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.\" $FreeBSD$ 37.\" 38.Dd July 30, 1999 39.Dt DISKLABEL 8 40.Os 41.Sh NAME 42.Nm disklabel 43.Nd read and write disk pack label 44.Sh SYNOPSIS 45.Nm 46.Op Fl r 47.Ar disk 48.Nm 49.Fl w 50.Op Fl r 51.Op Fl n 52.Ar disk Ar disktype/auto 53.Oo Ar packid Oc 54.Nm 55.Fl e 56.Op Fl r 57.Op Fl n 58.Ar disk 59.Nm 60.Fl R 61.Op Fl r 62.Op Fl n 63.Ar disk Ar protofile 64.Nm 65.Op Fl NW 66.Ar disk 67.Pp 68.Nm 69.Fl B 70.Oo 71.Fl b Ar boot1 72.Fl s Ar boot2 73.Oc 74.Ar disk 75.Oo Ar disktype/auto Oc 76.Nm 77.Fl w 78.Fl B 79.Op Fl n 80.Oo 81.Fl b Ar boot1 82.Fl s Ar boot2 83.Oc 84.Ar disk Ar disktype/auto 85.Oo Ar packid Oc 86.Nm 87.Fl R 88.Fl B 89.Op Fl n 90.Oo 91.Fl b Ar boot1 92.Fl s Ar boot2 93.Oc 94.Ar disk Ar protofile 95.Oo Ar disktype/auto Oc 96.Sh DESCRIPTION 97.Nm Disklabel 98installs, examines or modifies the label on a disk drive or pack. When writing 99the label, it can be used to change the drive identification, the disk 100partitions on the drive, or to replace a damaged label. There are several forms 101of the command that read (display), install or edit the label on a disk. In 102addition, 103.Nm 104can install bootstrap code. 105.Ss Raw or in-core label 106.Pp 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. By 109default, most 110.Nm 111access the in-core copy of the label. To access the raw (on-disk) copy, use the 112.Fl r 113option. This option allows a label to be installed on a disk without kernel 114support for a label, such as when labels are first installed on a system; it 115must be used when first installing a label on a disk. The specific effect of 116.Fl r 117is described under each command. 118.Pp 119.Ss Disk device name 120.Pp 121All 122.Nm 123forms require a disk device name, which should always be the raw 124device name representing the disk or slice. For example 125.Pa da0 126represents the entire disk regardless of any DOS partitioning, 127and 128.Pa da0s1 129represents a slice. Some devices, most notably 130.Ar ccd , 131require that the 132.Dq whole-disk 133(or 134.Dq c ) 135partition be specified. For example 136.Pa ccd0c . 137You do not have to include the 138.Pa /dev/ 139path prefix when specifying the device. 140.Nm 141will automatically prepend it. 142.Ss Reading the disk label 143.Pp 144To examine the label on a disk drive, use 145.Nm 146without options: 147.Pp 148.Nm 149.Op Fl r 150.Ar disk 151.Pp 152.Ar disk 153represents the raw disk in question, and may be in the form 154.Pa da0 155or 156.Pa /dev/da0c . 157It will display all of the parameters associated with the drive and its 158partition layout. Unless the 159.Fl r 160flag is given, 161the kernel's in-core copy of the label is displayed; 162if the disk has no label, or the partition types on the disk are incorrect, 163the kernel may have constructed or modified the label. 164If the 165.Fl r 166flag is given, 167.Nm 168reads the label from the raw disk and displays it. Both versions are usually 169identical except in the case where a label has not yet been initialized or 170is corrupt. 171.Ss Writing a standard label 172.Pp 173To write a standard label, use the form 174.Pp 175.Nm 176.Fl w 177.Op Fl r 178.Op Fl n 179.Ar disk Ar disktype/auto 180.Oo Ar packid Oc 181.Pp 182.Nm 183.Fl w 184.Op Fl r 185.Op Fl n 186.Ar disk 187auto 188.Pp 189The required arguments to 190.Nm 191are the drive to be labeled and the drive type as described in the 192.Xr disktab 5 193file. The drive parameters and partitions are taken from that file. If 194different disks of the same physical type are to have different partitions, it 195will be necessary to have separate disktab entries describing each, or to edit 196the label after installation as described below. The optional argument is a 197pack identification string, up to 16 characters long. The pack id must be 198quoted if it contains blanks. 199.Pp 200If the 201.Fl n 202flag is given, no data will be written to the device, and instead the 203disklabel that would have been written will be printed to stdout. 204.Pp 205If the 206.Fl r 207flag is given, the disk sectors containing the label and bootstrap 208will be written directly. 209A side-effect of this is that any existing bootstrap code will be overwritten 210and the disk rendered unbootable. See the boot options below for a method of 211writing the label and the bootstrap at the same time. 212If 213.Fl r 214is not specified, 215the existing label will be updated via the in-core copy and any bootstrap 216code will be unaffected. 217If the disk does not already have a label, the 218.Fl r 219flag must be used. 220In either case, the kernel's in-core label is replaced. 221.Pp 222For a virgin disk that is not known to 223.Xr disktab 5 , 224.Ar disktype 225can be specified as 226.Dq auto . 227In this case, the driver is requested to produce a virgin label for the 228disk. This might or might not be successful, depending on whether the 229driver for the disk is able to get the required data without reading 230anything from the disk at all. It will likely succeed for all SCSI 231disks, most IDE disks, and vnode devices. Writing a label to the 232disk is the only supported operation, and the 233.Ar disk 234itself must be provided as the canonical name, i.e. not as a full 235path name. 236.Pp 237For most harddisks, a label based on percentages for most partitions (and 238one partition with a size of 239.Ql * ) 240will produce a reasonable configuration. 241.Pp 242PC-based systems have special requirements in order for the BIOS to properly 243recognize a 244.Fx 245disklabel. Older systems may require what is known as a 246.Dq dangerously dedicated 247disklabel, which creates a fake DOS partition to work around problems older 248BIOSes have with modern disk geometries. 249On newer systems you generally want 250to create a normal DOS partition using 251.Ar fdisk 252and then create a 253.Fx 254disklabel within that slice. This is described 255later on in this page. 256.Pp 257Installing a new disklabel does not in of itself allow your system to boot 258a kernel using that label. You must also install boot blocks, which is 259described later on in this manual page. 260.Ss Editing an existing disk label 261.Pp 262To edit an existing disk label, use the form 263.Pp 264.Nm 265.Fl e 266.Op Fl r 267.Op Fl n 268.Ar disk 269.Pp 270This command reads the label from the in-core kernel copy, or directly from the 271disk if the 272.Fl r 273flag is also specified. The label is written to a file in ASCII and then 274supplied to an editor for changes. If no editor is specified in an 275.Ev EDITOR 276environment variable, 277.Xr vi 1 278is used. When the editor terminates, the label file is used to rewrite the disk 279label. Existing bootstrap code is unchanged regardless of whether 280.Fl r 281was specified. If 282.Fl n 283is specified, no data will be written to the device, and instead the 284disklabel that would have been written will be printed to stdout. This is 285useful to see how a partitioning scheme will work out for a specific disk. 286.Ss Restoring a disk label from a file 287.Pp 288To restore a disk label from a file, use the form 289.Pp 290.Nm 291.Fl R 292.Op Fl r 293.Op Fl n 294.Ar disk Ar protofile 295.Pp 296.Nm 297is capable of restoring a disk label that was previously saved in a file in ASCII format. 298The prototype file used to create the label should be in the same format as that 299produced when reading or editing a label. Comments are delimited by 300.Ar \&# 301and newline. As when writing a new label, any existing bootstrap code will be 302clobbered if 303.Fl r 304is specified and will be unaffected otherwise. See the boot options below for a 305method of restoring the label and writing the bootstrap at the same time. 306If 307.Fl n 308is used, no data will be written to the device, and instead the 309disklabel that would have been written will be printed to stdout. This is 310useful to see how a partitioning scheme will work out for a specific disk. 311.Ss Enabling and disabling writing to the disk label area 312.Pp 313By default, it is not possible to write to the disk label area at the beginning 314of a disk. The disk driver silently ignores any attempt to do so. If you need 315to write to this area (for example, to obliterate the label), use the form 316.Pp 317.Nm 318.Fl W 319.Ar disk 320.Pp 321To disallow writing to the label area after previously allowing it, use the 322command 323.Pp 324.Nm 325.Fl N 326.Ar disk 327.Ss Installing bootstraps 328.Pp 329The final three forms of 330.Nm 331are used to install bootstrap code. If you are creating a 332.Dq dangerously-dedicated 333slice for compatibility with older PC systems, 334you generally want to specify the raw disk name such as 335.Pa da0 . 336If you are creating a label within an existing DOS slice, 337you should specify 338the partition name such as 339.Pa da0s1a . 340Making a slice bootable can be tricky. If you are using a normal DOS 341slice you typically install (or leave) a standard MBR on the base disk and 342then install the 343.Fx 344bootblocks in the slice. 345.Pp 346.Nm 347.Fl B 348.Oo 349.Fl b Ar boot1 350.Fl s Ar boot2 351.Oc 352.Ar disk 353.Oo Ar disktype Oc 354.Pp 355This form installs the bootstrap only. It does not change the disk label. 356You should never use this command on a base disk unless you intend to create a 357.Dq dangerously-dedicated 358disk, such as 359.Ar da0 . 360This command is typically run on a slice such as 361.Ar da0s1 . 362.Pp 363.Nm 364.Fl w 365.Fl B 366.Op Fl n 367.Oo 368.Fl b Ar boot1 369.Fl s Ar boot2 370.Oc 371.Ar disk Ar disktype 372.Oo Ar packid Oc 373.Pp 374This form corresponds to the 375.Dq write label 376command described above. 377In addition to writing a new volume label, it also installs the bootstrap. 378If run on a base disk this command will create a 379.Dq dangerously-dedicated 380label. This command is normally run on a slice rather than a base disk. 381If 382.Fl n 383is used, no data will be written to the device, and instead the 384disklabel that would have been written will be printed to stdout. 385.Pp 386.Nm 387.Fl R 388.Fl B 389.Op Fl n 390.Oo 391.Fl b Ar boot1 392.Fl s Ar boot2 393.Oc 394.Ar disk Ar protofile 395.Oo Ar disktype Oc 396.Pp 397This form corresponds to the 398.Dq restore label 399command described above. 400In addition to restoring the volume label, it also installs the bootstrap. 401If run on a base disk this command will create a 402.Dq dangerously-dedicated 403label. This command is normally run on a slice rather than a base disk. 404.Pp 405The bootstrap commands always access the disk directly, so it is not necessary 406to specify the 407.Fl r 408flag. If 409.Fl n 410is used, no data will be written to the device, and instead the 411disklabel that would have been written will be printed to stdout. 412.Pp 413The bootstrap code is comprised of two boot programs. Specify the name of the 414boot programs to be installed in one of these ways: 415.Bl -enum 416.It 417Specify the names explicitly with the 418.Fl b 419and 420.Fl s 421flags. 422.Fl b 423indicates the primary boot program and 424.Fl s 425the secondary boot program. The boot programs are located in 426.Pa /boot . 427.It 428If the 429.Fl b 430and 431.Fl s 432flags are not specified, but 433.Ar disktype 434was specified, the names of the programs are taken from the 435.Dq b0 436and 437.Dq b1 438parameters of the 439.Xr disktab 5 440entry for the disk if the disktab entry exists and includes those parameters. 441.It 442Otherwise, the default boot image names are used: 443.Pa /boot/boot1 444and 445.Pa /boot/boot2 446for the standard stage1 and stage2 boot images (details may vary 447on architectures like the Alpha, where only a single-stage boot is used). 448.El 449.Ss Initializing/Formatting a bootable disk from scratch 450.Pp 451To initialize a disk from scratch the following sequence is recommended. 452Please note that this will wipe everything that was previously on the disk, 453including any 454.No non- Ns Fx 455slices. 456.Bl -enum 457.It 458Use 459.Xr fdisk 8 460to initialize the hard disk, and create a slice table, referred to 461as the partition table in DOS. 462Here you will define disk slices for your system. 463.It 464Use 465.Xr disklabel 8 466to define and write partitions and mount points. 467You are not required to define the mount points here though, 468they can be defined later using 469.Xr mount 8 . 470.It 471Finally use 472.Xr newfs 8 473to create a filesystem on the new partition. 474A typical partitioning scheme would be to have an 475.Dq a 476partition 477of approximately 128MB to hold the root filesystem, a 478.Dq b 479partition for 480swap, a 481.Dq d 482partition for /var (usually 128MB), an 483.Dq e 484partition 485for /var/tmp (usually 128MB), an 486.Dq f 487partition for /usr (usually around 2G), 488and finally a 489.Dq g 490partition for /home (usually all remaining space). 491Your mileage may vary. 492.El 493.Pp 494.Nm fdisk Fl BI Ar da0 495.Pp 496.Nm 497.Fl w 498.Fl B 499.Ar da0s1 500auto 501.Pp 502.Pp 503.Nm 504.Fl e 505.Ar da0s1 506.Sh FILES 507.Bl -tag -width Pa -compact 508.It Pa /etc/disktab 509.It Pa /boot/ 510.It Pa /boot/boot<n> 511.El 512.Sh SAVED FILE FORMAT 513.Nm 514uses an ASCII version of the label when examining, editing or restoring a disk 515label. The format is: 516.Bd -literal -offset 4n 517# /dev/da1c: 518type: SCSI 519disk: da0s1 520label: 521flags: 522bytes/sector: 512 523sectors/track: 51 524tracks/cylinder: 19 525sectors/cylinder: 969 526cylinders: 1211 527sectors/unit: 1173930 528rpm: 3600 529interleave: 1 530trackskew: 0 531cylinderskew: 0 532headswitch: 0 # milliseconds 533track-to-track seek: 0 # milliseconds 534drivedata: 0 535 5368 partitions: 537# size offset fstype [fsize bsize bps/cpg] 538 a: 81920 0 4.2BSD 1024 8192 16 # (Cyl. 0 - 84*) 539 b: 160000 81920 swap # (Cyl. 84* - 218*) 540 c: 1173930 0 unused 0 0 # (Cyl. 0 - 1211*) 541 h: 962010 211920 vinum # (Cyl. 218*- 1211*) 542.Ed 543.Pp 544Lines starting with a # mark are comments. Most of the other specifications are 545no longer used. The ones which must still be set correctly are: 546.Pp 547.Bl -hang -width 20n 548.It Nm label 549is an optional label, set by the 550.Ar packid 551option when writing a label. 552.It Nm flags 553Flags may be 554.Ar removable , 555.Ar ecc 556or 557.Ar badsect . 558.Ar removable 559is set for removable media drives, but no current 560.Fx 561driver evaluates this 562flag. 563.Ar ecc 564is no longer supported; 565.Ar badsect 566specifies that the drive can perform bad sector remapping. 567.It Nm sectors/unit 568describes the total size of the disk. This value must be correct. 569.It Nm the partition table 570This is the 571.Ux 572partition table, not the Microsoft partition table described in 573.Xr fdisk 8 . 574.El 575.Pp 576The partition table can have up to 8 entries. It contains the following 577information: 578.Bl -hang -width 10n 579.It identifier 580The partition identifier is a single letter in the range 581.Dq a 582to 583.Dq h . 584By convention, partition 585.Dq c 586is reserved to describe the entire disk. 587.It size 588is the size of the partition in sectors, 589.Cm K 590(kilobytes - 1024), 591.Cm M 592(megabytes - 1024*1024), 593.Cm G 594(gigabytes - 1024*1024*1024), 595.Cm % 596(percentage of free space AFTER removing any fixed-size partitions other 597than partition 598.Dq c) , 599or 600.Cm * 601(all remaining free space AFTER fixed-size and percentage 602partitions). For partition 603.Dq c , 604a size of 605.Cm * 606indicates the entire disk. Lowercase versions of 607.Cm K , M , 608and 609.Cm G 610are allowed. 611Size and type should be specifed without any spaces between them. 612.Pp 613Example: 2097152, 1g, 1024m and 1048576k are all the same size 614(assuming 512-byte sectors). 615.It offset 616is the offset of the start of the partition from the beginning of the 617drive in sectors, or 618.Cm * 619to have 620.Nm 621calculate the correct offset to use (the end of the previous partition plus 622one, ignoring partition 623.Dq c . 624For partition 625.Dq c , 626.Cm * 627will be interpreted as an offset of 0. 628.It fstype 629describes the purpose of the partition. The example shows all currently used 630partition types. 631For UFS filesystems and ccd partitions, use type 632.Cm 4.2BSD . 633For Vinum drives, use type 634.Cm vinum . 635Other common types are 636.Cm unused 637and 638.Cm swap . 639By convention, partition 640.Dq c 641represents the entire slice and should be of type 642.Cm unused , 643though 644.Nm 645does not enforce this convention. 646.Nm 647also knows about a number of other partition types, none of which are in current 648use. 649See the definitions starting with 650.Dv FS_UNUSED 651in 652.Pa /usr/include/sys/disklabel.h 653for more details. 654.It fsize 655For 656.Cm 4.2BSD 657and LFS filesystems only, the fragment size. Defaults to 1024 for 658partitions smaller than 1 GB, 4096 for partitions 1GB or larger. 659.It bsize 660For 661.Cm 4.2BSD 662and LFS filesystems only, the block size. Defaults to 8192 for 663partitions smaller than 1 GB, 16384 for partitions 1GB or larger. 664.It bps/cpg 665For 666.Cm 4.2BSD 667filesystems, the number of cylinders in a cylinder group. For LFS file 668systems, the segment shift value. Defaults to 16 for 669partitions smaller than 1 GB, 64 for partitions 1GB or larger. 670.El 671.Pp 672The remainder of the line is a comment and shows the cylinder allocations based 673on the obsolete (but possibly correct) geometry information about the drive. 674The asterisk (*) indicates that the partition does not begin or end exactly on a 675cylinder boundary. 676.Sh EXAMPLES 677.Dl disklabel da0 678.Pp 679Display the in-core label for 680.Pa da0s1 681as obtained via 682.Pa /dev/da0s1 . 683When reading a label, 684.Fx 685will allow you to specify the base disk name 686even if the label resides on a slice. However, to be proper you should 687specify the base disk name only if you are using a 688.Dq dangerously-dedicated 689label. Normally you specify the slice. 690.Pp 691.Dl disklabel da0s1 > savedlabel 692.Pp 693Save the in-core label for 694.Pa da0s1 695into the file 696.Pa savedlabel . 697This file can be used with the 698.Fl R 699flag to restore the label at a later date. 700.Pp 701.Dl disklabel -w -r /dev/da0s1 da2212 foo 702.Pp 703Create a label for 704.Pa da0s1 705based on information for 706.Dq da2212 707found in 708.Pa /etc/disktab . 709Any existing bootstrap code will be clobbered. 710.Pp 711.Dl disklabel -e -r da0s1 712.Pp 713Read the on-disk label for 714.Pa da0s1 , 715edit it and reinstall in-core as well as on-disk. Existing bootstrap code is 716unaffected. 717.Pp 718.Dl disklabel -e -r -n da0s1 719.Pp 720Read the on-disk label for 721.Pa da0s1 , 722edit it, and display what the new label would be (in sectors). It does 723NOT install the new label either in-core or on-disk. 724.Pp 725.Dl disklabel -r -w da0s1 auto 726.Pp 727Try to auto-detect the required information from 728.Pa da0s1 , 729and write a new label to the disk. Use another disklabel -e command to edit the 730partitioning and filesystem information. 731.Pp 732.Dl disklabel -R da0s1 savedlabel 733.Pp 734Restore the on-disk and in-core label for 735.Pa da0s1 736from information in 737.Pa savedlabel . 738Existing bootstrap code is unaffected. 739.Pp 740.Dl disklabel -R -n da0s1 label_layout 741.Pp 742Display what the label would be for 743.Pa da0s1 744using the partition layout in 745.Pa label_layout . 746This is useful for determining how much space would be alloted for various 747partitions with a labelling scheme using 748.Cm % Ns -based 749or 750.Cm * 751partition sizes. 752.Pp 753.Dl disklabel -B da0s1 754.Pp 755Install a new bootstrap on 756.Pa da0s1 . 757The boot code comes from 758.Pa /boot/boot1 759and possibly 760.Pa /boot/boot2 . 761On-disk and in-core labels are unchanged. 762.Pp 763.Dl disklabel -w -B /dev/da0s1 -b newboot1 -s newboot2 da2212 764.Pp 765Install a new label and bootstrap. 766The label is derived from disktab information for 767.Dq da2212 768and installed both in-core and on-disk. 769The bootstrap code comes from the files 770.Pa /boot/newboot1 771and 772.Pa /boot/newboot2 . 773.Pp 774.Dl dd if=/dev/zero of=/dev/da0 bs=512 count=32 775.Dl fdisk -BI da0 776.Dl dd if=/dev/zero of=/dev/da0s1 bs=512 count=32 777.Dl disklabel -w -B da0s1 auto 778.Dl disklabel -e da0s1 779.Pp 780Completely wipe any prior information on the disk, creating a new bootable 781disk with a DOS partition table containing one 782.Dq whole-disk 783slice. Then 784initialize the slice, then edit it to your needs. The 785.Pa dd 786commands are optional, but may be necessary for some BIOSes to properly 787recognize the disk. 788.Pp 789This is an example disklabel that uses some of the new partition size types 790such as 791.Cm % , M , G , 792and 793.Cm * , 794which could be used as a source file for 795.Pp 796.Dl disklabel -R ad0s1c new_label_file 797.Bd -literal -offset 4n 798# /dev/ad0s1c: 799type: ESDI 800disk: ad0s1 801label: 802flags: 803bytes/sector: 512 804sectors/track: 63 805tracks/cylinder: 16 806sectors/cylinder: 1008 807cylinders: 40633 808sectors/unit: 40959009 809rpm: 3600 810interleave: 1 811trackskew: 0 812cylinderskew: 0 813headswitch: 0 # milliseconds 814track-to-track seek: 0 # milliseconds 815drivedata: 0 816 8178 partitions: 818# size offset fstype [fsize bsize bps/cpg] 819 a: 400M 0 4.2BSD 4096 16384 75 # (Cyl. 0 - 812*) 820 b: 1G * swap 821 c: * * unused 822 e: 204800 * 4.2BSD 823 f: 5g * 4.2BSD 824 g: * * 4.2BSD 825.Ed 826.Sh SEE ALSO 827.Xr ccd 4 , 828.Xr disklabel 5 , 829.Xr disktab 5 , 830.Xr boot0cfg 8 , 831.Xr fdisk 8 , 832.Xr vinum 8 833.Sh DIAGNOSTICS 834The kernel device drivers will not allow the size of a disk partition 835to be decreased or the offset of a partition to be changed while it is open. 836Some device drivers create a label containing only a single large partition 837if a disk is unlabeled; thus, the label must be written to the 838.Dq a 839partition of the disk while it is open. This sometimes requires the desired 840label to be set in two steps, the first one creating at least one other 841partition, and the second setting the label on the new partition while shrinking 842the 843.Dq a 844partition. 845.Pp 846On some machines the bootstrap code may not fit entirely in the area 847allocated for it by some filesystems. 848As a result, it may not be possible to have filesystems on some partitions 849of a 850.Dq bootable 851disk. 852When installing bootstrap code, 853.Nm 854checks for these cases. 855If the installed boot code would overlap a partition of type FS_UNUSED 856it is marked as type FS_BOOT. 857The 858.Xr newfs 8 859utility will disallow creation of filesystems on FS_BOOT partitions. 860Conversely, if a partition has a type other than FS_UNUSED or FS_BOOT, 861.Nm 862will not install bootstrap code that overlaps it. 863.Sh BUGS 864When a disk name is given without a full pathname, 865the constructed device name uses the 866.Dq c 867partition. 868.Pp 869For the i386 architecture, the primary bootstrap sector contains 870an embedded 871.Em fdisk 872table. 873.Nm Disklabel 874takes care to not clobber it when installing a bootstrap only 875.Pq Fl B , 876or when editing an existing label 877.Pq Fl e , 878but it unconditionally writes the primary bootstrap program onto 879the disk for 880.Fl w 881or 882.Fl R , 883thus replacing the 884.Em fdisk 885table by the dummy one in the bootstrap program. This is only of 886concern if the disk is fully dedicated, so that the 887.Bx 888disklabel 889starts at absolute block 0 on the disk. 890.Pp 891.Nm 892does not perform all possible error checking. Warning *is* given if partitions 893overlap; if an absolute offset does not match the expected offset; if the 894.Dq c 895partition does not start at 0 or does not cover the entire slice; if a 896partition runs past the end of the device; and a number of other errors; but 897no warning is given if space remains unused. 898