1.\" Copyright (c) 1987, 1988, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Symmetric Computer Systems. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)disklabel.8 8.2 (Berkeley) 4/19/94 32.\" $FreeBSD: src/sbin/disklabel/disklabel.8,v 1.15.2.22 2003/04/17 17:56:34 trhodes Exp $ 33.\" 34.Dd July 21, 2018 35.Dt DISKLABEL64 8 36.Os 37.Sh NAME 38.Nm disklabel64 39.Nd read and write 64 bit disk pack label 40.Sh SYNOPSIS 41.Nm 42.Op Fl r 43.Ar disk 44.Nm 45.Fl w 46.Op Fl r 47.Op Fl n 48.Ar disk 49.Op Ar disktype Ns / Ns Cm auto Op Ar packid 50.Nm 51.Fl e 52.Op Fl r 53.Op Fl n 54.Ar disk 55.Nm 56.Fl R 57.Op Fl r 58.Op Fl n 59.Ar disk Ar protofile 60.Nm 61.Op Fl NW 62.Ar disk 63.Pp 64.Nm 65.Fl B 66.Oo 67.Fl b Ar boot1 68.Fl s Ar boot2 69.Oc 70.Ar disk 71.Oo Ar disktype Ns / Ns Cm auto Oc 72.Nm 73.Fl w 74.Fl B 75.Op Fl n 76.Oo 77.Fl b Ar boot1 78.Fl s Ar boot2 79.Oc 80.Ar disk 81.Op Ar disktype Ns / Ns Cm auto Op Ar packid 82.Nm 83.Fl R 84.Fl B 85.Op Fl n 86.Oo 87.Fl b Ar boot1 88.Fl s Ar boot2 89.Oc 90.Ar disk Ar protofile 91.Oo Ar disktype Ns / Ns Cm auto Oc 92.Sh DESCRIPTION 93The 94.Nm 95utility 96installs, examines or modifies a 64 bit label on a disk drive or pack. 97When writing 98the label, it can be used to change the drive identification, the disk 99partitions on the drive, or to replace a damaged label. 100There are several forms 101of the command that read (display), install or edit the label on a disk. 102In 103addition, 104.Nm 105can install bootstrap code. 106.Ss Raw or in-core label 107The disk label resides close to or at the beginning of each disk slice. 108For faster access, the kernel maintains a copy in core at all times. 109By 110default, most forms of the 111.Nm 112command access the in-core copy of the label. 113To access the raw (on-disk) 114copy, use the 115.Fl r 116option. 117This option allows a label to be installed on a disk without kernel 118support for a label, such as when labels are first installed on a system; it 119must be used when first installing a label on a disk. 120The specific effect of 121.Fl r 122is described under each command. 123.Ss Disk device name 124All 125.Nm 126forms require a disk device name, which should always be the raw 127device name representing the disk or slice. 128.Dx 129uses the following scheme for slice numbering: 130If the disk doesn't use GPT (typically laid out by 131.Xr gpt 8 ) , 132but e.g.\& MBR (typically laid out by 133.Xr fdisk 8 ) , 134then slice 0, e.g.\& 135.Pa da0s0 , 136represents the entire disk regardless of any DOS partitioning. 137Slice 0 is called the compatibility slice, 138and slice 1 and onward, e.g.\& 139.Pa da0s1 , 140represents a 141.Bx 142slice. 143If the disk does use GPT, then all slices are 144.Bx 145slices, slice 0 isn't special, it is just the first slice on the disk. 146You do not have to include the 147.Pa /dev/ 148path prefix when specifying the device. 149The 150.Nm 151utility will automatically prepend it. 152.Ss Reading the disk label 153To examine the label on a disk drive, use 154.Nm 155without options: 156.Pp 157.Nm 158.Op Fl r 159.Ar disk 160.Pp 161.Ar disk 162represents the raw disk in question, and may be in the form 163.Pa da0s1 164or 165.Pa /dev/da0s1 . 166It will display all of the parameters associated with the drive and its 167partition layout. 168Unless the 169.Fl r 170flag is given, 171the kernel's in-core copy of the label is displayed; 172if the disk has no label, or the partition types on the disk are incorrect, 173the kernel may have constructed or modified the label. 174If the 175.Fl r 176flag is given, 177.Nm 178reads the label from the raw disk and displays it. 179Both versions are usually 180identical except in the case where a label has not yet been initialized or 181is corrupt. 182.Ss Writing a standard label 183To write a standard label, use the form 184.Pp 185.Nm 186.Fl w 187.Op Fl r 188.Op Fl n 189.Ar disk 190.Op Ar disktype Ns / Ns Cm auto Op Ar packid 191.Pp 192The required argument to 193.Nm 194is the drive to be labeled. 195The first optional argument is the drive type as described in the 196.Xr disktab 5 197file, from which the drive parameters and partitions are taken. 198If not specified, then the 199.Cm auto 200type is assumed to make a virgin label for the disk as described below. 201If 202different disks of the same physical type are to have different partitions, it 203will be necessary to have separate disktab entries describing each, or to edit 204the label after installation as described below. 205The optional argument is a 206pack identification string, up to 63 characters long. 207The pack id must be 208quoted if it contains blanks. 209.Pp 210If the 211.Fl n 212flag is given, no data will be written to the device, and instead the 213disklabel that would have been written will be printed to stdout. 214.Pp 215If the 216.Fl r 217flag is given, the disk sectors containing the label and bootstrap 218will be written directly. 219A side-effect of this is that any existing bootstrap code will be overwritten 220and the disk rendered unbootable. 221See the boot options below for a method of 222writing the label and the bootstrap at the same time. 223If 224.Fl r 225is not specified, 226the existing label will be updated via the in-core copy and any bootstrap 227code will be unaffected. 228If the disk does not already have a label, the 229.Fl r 230flag must be used. 231In either case, the kernel's in-core label is replaced. 232.Pp 233For a virgin disk that is not known to 234.Xr disktab 5 , 235.Ar disktype 236can be specified as 237.Cm auto . 238In this case, the driver is requested to produce a virgin label for the 239disk. 240This might or might not be successful, depending on whether the 241driver for the disk is able to get the required data without reading 242anything from the disk at all. 243It will likely succeed for all SCSI 244disks, most IDE disks, and vnode devices. 245Writing a label to the 246disk is the only supported operation. 247.Pp 248For most harddisks, a label based on percentages for most partitions (and 249one partition with a size of 250.Ql * ) 251will produce a reasonable configuration. 252.Pp 253PC-based systems have special requirements in order for the BIOS to properly 254recognize a 255.Dx 256disklabel. 257Older systems may require what is known as a 258.Dq dangerously dedicated 259disklabel, which creates a fake DOS partition to work around problems older 260BIOSes have with modern disk geometries. 261On newer systems you generally want 262to create a normal DOS partition using 263.Ar fdisk 264and then create a 265.Dx 266disklabel within that slice. 267This is described 268later on in this page. 269.Pp 270Installing a new disklabel does not in of itself allow your system to boot 271a kernel using that label. 272You must also install boot blocks, which is 273described later on in this manual page. 274.Ss Editing an existing disk label 275To edit an existing disk label, use the form 276.Pp 277.Nm 278.Fl e 279.Op Fl r 280.Op Fl n 281.Ar disk 282.Pp 283This command reads the label from the in-core kernel copy, or directly from the 284disk if the 285.Fl r 286flag is also specified. 287The label is written to a file in ASCII and then 288supplied to an editor for changes. 289If no editor is specified in an 290.Ev EDITOR 291environment variable, 292.Xr vi 1 293is used. 294When the editor terminates, the label file is used to rewrite the disk label. 295Existing bootstrap code is unchanged regardless of whether 296.Fl r 297was specified. 298If 299.Fl n 300is specified, no data will be written to the device, and instead the 301disklabel that would have been written will be printed to stdout. 302This is 303useful to see how a partitioning scheme will work out for a specific disk. 304.Ss Restoring a disk label from a file 305To restore a disk label from a file, use the form 306.Pp 307.Nm 308.Fl R 309.Op Fl r 310.Op Fl n 311.Ar disk Ar protofile 312.Pp 313.Nm 314is capable of restoring a disk label that was previously saved in a file 315in ASCII format. 316The prototype file used to create the label should be in the same format 317as that produced when reading or editing a label. 318Comments are delimited by 319.Ql # 320and newline. 321As when writing a new label, any existing bootstrap code will be 322clobbered if 323.Fl r 324is specified and will be unaffected otherwise. 325See the boot options below for a 326method of restoring the label and writing the bootstrap at the same time. 327If 328.Fl n 329is used, no data will be written to the device, and instead the 330disklabel that would have been written will be printed to stdout. 331This is 332useful to see how a partitioning scheme will work out for a specific disk. 333.Ss Enabling and disabling writing to the disk label area 334By default, it is not possible to write to the disk label area at the beginning 335of a disk. 336The disk driver arranges for 337.Xr write 2 338and similar system calls 339to return 340.Er EROFS 341on any attempt to do so. 342If you need 343to write to this area (for example, to obliterate the label), use the form 344.Pp 345.Nm 346.Fl W 347.Ar disk 348.Pp 349To disallow writing to the label area after previously allowing it, 350use the command 351.Pp 352.Nm 353.Fl N 354.Ar disk 355.Ss Installing bootstraps 356The final three forms of 357.Nm 358are used to install bootstrap code, which allows boot from a 359.Xr HAMMER 5 , 360.Xr HAMMER2 5 , 361or 362.Xr UFS 5 363file system. 364If you are creating a 365.Dq dangerously-dedicated 366slice for compatibility with older PC systems, 367you generally want to specify the compatibility slice, such as 368.Pa da0s0 . 369If you are creating a label within an existing DOS slice, 370you should specify 371the slice name such as 372.Pa da0s1 . 373Making a slice bootable can be tricky. 374If you are using a normal DOS 375slice you typically install (or leave) a standard MBR on the base disk and 376then install the 377.Dx 378bootblocks in the slice. 379.Pp 380.Nm 381.Fl B 382.Oo 383.Fl b Ar boot1 384.Fl s Ar boot2 385.Oc 386.Ar disk 387.Oo Ar disktype Ns / Ns Cm auto Oc 388.Pp 389This form installs the bootstrap only. 390It does not change the disk label. 391You should never use this command on the compatibility slice unless you 392intend to create a 393.Dq dangerously-dedicated 394disk, such as 395.Ar da0s0 . 396This command is typically run on a 397.Bx 398slice such as 399.Ar da0s1 . 400.Pp 401.Nm 402.Fl w 403.Fl B 404.Op Fl n 405.Oo 406.Fl b Ar boot1 407.Fl s Ar boot2 408.Oc 409.Ar disk 410.Op Ar disktype Ns / Ns Cm auto Op Ar packid 411.Pp 412This form corresponds to the 413.Dq write label 414command described above. 415In addition to writing a new volume label, it also installs the bootstrap. 416If run on the compatibility slice this command will create a 417.Dq dangerously-dedicated 418label. 419This command is normally run on a 420.Bx 421slice rather than the compatibility slice. 422If 423.Fl n 424is used, no data will be written to the device, and instead the 425disklabel that would have been written will be printed to stdout. 426.Pp 427.Nm 428.Fl R 429.Fl B 430.Op Fl n 431.Oo 432.Fl b Ar boot1 433.Fl s Ar boot2 434.Oc 435.Ar disk Ar protofile 436.Oo Ar disktype Ns / Ns Cm auto Oc 437.Pp 438This form corresponds to the 439.Dq restore label 440command described above. 441In addition to restoring the volume label, it also installs the bootstrap. 442If run on the compatibility slice this command will create a 443.Dq dangerously-dedicated 444label. 445This command is normally run on a 446.Bx 447slice rather than the compatibility 448slice. 449.Pp 450The bootstrap commands always access the disk directly, 451so it is not necessary to specify the 452.Fl r 453flag. 454If 455.Fl n 456is used, no data will be written to the device, and instead the 457disklabel that would have been written will be printed to stdout. 458.Pp 459The bootstrap code is comprised of two boot programs. 460Specify the name of the 461boot programs to be installed in one of these ways: 462.Bl -enum 463.It 464Specify the names explicitly with the 465.Fl b 466and 467.Fl s 468flags. 469.Fl b 470indicates the primary boot program and 471.Fl s 472the secondary boot program. 473The boot programs are normally located in 474.Pa /boot . 475.It 476If the 477.Fl b 478and 479.Fl s 480flags are not specified, but 481.Ar disktype 482was specified, the names of the programs are taken from the 483.Dq b0 484and 485.Dq b1 486parameters of the 487.Xr disktab 5 488entry for the disk if the disktab entry exists and includes those parameters. 489.It 490Otherwise, the default boot image names are used: 491.Pa /boot/boot1_64 492and 493.Pa /boot/boot2_64 494for the standard stage1 and stage2 boot images. 495.El 496.Ss Initializing/Formatting a bootable disk from scratch 497To initialize a disk from scratch the following sequence is recommended. 498Please note that this will wipe everything that was previously on the disk, 499including any 500.No non- Ns Dx 501slices. 502.Bl -enum 503.It 504Use 505.Xr gpt 8 506or 507.Xr fdisk 8 508to initialize the hard disk, and create a GPT or MBR slice table, 509referred to as the 510.Dq "partition table" 511in 512.Tn DOS . 513.It 514Use 515.Nm 516or 517.Xr disklabel32 8 518to define partitions on 519.Dx 520slices created in the previous step. 521.It 522Finally use 523.Xr newfs_hammer 8 , 524.Xr newfs_hammer2 8 , 525or 526.Xr newfs 8 527to create file systems on new partitions. 528.El 529.Pp 530A typical partitioning scheme would be to have an 531.Ql a 532partition of approximately 1 GB for 533.Pa /boot 534to hold the current, old (and backup) kernels and modules, a 535.Ql b 536partition for swap (suggested to be at least the same size as the 537physical memory), 538and finally a 539.Ql d 540partition for the root file system (usually all remaining space). 541Your mileage may vary. 542.Pp 543.Dl "gpt create da0" 544.Dl "gpt add da0" 545.Dl "disklabel64 -B -r -w da0s0" 546.Dl "disklabel64 -e da0s0" 547.Sh ALIGNMENT 548When a virgin disklabel64 is laid down a 549.Dx 2.5 550or later kernel will align the partition start offset relative to the 551physical drive instead of relative to the slice start. 552This overcomes the issue of fdisk creating a badly aligned slice by default. 553The kernel will use a 1MiB (1024 * 1024 byte) alignment. 554The purpose of this alignment is to match swap and cluster operations 555against the physical block size of the underlying device. 556.Pp 557Even though nearly all devices still report a logical sector size of 512, 558newer hard drives are starting to use larger physical sector sizes 559and, in particular, solid state drives (SSDs) use a physical block size 560of 64K (SLC) or 128K (MLC). We choose a 1 megabyte alignment to cover our 561bases down the road. 64-bit disklabels are not designed to be put on 562ultra-tiny storage devices. 563.Pp 564It is worth noting that aligning cluster operations is particularly 565important for SSDs and doubly so when 566.Xr swapcache 8 567is used with a SSD. 568Swapcache is able to use large bulk writes which greatly reduces the degree 569of write magnification on SSD media and it is possible to get upwards of 5705x more endurance out of the device than the vendor spec sheet indicates. 571.Sh FILES 572.Bl -tag -width ".Pa /boot/boot2_64" -compact 573.It Pa /boot/boot1_64 574Default stage1 boot image. 575.It Pa /boot/boot2_64 576Default stage2 boot image. 577.It Pa /etc/disktab 578Disk description file. 579.El 580.Sh SAVED FILE FORMAT 581The 582.Nm 583utility uses an 584.Tn ASCII 585version of the label when examining, editing, or restoring a disk label. 586An example shows as below: 587.Bd -literal -offset 4n 588# /dev/ad0s1: 589# 590# Calculated informational fields for the slice: 591# 592# boot space: 1012224 bytes 593# data space: 156286976 blocks # 152624.00 MB (160037863424 bytes) 594# 595# NOTE: The partition data base and stop are physically 596# aligned instead of slice-relative aligned. 597# 598# All byte equivalent offsets must be aligned. 599# 600diskid: 5dc53a64-c5e5-11e7-8aec-011d0988acd3 601label: 602boot2 data base: 0x000000001000 603partitions data base: 0x0000000f8200 604partitions data stop: 0x0025430f8200 605backup label: 0x002543157200 606total size: 0x002543158200 # 152625.34 MB 607alignment: 4096 608display block size: 1024 # for partition display and edit only 609 61016 partitions: 611# size offset fstype fsuuid 612 a: 1048576 0 4.2BSD # 1024.000MB 613 b: 16777216 1048576 swap # 16384.000MB 614 d: 138461184 17825792 HAMMER # 135216.000MB 615 a-stor_uuid: 7f1ff0ee-c5ec-11e7-8aec-011d0988acd3 616 b-stor_uuid: 7f1ff0fc-c5ec-11e7-8aec-011d0988acd3 617 d-stor_uuid: 7f1ff108-c5ec-11e7-8aec-011d0988acd3 618.Ed 619.Pp 620Lines starting with a 621.Ql # 622mark are comments. 623The specifications which can be changed are: 624.Bl -inset 625.It Ar label 626is an optional label, set by the 627.Ar packid 628option when writing a label. 629.It Ar "the partition table" 630is the 631.Ux 632partition table, not the 633.Tn DOS 634partition table described in 635.Xr fdisk 8 . 636.El 637.Pp 638The partition table can have up to 16 entries. 639It contains the following information: 640.Bl -tag -width indent 641.It Ar # 642The partition identifier is a single letter in the range 643.Ql a 644to 645.Ql p . 646.It Ar size 647The size of the partition in sectors, 648.Cm K 649(kilobytes - 1024), 650.Cm M 651(megabytes - 1024*1024), 652.Cm G 653(gigabytes - 1024*1024*1024), 654.Cm T 655(terabytes - 1024*1024*1024*1024), 656.Cm % 657(percentage of free space 658.Em after 659removing any fixed-size partitions), 660.Cm * 661(all remaining free space 662.Em after 663fixed-size and percentage partitions). 664Lowercase versions of 665.Cm K , M , G , 666and 667.Cm T 668are allowed. 669Size and type should be specified without any spaces between them. 670.Pp 671Example: 2097152, 1G, 1024M and 1048576K are all the same size 672(assuming 512-byte sectors). 673.It Ar offset 674The offset of the start of the partition from the beginning of the 675drive in sectors, or 676.Cm * 677to have 678.Nm 679calculate the correct offset to use (the end of the previous partition plus 680one. 681.It Ar fstype 682The name of the filesystem type for the partition (case insensitive). 683For 684.Xr UFS 5 685file systems, use type 686.Cm 4.2BSD . 687For 688.Xr HAMMER 5 689file systems, use type 690.Cm HAMMER . 691For 692.Xr hammer2 8 693file systems, use type 694.Cm HAMMER2 . 695For 696.Xr ccd 4 697partitions, use type 698.Cm ccd . 699For Vinum drives, use type 700.Cm vinum . 701Other common types are 702.Cm swap 703and 704.Cm unused . 705The 706.Nm 707utility 708also knows about a number of other partition types, 709none of which are in current use. 710(See 711.Dv fstypenames 712in 713.In sys/dtype.h 714for more details). 715.El 716.Pp 717The remainder of the line is a comment and shows the size of 718the partition in MB. 719.Sh EXAMPLES 720.Dl "disklabel64 da0s1" 721.Pp 722Display the in-core label for the first slice of the 723.Pa da0 724disk, as obtained via 725.Pa /dev/da0s1 . 726(If the disk is 727.Dq dangerously-dedicated , 728the compatibility slice name should be specified, such as 729.Pa da0s0 . ) 730.Pp 731.Dl "disklabel64 da0s1 > savedlabel" 732.Pp 733Save the in-core label for 734.Pa da0s1 735into the file 736.Pa savedlabel . 737This file can be used with the 738.Fl R 739option to restore the label at a later date. 740.Pp 741.Dl "disklabel64 -e -r da0s1" 742.Pp 743Read the on-disk label for 744.Pa da0s1 , 745edit it, and reinstall in-core as well as on-disk. 746Existing bootstrap code is unaffected. 747.Pp 748.Dl "disklabel64 -e -r -n da0s1" 749.Pp 750Read the on-disk label for 751.Pa da0s1 , 752edit it, and display what the new label would be. 753It does 754.Em not 755install the new label either in-core or on-disk. 756.Pp 757.Dl "disklabel64 -r -w da0s1" 758.Pp 759Try to auto-detect the required information from 760.Pa da0s1 , 761and write a new label to the disk. 762Use another 763.Nm Fl e 764command to edit the partitioning information. 765.Pp 766.Dl "disklabel64 -R da0s1 savedlabel" 767.Pp 768Restore the on-disk and in-core label for 769.Pa da0s1 770from information in 771.Pa savedlabel . 772Existing bootstrap code is unaffected. 773.Pp 774.Dl "disklabel64 -R -n da0s1 label_layout" 775.Pp 776Display what the label would be for 777.Pa da0s1 778using the partition layout in 779.Pa label_layout . 780This is useful for determining how much space would be allotted for various 781partitions with a labelling scheme using 782.Cm % Ns -based 783or 784.Cm * 785partition sizes. 786.Pp 787.Dl "disklabel64 -B da0s1" 788.Pp 789Install a new bootstrap on 790.Pa da0s1 . 791The boot code comes from 792.Pa /boot/boot1_64 793and possibly 794.Pa /boot/boot2_64 . 795On-disk and in-core labels are unchanged. 796.Pp 797.Dl "disklabel64 -w -B /dev/da0s1 -b newboot1 -s newboot2" 798.Pp 799Install a new label and bootstrap, with bootstrap code comes from the files 800.Pa newboot1 801and 802.Pa newboot2 . 803.Pp 804.Dl "dd if=/dev/zero of=/dev/da0 bs=512 count=32" 805.Dl "fdisk -BI da0" 806.Dl "dd if=/dev/zero of=/dev/da0s1 bs=512 count=32" 807.Dl "disklabel64 -w -B da0s1" 808.Dl "disklabel64 -e da0s1" 809.Pp 810Completely wipe any prior information on the disk, creating a new bootable 811disk with a DOS partition table containing one 812.Dq whole-disk 813slice. 814Then 815initialize the slice, then edit it to your needs. 816The 817.Pa dd 818commands are optional, but may be necessary for some BIOSes to properly 819recognize the disk. 820.Pp 821.Dl "disklabel64 -W da0s1" 822.Dl "dd if=/dev/zero of=/dev/da0s1 bs=512 count=32" 823.Dl "disklabel32 -r -w da0s1" 824.Dl "disklabel32 -N da0s1" 825.Pp 826Completely wipe any prior information on the slice, 827and install the old 32-bit label. 828The wiping is needed because both 829.Nm disklabel32 830and 831.Nm , 832as a safety measure, 833won't do any operations if label with other format is already installed. 834.Pp 835This is an example disklabel that uses some of the new partition size types 836such as 837.Cm % , M , G , T , 838and 839.Cm * , 840which could be used as a source file for: 841.Pp 842.Dl "disklabel64 -R ad0s1 new_label_file" 843.Bd -literal -offset 4n 844# /dev/ad0s1: 845# 846# Calculated informational fields for the slice: 847# 848# boot space: 1012224 bytes 849# data space: 156286976 blocks # 152624.00 MB (160037863424 bytes) 850# 851# NOTE: The partition data base and stop are physically 852# aligned instead of slice-relative aligned. 853# 854# All byte equivalent offsets must be aligned. 855# 856diskid: 5dc53a64-c5e5-11e7-8aec-011d0988acd3 857label: 858boot2 data base: 0x000000001000 859partitions data base: 0x0000000f8200 860partitions data stop: 0x0025430f8200 861backup label: 0x002543157200 862total size: 0x002543158200 # 152625.34 MB 863alignment: 4096 864display block size: 1024 # for partition display and edit only 865 86616 partitions: 867# size offset fstype fsuuid 868 a: 1024M 0 4.2BSD 869 b: 4G * swap 870 d: 2G * 4.2BSD 871 e: 2048M * 4.2BSD 872 f: 4G * 4.2BSD 873 g: 4G * 4.2BSD 874 h: 50G * HAMMER 875 i: * * HAMMER2 876 j: 5g * ccd 877 k: 5120m * vinum 878.Ed 879.Sh DIAGNOSTICS 880The kernel device drivers will not allow the size of a disk partition 881to be decreased or the offset of a partition to be changed while it is open. 882Some device drivers create a label containing only a single large partition 883if a disk is unlabeled; thus, the label must be written to the 884.Ql a 885partition of the disk while it is open. 886This sometimes requires the desired 887label to be set in two steps, the first one creating at least one other 888partition, and the second setting the label on the new partition while 889shrinking the 890.Ql a 891partition. 892.Sh SEE ALSO 893.Xr dd 1 , 894.Xr uuid 3 , 895.Xr ccd 4 , 896.Xr disklabel64 5 , 897.Xr disktab 5 , 898.Xr boot0cfg 8 , 899.Xr diskinfo 8 , 900.Xr disklabel32 8 , 901.Xr fdisk 8 , 902.Xr gpt 8 , 903.Xr hammer2 8 , 904.Xr newfs 8 , 905.Xr newfs_hammer 8 , 906.Xr newfs_hammer2 8 , 907.Xr vinum 8 908.Sh BUGS 909The 910.Nm 911utility 912does not perform all possible error checking. 913Warning 914.Em is 915given if partitions 916overlap; if an absolute offset does not match the expected offset; if a 917partition runs past the end of the device; and a number of other errors; but 918no warning is given if space remains unused. 919.Pp 920The 921.Xr disktab 5 922support is not implemented. 923