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. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgment: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)disklabel.8 8.2 (Berkeley) 4/19/94 36.\" $FreeBSD: src/sbin/disklabel/disklabel.8,v 1.15.2.22 2003/04/17 17:56:34 trhodes Exp $ 37.\" $DragonFly: src/sbin/disklabel64/disklabel64.8,v 1.13 2008/09/16 20:45:36 thomas Exp $ 38.\" 39.Dd September 28, 2009 40.Dt DISKLABEL64 8 41.Os 42.Sh NAME 43.Nm disklabel64 44.Nd read and write 64 bit disk pack label 45.Sh SYNOPSIS 46.Nm 47.Op Fl r 48.Ar disk 49.Nm 50.Fl w 51.Op Fl r 52.Op Fl n 53.Ar disk Ar disktype Ns / Ns Cm auto 54.Oo Ar packid Oc 55.Nm 56.Fl e 57.Op Fl r 58.Op Fl n 59.Ar disk 60.Nm 61.Fl R 62.Op Fl r 63.Op Fl n 64.Ar disk Ar protofile 65.Nm 66.Op Fl NW 67.Ar disk 68.Pp 69.Nm 70.Fl B 71.Oo 72.Fl b Ar boot1 73.Fl s Ar boot2 74.Oc 75.Ar disk 76.Oo Ar disktype Ns / Ns Cm auto Oc 77.Nm 78.Fl w 79.Fl B 80.Op Fl n 81.Oo 82.Fl b Ar boot1 83.Fl s Ar boot2 84.Oc 85.Ar disk Ar disktype Ns / Ns Cm auto 86.Oo Ar packid Oc 87.Nm 88.Fl R 89.Fl B 90.Op Fl n 91.Oo 92.Fl b Ar boot1 93.Fl s Ar boot2 94.Oc 95.Ar disk Ar protofile 96.Oo Ar disktype Ns / Ns Cm auto Oc 97.Sh DESCRIPTION 98The 99.Nm 100utility 101installs, examines or modifies a 64 bit label on a disk drive or pack. 102When writing 103the label, it can be used to change the drive identification, the disk 104partitions on the drive, or to replace a damaged label. 105There are several forms 106of the command that read (display), install or edit the label on a disk. 107In 108addition, 109.Nm 110can install bootstrap code. 111.Ss Raw or in-core label 112The disk label resides close to or at the beginning of each disk slice. 113For faster access, the kernel maintains a copy in core at all times. 114By 115default, most forms of the 116.Nm 117command access the in-core copy of the label. 118To access the raw (on-disk) 119copy, use the 120.Fl r 121option. 122This option allows a label to be installed on a disk without kernel 123support for a label, such as when labels are first installed on a system; it 124must be used when first installing a label on a disk. 125The specific effect of 126.Fl r 127is described under each command. 128.Ss Disk device name 129All 130.Nm 131forms require a disk device name, which should always be the raw 132device name representing the disk or slice. 133.Dx 134uses the following scheme for slice numbering: 135If the disk doesn't use GPT (typically laid out by 136.Xr gpt 8 ) , 137but e.g.\& MBR (typically laid out by 138.Xr fdisk 8 ) , 139then slice 0, e.g.\& 140.Pa da0s0 , 141represents the entire disk regardless of any DOS partitioning. 142Slice 0 is called the compatibility slice, 143and slice 1 and onward, e.g.\& 144.Pa da0s1 , 145represents a 146.Bx 147slice. 148If the disk does use GPT, then all slices are 149.Bx 150slices, slice 0 isn't special, it is just the first slice on the disk. 151You do not have to include the 152.Pa /dev/ 153path prefix when specifying the device. 154The 155.Nm 156utility will automatically prepend it. 157.Ss Reading the disk label 158To examine the label on a disk drive, use 159.Nm 160without options: 161.Pp 162.Nm 163.Op Fl r 164.Ar disk 165.Pp 166.Ar disk 167represents the raw disk in question, and may be in the form 168.Pa da0s1 169or 170.Pa /dev/da0s1 . 171It will display all of the parameters associated with the drive and its 172partition layout. 173Unless the 174.Fl r 175flag is given, 176the kernel's in-core copy of the label is displayed; 177if the disk has no label, or the partition types on the disk are incorrect, 178the kernel may have constructed or modified the label. 179If the 180.Fl r 181flag is given, 182.Nm 183reads the label from the raw disk and displays it. 184Both versions are usually 185identical except in the case where a label has not yet been initialized or 186is corrupt. 187.Ss Writing a standard label 188To write a standard label, use the form 189.Pp 190.Nm 191.Fl w 192.Op Fl r 193.Op Fl n 194.Ar disk Ar disktype Ns / Ns Cm auto 195.Oo Ar packid Oc 196.Pp 197The required arguments to 198.Nm 199are the drive to be labeled and the drive type as described in the 200.Xr disktab 5 201file. 202The drive parameters and partitions are taken from that file. 203If 204different disks of the same physical type are to have different partitions, it 205will be necessary to have separate disktab entries describing each, or to edit 206the label after installation as described below. 207The optional argument is a 208pack identification string, up to 16 characters long. 209The pack id must be 210quoted if it contains blanks. 211.Pp 212If the 213.Fl n 214flag is given, no data will be written to the device, and instead the 215disklabel that would have been written will be printed to stdout. 216.Pp 217If the 218.Fl r 219flag is given, the disk sectors containing the label and bootstrap 220will be written directly. 221A side-effect of this is that any existing bootstrap code will be overwritten 222and the disk rendered unbootable. 223See the boot options below for a method of 224writing the label and the bootstrap at the same time. 225If 226.Fl r 227is not specified, 228the existing label will be updated via the in-core copy and any bootstrap 229code will be unaffected. 230If the disk does not already have a label, the 231.Fl r 232flag must be used. 233In either case, the kernel's in-core label is replaced. 234.Pp 235For a virgin disk that is not known to 236.Xr disktab 5 , 237.Ar disktype 238can be specified as 239.Cm auto . 240In this case, the driver is requested to produce a virgin label for the 241disk. 242This might or might not be successful, depending on whether the 243driver for the disk is able to get the required data without reading 244anything from the disk at all. 245It will likely succeed for all SCSI 246disks, most IDE disks, and vnode devices. 247Writing a label to the 248disk is the only supported operation, and the 249.Ar disk 250itself must be provided as the canonical name, i.e.\& not as a full 251path name. 252.Pp 253For most harddisks, a label based on percentages for most partitions (and 254one partition with a size of 255.Ql * ) 256will produce a reasonable configuration. 257.Pp 258PC-based systems have special requirements in order for the BIOS to properly 259recognize a 260.Dx 261disklabel. 262Older systems may require what is known as a 263.Dq dangerously dedicated 264disklabel, which creates a fake DOS partition to work around problems older 265BIOSes have with modern disk geometries. 266On newer systems you generally want 267to create a normal DOS partition using 268.Ar fdisk 269and then create a 270.Dx 271disklabel within that slice. 272This is described 273later on in this page. 274.Pp 275Installing a new disklabel does not in of itself allow your system to boot 276a kernel using that label. 277You must also install boot blocks, which is 278described later on in this manual page. 279.Ss Editing an existing disk label 280To edit an existing disk label, use the form 281.Pp 282.Nm 283.Fl e 284.Op Fl r 285.Op Fl n 286.Ar disk 287.Pp 288This command reads the label from the in-core kernel copy, or directly from the 289disk if the 290.Fl r 291flag is also specified. 292The label is written to a file in ASCII and then 293supplied to an editor for changes. 294If no editor is specified in an 295.Ev EDITOR 296environment variable, 297.Xr vi 1 298is used. 299When the editor terminates, the label file is used to rewrite the disk label. 300Existing bootstrap code is unchanged regardless of whether 301.Fl r 302was specified. 303If 304.Fl n 305is specified, no data will be written to the device, and instead the 306disklabel that would have been written will be printed to stdout. 307This is 308useful to see how a partitioning scheme will work out for a specific disk. 309.Ss Restoring a disk label from a file 310To restore a disk label from a file, use the form 311.Pp 312.Nm 313.Fl R 314.Op Fl r 315.Op Fl n 316.Ar disk Ar protofile 317.Pp 318.Nm 319is capable of restoring a disk label that was previously saved in a file 320in ASCII format. 321The prototype file used to create the label should be in the same format 322as that produced when reading or editing a label. 323Comments are delimited by 324.Ql # 325and newline. 326As when writing a new label, any existing bootstrap code will be 327clobbered if 328.Fl r 329is specified and will be unaffected otherwise. 330See the boot options below for a 331method of restoring the label and writing the bootstrap at the same time. 332If 333.Fl n 334is used, no data will be written to the device, and instead the 335disklabel that would have been written will be printed to stdout. 336This is 337useful to see how a partitioning scheme will work out for a specific disk. 338.Ss Enabling and disabling writing to the disk label area 339By default, it is not possible to write to the disk label area at the beginning 340of a disk. 341The disk driver arranges for 342.Xr write 2 343and similar system calls 344to return 345.Er EROFS 346on any attempt to do so. 347If you need 348to write to this area (for example, to obliterate the label), use the form 349.Pp 350.Nm 351.Fl W 352.Ar disk 353.Pp 354To disallow writing to the label area after previously allowing it, 355use the command 356.Pp 357.Nm 358.Fl N 359.Ar disk 360.Ss Installing bootstraps 361The final three forms of 362.Nm 363are used to install bootstrap code, which allows boot from a 364.Xr HAMMER 5 365or 366.Xr UFS 5 367file system. 368If you are creating a 369.Dq dangerously-dedicated 370slice for compatibility with older PC systems, 371you generally want to specify the compatibility slice, such as 372.Pa da0s0 . 373If you are creating a label within an existing DOS slice, 374you should specify 375the slice name such as 376.Pa da0s1 . 377Making a slice bootable can be tricky. 378If you are using a normal DOS 379slice you typically install (or leave) a standard MBR on the base disk and 380then install the 381.Dx 382bootblocks in the slice. 383.Pp 384.Nm 385.Fl B 386.Oo 387.Fl b Ar boot1 388.Fl s Ar boot2 389.Oc 390.Ar disk 391.Oo Ar disktype Ns / Ns Cm auto Oc 392.Pp 393This form installs the bootstrap only. 394It does not change the disk label. 395You should never use this command on the compatibility slice unless you 396intend to create a 397.Dq dangerously-dedicated 398disk, such as 399.Ar da0s0 . 400This command is typically run on a 401.Bx 402slice such as 403.Ar da0s1 . 404.Pp 405.Nm 406.Fl w 407.Fl B 408.Op Fl n 409.Oo 410.Fl b Ar boot1 411.Fl s Ar boot2 412.Oc 413.Ar disk Ar disktype Ns / Ns Cm auto 414.Oo Ar packid Oc 415.Pp 416This form corresponds to the 417.Dq write label 418command described above. 419In addition to writing a new volume label, it also installs the bootstrap. 420If run on the compatibility slice this command will create a 421.Dq dangerously-dedicated 422label. 423This command is normally run on a 424.Bx 425slice rather than the compatibility slice. 426If 427.Fl n 428is used, no data will be written to the device, and instead the 429disklabel that would have been written will be printed to stdout. 430.Pp 431.Nm 432.Fl R 433.Fl B 434.Op Fl n 435.Oo 436.Fl b Ar boot1 437.Fl s Ar boot2 438.Oc 439.Ar disk Ar protofile 440.Oo Ar disktype Ns / Ns Cm auto Oc 441.Pp 442This form corresponds to the 443.Dq restore label 444command described above. 445In addition to restoring the volume label, it also installs the bootstrap. 446If run on the compatibility slice this command will create a 447.Dq dangerously-dedicated 448label. 449This command is normally run on a 450.Bx 451slice rather than the compatibility 452slice. 453.Pp 454The bootstrap commands always access the disk directly, 455so it is not necessary to specify the 456.Fl r 457flag. 458If 459.Fl n 460is used, no data will be written to the device, and instead the 461disklabel that would have been written will be printed to stdout. 462.Pp 463The bootstrap code is comprised of two boot programs. 464Specify the name of the 465boot programs to be installed in one of these ways: 466.Bl -enum 467.It 468Specify the names explicitly with the 469.Fl b 470and 471.Fl s 472flags. 473.Fl b 474indicates the primary boot program and 475.Fl s 476the secondary boot program. 477The boot programs are normally located in 478.Pa /boot . 479.It 480If the 481.Fl b 482and 483.Fl s 484flags are not specified, but 485.Ar disktype 486was specified, the names of the programs are taken from the 487.Dq b0 488and 489.Dq b1 490parameters of the 491.Xr disktab 5 492entry for the disk if the disktab entry exists and includes those parameters. 493.It 494Otherwise, the default boot image names are used: 495.Pa /boot/boot1_64 496and 497.Pa /boot/boot2_64 498for the standard stage1 and stage2 boot images. 499.El 500.Ss Initializing/Formatting a bootable disk from scratch 501To initialize a disk from scratch the following sequence is recommended. 502Please note that this will wipe everything that was previously on the disk, 503including any 504.No non- Ns Dx 505slices. 506.Bl -enum 507.It 508Use 509.Xr gpt 8 510or 511.Xr fdisk 8 512to initialize the hard disk, and create a GPT or MBR slice table, 513referred to as the 514.Dq "partition table" 515in 516.Tn DOS . 517.It 518Use 519.Nm 520or 521.Xr disklabel32 8 522to define partitions on 523.Dx 524slices created in the previous step. 525.It 526Finally use 527.Xr newfs_hammer 8 528or 529.Xr newfs 8 530to create file systems on new partitions. 531.El 532.Pp 533A typical partitioning scheme would be to have an 534.Ql a 535partition 536of approximately 512MB to hold the root file system, a 537.Ql b 538partition for 539swap (usually 4GB), a 540.Ql d 541partition for 542.Pa /var 543(usually 2GB), an 544.Ql e 545partition for 546.Pa /var/tmp 547(usually 2GB), an 548.Ql f 549partition for 550.Pa /usr 551(usually around 4GB), 552and finally a 553.Ql g 554partition for 555.Pa /home 556(usually all remaining space). 557If you are tight on space all sizes can be halved. 558Your mileage may vary. 559.Pp 560.Dl "gpt create da0" 561.Dl "gpt add da0" 562.Dl "disklabel64 -B -r -w da0s0 auto" 563.Dl "disklabel64 -e da0s0" 564.Sh ALIGNMENT 565When a virgin disklabel64 is laid down a 566.Dx 2.5 567or later kernel will align the partition start offset relative to the 568physical drive instead of relative to the slice start. 569This overcomes the issue of fdisk creating a badly aligned slice by default. 570The kernel will use a 1MiB (1024 * 1024 byte) alignment. 571The purpose of this alignment is to match swap and cluster operations 572against the physical block size of the underlying device. 573.Pp 574Even though nearly all devices still report a logical sector size of 512, 575newer hard drives are starting to use larger physical sector sizes 576and, in particular, solid state drives (SSDs) use a physical block size 577of 64K (SLC) or 128K (MLC). We choose a 1 megabyte alignment to cover our 578bases down the road. 64-bit disklabels are not designed to be put on 579ultra-tiny storage devices. 580.Pp 581It is worth noting that aligning cluster operations is particularly 582important for SSDs and doubly so when 583.Xr swapcache 8 584is used with a SSD. 585Swapcache is able to use large bulk writes which greatly reduces the degree 586of write magnification on SSD media and it is possible to get upwards of 5875x more endurance out of the device than the vendor spec sheet indicates. 588.Sh FILES 589.Bl -tag -width ".Pa /boot/boot2_64" -compact 590.It Pa /boot/boot1_64 591Default stage1 boot image. 592.It Pa /boot/boot2_64 593Default stage2 boot image. 594.It Pa /etc/disktab 595Disk description file. 596.El 597.Sh SAVED FILE FORMAT 598The 599.Nm 600utility uses an 601.Tn ASCII 602version of the label when examining, editing, or restoring a disk label. 603The format is: 604.Bd -literal -offset 4n 605# /dev/ad4s4: 606# 607# Informational fields calculated from the above 608# All byte equivalent offsets must be aligned 609# 610# boot space: 32768 bytes 611# data space: 121790552 blocks # 118936.09 MB (124713525248 bytes) 612# 613diskid: 5e3ef4db-4e24-11dd-8318-010e0cd0bad1 614label: 615boot2 data base: 0x000000001000 616partitions data base: 0x000000009000 617partitions data stop: 0x001d0981f000 618backup label: 0x001d0981f000 619total size: 0x001d09820000 # 118936.12 MB 620alignment: 4096 621display block size: 1024 # for partition display only 622 62316 partitions: 624# size offset fstype fsuuid 625 a: 524288 0 4.2BSD # 512.000MB 626 b: 4194304 524288 swap # 4096.000MB 627 d: 2097152 4718592 4.2BSD # 2048.000MB 628 e: 2097152 6815744 4.2BSD # 2048.000MB 629 f: 4194304 8912896 4.2BSD # 4096.000MB 630 g: 4194304 13107200 4.2BSD # 4096.000MB 631 h: 94003288 17301504 HAMMER # 91800.086MB 632 i: 5242880 111304792 ccd # 5120.000MB 633 j: 5242880 116547672 vinum # 5120.000MB 634 a-stor_uuid: 4370efdb-4e25-11dd-8318-010e0cd0bad1 635 b-stor_uuid: 4370eff4-4e25-11dd-8318-010e0cd0bad1 636 d-stor_uuid: 4370f00b-4e25-11dd-8318-010e0cd0bad1 637 e-stor_uuid: 4370f024-4e25-11dd-8318-010e0cd0bad1 638 f-stor_uuid: 4370f03a-4e25-11dd-8318-010e0cd0bad1 639 g-stor_uuid: 4370f053-4e25-11dd-8318-010e0cd0bad1 640 h-stor_uuid: 4370f06a-4e25-11dd-8318-010e0cd0bad1 641 i-stor_uuid: 4370f083-4e25-11dd-8318-010e0cd0bad1 642 j-stor_uuid: 4370f099-4e25-11dd-8318-010e0cd0bad1 643.Ed 644.Pp 645Lines starting with a 646.Ql # 647mark are comments. 648The specifications which can be changed are: 649.Bl -inset 650.It Ar label 651is an optional label, set by the 652.Ar packid 653option when writing a label. 654.It Ar "the partition table" 655is the 656.Ux 657partition table, not the 658.Tn DOS 659partition table described in 660.Xr fdisk 8 . 661.El 662.Pp 663The partition table can have up to 16 entries. 664It contains the following information: 665.Bl -tag -width indent 666.It Ar # 667The partition identifier is a single letter in the range 668.Ql a 669to 670.Ql p . 671.It Ar size 672The size of the partition in sectors, 673.Cm K 674(kilobytes - 1024), 675.Cm M 676(megabytes - 1024*1024), 677.Cm G 678(gigabytes - 1024*1024*1024), 679.Cm % 680(percentage of free space 681.Em after 682removing any fixed-size partitions), 683.Cm * 684(all remaining free space 685.Em after 686fixed-size and percentage partitions). 687Lowercase versions of 688.Cm K , M , 689and 690.Cm G 691are allowed. 692Size and type should be specified without any spaces between them. 693.Pp 694Example: 2097152, 1G, 1024M and 1048576K are all the same size 695(assuming 512-byte sectors). 696.It Ar offset 697The offset of the start of the partition from the beginning of the 698drive in sectors, or 699.Cm * 700to have 701.Nm 702calculate the correct offset to use (the end of the previous partition plus 703one. 704.It Ar fstype 705Describes the purpose of the partition. 706The example shows all currently used partition types. 707For 708.Xr UFS 5 709file systems, use type 710.Cm 4.2BSD . 711For 712.Xr HAMMER 5 713file systems, use type 714.Cm HAMMER . 715For 716.Xr ccd 4 717partitions, use type 718.Cm ccd . 719For Vinum drives, use type 720.Cm vinum . 721Other common types are 722.Cm swap 723and 724.Cm unused . 725The 726.Nm 727utility 728also knows about a number of other partition types, 729none of which are in current use. 730(See 731.Dv fstypenames 732in 733.In sys/dtype.h 734for more details). 735.El 736.Pp 737The remainder of the line is a comment and shows the size of 738the partition in MB. 739.Sh EXAMPLES 740.Dl "disklabel64 da0s1" 741.Pp 742Display the in-core label for the first slice of the 743.Pa da0 744disk, as obtained via 745.Pa /dev/da0s1 . 746(If the disk is 747.Dq dangerously-dedicated , 748the compatibility slice name should be specified, such as 749.Pa da0s0 . ) 750.Pp 751.Dl "disklabel64 da0s1 > savedlabel" 752.Pp 753Save the in-core label for 754.Pa da0s1 755into the file 756.Pa savedlabel . 757This file can be used with the 758.Fl R 759option to restore the label at a later date. 760.Pp 761.Dl "disklabel64 -w -r /dev/da0s1 da2212 foo" 762.Pp 763Create a label for 764.Pa da0s1 765based on information for 766.Dq da2212 767found in 768.Pa /etc/disktab . 769Any existing bootstrap code will be clobbered 770and the disk rendered unbootable. 771.Pp 772.Dl "disklabel64 -e -r da0s1" 773.Pp 774Read the on-disk label for 775.Pa da0s1 , 776edit it, and reinstall in-core as well as on-disk. 777Existing bootstrap code is unaffected. 778.Pp 779.Dl "disklabel64 -e -r -n da0s1" 780.Pp 781Read the on-disk label for 782.Pa da0s1 , 783edit it, and display what the new label would be (in sectors). 784It does 785.Em not 786install the new label either in-core or on-disk. 787.Pp 788.Dl "disklabel64 -r -w da0s1 auto" 789.Pp 790Try to auto-detect the required information from 791.Pa da0s1 , 792and write a new label to the disk. 793Use another 794.Nm Fl e 795command to edit the partitioning information. 796.Pp 797.Dl "disklabel64 -R da0s1 savedlabel" 798.Pp 799Restore the on-disk and in-core label for 800.Pa da0s1 801from information in 802.Pa savedlabel . 803Existing bootstrap code is unaffected. 804.Pp 805.Dl "disklabel64 -R -n da0s1 label_layout" 806.Pp 807Display what the label would be for 808.Pa da0s1 809using the partition layout in 810.Pa label_layout . 811This is useful for determining how much space would be allotted for various 812partitions with a labelling scheme using 813.Cm % Ns -based 814or 815.Cm * 816partition sizes. 817.Pp 818.Dl "disklabel64 -B da0s1" 819.Pp 820Install a new bootstrap on 821.Pa da0s1 . 822The boot code comes from 823.Pa /boot/boot1_64 824and possibly 825.Pa /boot/boot2_64 . 826On-disk and in-core labels are unchanged. 827.Pp 828.Dl "disklabel64 -w -B /dev/da0s1 -b newboot1 -s newboot2 da2212" 829.Pp 830Install a new label and bootstrap. 831The label is derived from disktab information for 832.Dq da2212 833and installed both in-core and on-disk. 834The bootstrap code comes from the files 835.Pa newboot1 836and 837.Pa newboot2 . 838.Pp 839.Dl "dd if=/dev/zero of=/dev/da0 bs=512 count=32" 840.Dl "fdisk -BI da0" 841.Dl "dd if=/dev/zero of=/dev/da0s1 bs=512 count=32" 842.Dl "disklabel64 -w -B da0s1 auto" 843.Dl "disklabel64 -e da0s1" 844.Pp 845Completely wipe any prior information on the disk, creating a new bootable 846disk with a DOS partition table containing one 847.Dq whole-disk 848slice. 849Then 850initialize the slice, then edit it to your needs. 851The 852.Pa dd 853commands are optional, but may be necessary for some BIOSes to properly 854recognize the disk. 855.Pp 856.Dl "disklabel64 -W da0s1" 857.Dl "dd if=/dev/zero of=/dev/da0s1 bs=512 count=32" 858.Dl "disklabel -r -w da0s1 auto" 859.Dl "disklabel -N da0s1" 860.Pp 861Completely wipe any prior information on the slice, 862changing label format to 32 bit. 863The wiping is needed as 864.Nm disklabel 865and 866.Nm , 867as a safety measure, 868won't do any operations if label with other format is already installed. 869.Pp 870This is an example disklabel that uses some of the new partition size types 871such as 872.Cm % , M , G , 873and 874.Cm * , 875which could be used as a source file for 876.Pp 877.Dl "disklabel64 -R ad0s1 new_label_file" 878.Bd -literal -offset 4n 879# /dev/ad4s4: 880# 881# Informational fields calculated from the above 882# All byte equivalent offsets must be aligned 883# 884# boot space: 32768 bytes 885# data space: 121790552 blocks # 118936.09 MB (124713525248 bytes) 886# 887diskid: b1db58a3-4e26-11dd-8318-010e0cd0bad1 888label: 889boot2 data base: 0x000000001000 890partitions data base: 0x000000009000 891partitions data stop: 0x001d0981f000 892backup label: 0x001d0981f000 893total size: 0x001d09820000 # 118936.12 MB 894alignment: 4096 895display block size: 1024 # for partition display only 896 89716 partitions: 898# size offset fstype fsuuid 899 a: 512M 0 4.2BSD 900 b: 4G * swap 901 d: 2G * 4.2BSD 902 e: 2048M * 4.2BSD 903 f: 4G * 4.2BSD 904 g: 4G * 4.2BSD 905 h: * * HAMMER 906 i: 5g * ccd 907 j: 5120m * vinum 908.Ed 909.Sh DIAGNOSTICS 910The kernel device drivers will not allow the size of a disk partition 911to be decreased or the offset of a partition to be changed while it is open. 912Some device drivers create a label containing only a single large partition 913if a disk is unlabeled; thus, the label must be written to the 914.Ql a 915partition of the disk while it is open. 916This sometimes requires the desired 917label to be set in two steps, the first one creating at least one other 918partition, and the second setting the label on the new partition while 919shrinking the 920.Ql a 921partition. 922.Sh SEE ALSO 923.Xr dd 1 , 924.Xr uuid 3 , 925.Xr ccd 4 , 926.Xr disklabel64 5 , 927.Xr disktab 5 , 928.Xr boot0cfg 8 , 929.Xr diskinfo 8 , 930.Xr disklabel32 8 , 931.Xr fdisk 8 , 932.Xr gpt 8 , 933.Xr newfs 8 , 934.Xr newfs_hammer 8 , 935.Xr vinum 8 936.Sh BUGS 937For the i386 architecture, the primary bootstrap sector contains 938an embedded 939.Em fdisk 940table. 941The 942.Nm 943utility takes care to not clobber it when installing a bootstrap only 944.Pq Fl B , 945or when editing an existing label 946.Pq Fl e , 947but it unconditionally writes the primary bootstrap program onto 948the disk for 949.Fl w 950or 951.Fl R , 952thus replacing the 953.Em fdisk 954table by the dummy one in the bootstrap program. 955This is only of 956concern if the disk is fully dedicated, so that the 957.Bx 958disklabel 959starts at absolute block 0 on the disk. 960.Pp 961The 962.Nm 963utility 964does not perform all possible error checking. 965Warning 966.Em is 967given if partitions 968overlap; if an absolute offset does not match the expected offset; if a 969partition runs past the end of the device; and a number of other errors; but 970no warning is given if space remains unused. 971