partition types
866 The scheme-specific type is
867 .Qq Li "!ebd0a0a2-b9e5-4433-87c0-68b6b72699c7"
870 A partition that contains Logical Disk Manager (LDM) volumes.
871 The scheme-specific types are
874 .Qq Li "!af9b60a0-1431-4f62-bc68-3311714a69ad"
876 .It Cm ms-ldm-metadata
877 A partition that contains Logical Disk Manager (LDM) database.
878 The scheme-specific type is
879 .Qq Li "!5808c8aa-7e8f-42e0-85d2-e1e90434cfb3"
882 A NetBSD partition used with Concatenated Disk driver.
883 The scheme-specific type is
884 .Qq Li "!2db519c4-b10f-11dc-b99b-0019d1879648"
887 An encrypted NetBSD partition.
888 The scheme-specific type is
889 .Qq Li "!2db519ec-b10f-11dc-b99b-0019d1879648"
892 A NetBSD partition that contains an UFS filesystem.
893 The scheme-specific type is
894 .Qq Li "!49f48d5a-b10e-11dc-b99b-0019d1879648"
897 A NetBSD partition that contains an LFS filesystem.
898 The scheme-specific type is
899 .Qq Li "!49f48d82-b10e-11dc-b99b-0019d1879648"
902 A NetBSD partition used in a software RAID configuration.
903 The scheme-specific type is
904 .Qq Li "!49f48daa-b10e-11dc-b99b-0019d1879648"
907 A NetBSD partition dedicated to swap space.
908 The scheme-specific type is
909 .Qq Li "!49f48d32-b10e-11dc-b99b-0019d1879648"
912 A partition that contains a NTFS or exFAT filesystem.
913 The scheme-specific type is
917 The system partition dedicated to storing boot loaders on some PowerPC systems,
918 notably those made by IBM.
919 The scheme-specific types are
922 .Qq Li "!0x9e1a2d38-c612-4316-aa26-8b49521e5a8b"
925 A partition that contains a VMware File System (VMFS).
926 The scheme-specific types are
929 .Qq Li "!aa31e02a-400f-11db-9590-000c2911d1b8"
931 .It Cm vmware-vmkdiag
932 A partition that contains a VMware diagostic filesystem.
933 The scheme-specific types are
936 .Qq Li "!9d275380-40ad-11db-bf97-000c2911d1b8"
938 .It Cm vmware-reserved
939 A VMware reserved partition.
940 The scheme-specific type is
941 .Qq Li "!9198effc-31c0-11db-8f-78-000c2911d1b8"
943 .It Cm vmware-vsanhdr
944 A partition claimed by VMware VSAN.
945 The scheme-specific type is
946 .Qq Li "!381cfccc-7288-11e0-92ee-000c2911d0b2"
950 The scheme-specific attributes for EBR:
951 .Bl -tag -width ".Cm active"
955 The scheme-specific attributes for GPT:
956 .Bl -tag -width ".Cm bootfailed"
960 stage 1 boot loader will try to boot the system from this partition.
961 Multiple partitions can be marked with the
968 Setting this attribute automatically sets the
973 stage 1 boot loader will try to boot the system from this partition only once.
974 Multiple partitions can be marked with the
983 This attribute should not be manually managed.
986 stage 1 boot loader and the
987 .Pa /etc/rc.d/gptboot
993 Setting this attribute overwrites the Protective MBR with a new one where
994 the 0xee partition is the second, rather than the first record.
995 This resolves a BIOS compatibility issue with some Lenovo models including the
996 X220, T420, and T520, allowing them to boot from GPT partitioned disks
1000 The scheme-specific attributes for MBR:
1001 .Bl -tag -width ".Cm active"
1006 supports several partitioning schemes and each scheme uses different
1008 The bootstrap code is located in a specific disk area for each partitioning
1009 scheme, and may vary in size for different schemes.
1011 Bootstrap code can be separated into two types.
1012 The first type is embedded in the partitioning scheme's metadata, while the
1013 second type is located on a specific partition.
1014 Embedding bootstrap code should only be done with the
1019 The GEOM PART class knows how to safely embed bootstrap code into
1020 specific partitioning scheme metadata without causing any damage.
1022 The Master Boot Record (MBR) uses a 512-byte bootstrap code image, embedded
1023 into the partition table's metadata area.
1024 There are two variants of this bootstrap code:
1029 searches for a partition with the
1033 section) in the partition table.
1034 Then it runs next bootstrap stage.
1037 image contains a boot manager with some additional interactive functions
1038 for multi-booting from a user-selected partition.
1040 A BSD disklabel is usually created inside an MBR partition (slice)
1044 .Sx "PARTITION TYPES"
1046 It uses 8 KB size bootstrap code image
1048 embedded into the partition table's metadata area.
1050 Both types of bootstrap code are used to boot from the GUID Partition Table.
1051 First, a protective MBR is embedded into the first disk sector from the
1054 It searches through the GPT for a
1057 .Sx "PARTITION TYPES"
1058 section) and runs the next bootstrap stage from it.
1061 partition should be smaller than 545 KB.
1062 It can be located either before or after other
1064 partitions on the disk.
1065 There are two variants of bootstrap code to write to this partition:
1068 .Pa /boot/gptzfsboot .
1071 is used to boot from UFS partitions.
1075 partitions in the GPT and selects one to boot based on the
1080 If neither attribute is found,
1082 boots from the first
1086 .Pq the third bootstrap stage
1087 is loaded from the first partition that matches these conditions.
1090 for more information.
1092 .Pa /boot/gptzfsboot
1093 is used to boot from ZFS.
1094 It searches through the GPT for
1096 partitions, trying to detect ZFS pools.
1097 After all pools are detected,
1099 is started from the first one found set as bootable.
1101 The VTOC8 scheme does not support embedding bootstrap code.
1102 Instead, the 8 KBytes bootstrap code image
1104 should be written with the
1108 option to all sufficiently large VTOC8 partitions.
1111 option could be omitted.
1113 The APM scheme also does not support embedding bootstrap code.
1114 Instead, the 800 KBytes bootstrap code image
1116 should be written with the
1118 command to a partition of type
1120 which should also be 800 KB in size.
1121 .Sh OPERATIONAL FLAGS
1122 Actions other than the
1126 actions take an optional
1129 This option is used to specify action-specific operational flags.
1134 flag so that the action is immediately
1136 The user can specify
1138 to have the action result in a pending change that can later, with
1139 other pending changes, be committed as a single compound change with
1142 action or reverted with the
1146 The GEOM PART class supports recovering of partition tables only for GPT.
1147 The GPT primary metadata is stored at the beginning of the device.
1148 For redundancy, a secondary
1150 copy of the metadata is stored at the end of the device.
1151 As a result of having two copies, some corruption of metadata is not
1152 fatal to the working of GPT.
1153 When the kernel detects corrupt metadata, it marks this table as corrupt
1154 and reports the problem.
1158 are the only operations allowed on corrupt tables.
1160 If one GPT header appears to be corrupt but the other copy remains intact,
1161 the kernel will log the following:
1162 .Bd -literal -offset indent
1163 GEOM: provider: the primary GPT table is corrupt or invalid.
1164 GEOM: provider: using the secondary instead -- recovery strongly advised.
1168 .Bd -literal -offset indent
1169 GEOM: provider: the secondary GPT table is corrupt or invalid.
1170 GEOM: provider: using the primary only -- recovery suggested.
1179 will report about corrupt tables.
1181 If the size of the device has changed (e.g.,\& volume expansion) the
1182 secondary GPT header will no longer be located in the last sector.
1183 This is not a metadata corruption, but it is dangerous because any
1184 corruption of the primary GPT will lead to loss of the partition table.
1185 This problem is reported by the kernel with the message:
1186 .Bd -literal -offset indent
1187 GEOM: provider: the secondary GPT header is not in the last LBA.
1190 This situation can be recovered with the
1193 This command reconstructs the corrupt metadata using known valid
1194 metadata and relocates the secondary GPT to the end of the device.
1197 The GEOM PART class can detect the same partition table visible through
1198 different GEOM providers, and some of them will be marked as corrupt.
1199 Be careful when choosing a provider for recovery.
1200 If you choose incorrectly you can destroy the metadata of another GEOM class,
1201 e.g.,\& GEOM MIRROR or GEOM LABEL.
1202 .Sh SYSCTL VARIABLES
1205 variables can be used to control the behavior of the
1208 The default value is shown next to each variable.
1209 .Bl -tag -width indent
1210 .It Va kern.geom.part.auto_resize: No 1
1211 This variable controls automatic resize behavior of
1214 When this variable is enable and new size of provider is detected, the schema
1215 metadata is resized but all changes are not saved to disk, until
1217 is run to confirm changes.
1218 This behavior is also reported with diagnostic message:
1219 .Sy "GEOM_PART: (provider) was automatically resized."
1220 .Sy "Use `gpart commit (provider)` to save changes or `gpart undo (provider)`"
1221 .Sy "to revert them."
1222 .It Va kern.geom.part.check_integrity : No 1
1223 This variable controls the behaviour of metadata integrity checks.
1224 When integrity checks are enabled, the
1226 GEOM class verifies all generic partition parameters obtained from the
1228 If some inconsistency is detected, the partition table will be
1229 rejected with a diagnostic message:
1230 .Sy "GEOM_PART: Integrity check failed (provider, scheme)" .
1231 .It Va kern.geom.part.ldm.debug : No 0
1232 Debug level of the Logical Disk Manager (LDM) module.
1233 This can be set to a number between 0 and 2 inclusive.
1234 If set to 0 minimal debug information is printed,
1235 and if set to 2 the maximum amount of debug information is printed.
1236 .It Va kern.geom.part.ldm.show_mirrors : No 0
1237 This variable controls how the Logical Disk Manager (LDM) module handles
1239 By default mirrored volumes are shown as partitions with type
1242 .Sx "PARTITION TYPES"
1244 If this variable set to 1 each component of the mirrored volume will be
1245 present as independent partition.
1247 This may break a mirrored volume and lead to data damage.
1248 .It Va kern.geom.part.mbr.enforce_chs : No 0
1249 Specify how the Master Boot Record (MBR) module does alignment.
1250 If this variable is set to a non-zero value, the module will automatically
1251 recalculate the user-specified offset and size for alignment with the CHS
1253 Otherwise the values will be left unchanged.
1256 Exit status is 0 on success, and 1 if the command fails.
1258 The examples below assume that the disk's logical block size is 512
1259 bytes, regardless of its physical block size.
1261 In this example, we will format
1263 with the GPT scheme and create boot, swap and root partitions.
1264 First, we need to create the partition table:
1265 .Bd -literal -offset indent
1266 /sbin/gpart create -s GPT ada0
1269 Next, we install a protective MBR with the first-stage bootstrap code.
1270 The protective MBR lists a single, bootable partition spanning the
1271 entire disk, thus allowing non-GPT-aware BIOSes to boot from the disk
1272 and preventing tools which do not understand the GPT scheme from
1273 considering the disk to be unformatted.
1274 .Bd -literal -offset indent
1275 /sbin/gpart bootcode -b /boot/pmbr ada0
1278 We then create a dedicated
1280 partition to hold the second-stage boot loader, which will load the
1282 kernel and modules from a UFS or ZFS filesystem.
1283 This partition must be larger than the bootstrap code
1288 .Pa /boot/gptzfsboot
1291 but smaller than 545 kB since the first-stage loader will load the
1292 entire partition into memory during boot, regardless of how much data
1293 it actually contains.
1294 We create a 472-block (236 kB) boot partition at offset 40, which is
1295 the size of the partition table (34 blocks or 17 kB) rounded up to the
1296 nearest 4 kB boundary.
1297 .Bd -literal -offset indent
1298 /sbin/gpart add -b 40 -s 472 -t freebsd-boot ada0
1299 /sbin/gpart bootcode -p /boot/gptboot -i 1 ada0
1302 We now create a 4 GB swap partition at the first available offset,
1303 which is 40 + 472 = 512 blocks (256 kB).
1304 .Bd -literal -offset indent
1305 /sbin/gpart add -s 4G -t freebsd-swap ada0
1308 Aligning the swap partition and all subsequent partitions on a 256 kB
1309 boundary ensures optimal performance on a wide range of media, from
1310 plain old disks with 512-byte blocks, through modern
1312 disks with 4096-byte physical blocks, to RAID volumes with stripe
1313 sizes of up to 256 kB.
1315 Finally, we create and format an 8 GB
1317 partition for the root filesystem, leaving the rest of the slice free
1318 for additional filesystems:
1319 .Bd -literal -offset indent
1320 /sbin/gpart add -s 8G -t freebsd-ufs ada0
1321 /sbin/newfs -Uj /dev/ada0p3
1324 In this example, we will format
1326 with the MBR scheme and create a single partition which we subdivide
1331 First, we create the partition table and a single 64 GB partition,
1332 then we mark that partition active (bootable) and install the
1333 first-stage boot loader:
1334 .Bd -literal -offset indent
1335 /sbin/gpart create -s MBR ada0
1336 /sbin/gpart add -t freebsd -s 64G ada0
1337 /sbin/gpart set -a active -i 1 ada0
1338 /sbin/gpart bootcode -b /boot/boot0 ada0
1341 Next, we create a disklabel in that partition
1344 in disklabel terminology
1346 with room for up to 20 partitions:
1347 .Bd -literal -offset indent
1348 /sbin/gpart create -s BSD -n 20 ada0s1
1351 We then create an 8 GB root partition and a 4 GB swap partition:
1352 .Bd -literal -offset indent
1353 /sbin/gpart add -t freebsd-ufs -s 8G ada0s1
1354 /sbin/gpart add -t freebsd-swap -s 4G ada0s1
1357 Finally, we install the appropriate boot loader for the
1360 .Bd -literal -offset indent
1361 /sbin/gpart bootcode -b /boot/boot ada0s1
1365 Create a VTOC8 scheme on
1367 .Bd -literal -offset indent
1368 /sbin/gpart create -s VTOC8 da0
1371 Create a 512MB-sized
1373 partition to contain a UFS filesystem from which the system can boot.
1374 .Bd -literal -offset indent
1375 /sbin/gpart add -s 512M -t freebsd-ufs da0
1380 partition to contain a UFS filesystem and aligned on 4KB boundaries:
1381 .Bd -literal -offset indent
1382 /sbin/gpart add -s 15G -t freebsd-ufs -a 4k da0
1385 After creating all required partitions, embed bootstrap code into them:
1386 .Bd -literal -offset indent
1387 /sbin/gpart bootcode -p /boot/boot1 da0
1389 .Ss Deleting Partitions and Destroying the Partitioning Scheme
1392 error is shown when trying to destroy a partition table, remember that
1393 all of the partitions must be deleted first with the
1398 has three partitions:
1399 .Bd -literal -offset indent
1400 /sbin/gpart delete -i 3 da0
1401 /sbin/gpart delete -i 2 da0
1402 /sbin/gpart delete -i 1 da0
1403 /sbin/gpart destroy da0
1406 Rather than deleting each partition and then destroying the partitioning
1409 option can be given with
1411 to delete all of the partitions before destroying the partitioning scheme.
1412 This is equivalent to the previous example:
1413 .Bd -literal -offset indent
1414 /sbin/gpart destroy -F da0
1416 .Ss Backup and Restore
1418 Create a backup of the partition table from
1420 .Bd -literal -offset indent
1421 /sbin/gpart backup da0 > da0.backup
1424 Restore the partition table from the backup to
1426 .Bd -literal -offset indent
1427 /sbin/gpart restore -l da0 < /mnt/da0.backup
1430 Clone the partition table from
1436 .Bd -literal -offset indent
1437 /sbin/gpart backup ada0 | /sbin/gpart restore -F ada1 ada2
1450 .An Marcel Moolenaar Aq Mt marcel@FreeBSD.org