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 acknowledgement: 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.\" 37.Dd "April 19, 1994" 38.Dt DISKLABEL 8 39.Os BSD 4.2 40.Sh NAME 41.Nm disklabel 42.Nd read and write disk pack label 43.Sh SYNOPSIS 44.Nm disklabel 45.Op Fl r 46.Ar disk 47.Nm disklabel 48.Fl w 49.Op Fl r 50.Ar disk Ar disktype 51.Oo Ar packid Oc 52.Nm disklabel 53.Fl e 54.Op Fl r 55.Ar disk 56.Nm disklabel 57.Fl R 58.Op Fl r 59.Ar disk Ar protofile 60.Nm disklabel 61.Op Fl NW 62.Ar disk 63.sp 64.Nm disklabel 65.Fl B 66.Oo 67.Fl b Ar boot1 68.Op Fl s Ar boot2 69.Oc 70.Ar disk 71.Oo Ar disktype Oc 72.Nm disklabel 73.Fl w 74.Fl B 75.Oo 76.Fl b Ar boot1 77.Op Fl s Ar boot2 78.Oc 79.Ar disk Ar disktype 80.Oo Ar packid Oc 81.Nm disklabel 82.Fl R 83.Fl B 84.Oo 85.Fl b Ar boot1 86.Op Fl s Ar boot2 87.Oc 88.Ar disk Ar protofile 89.Oo Ar disktype Oc 90.Sh DESCRIPTION 91.Nm Disklabel 92can be used to install, examine or modify the label on a disk drive or pack. 93When writing the label, it can be used 94to change the drive identification, 95the disk partitions on the drive, 96or to replace a damaged label. 97On some systems, 98.Nm disklabel 99can be used to install bootstrap code as well. 100There are several forms of the command that read (display), install or edit 101the label on a disk. 102Each form has an additional option, 103.Fl r , 104which causes the label to be read from or written to the disk directly, 105rather than going through the system's in-core copy of the label. 106This option may allow a label to be installed on a disk 107without kernel support for a label, such as when labels are first installed 108on a system; it must be used when first installing a label on a disk. 109The specific effect of 110.Fl r 111is described under each command. 112The read and install forms also support the 113.Fl B 114option to install bootstrap code. 115These variants are described later. 116.Pp 117The first form of the command (read) is used to examine the label on the named 118disk drive (e.g. sd0 or /dev/rsd0c). 119It will display all of the parameters associated with the drive 120and its partition layout. 121Unless the 122.Fl r 123flag is given, 124the kernel's in-core copy of the label is displayed; 125if the disk has no label, or the partition types on the disk are incorrect, 126the kernel may have constructed or modified the label. 127If the 128.Fl r 129flag is given, the label from the raw disk will be displayed rather 130than the in-core label. 131.Pp 132The second form of the command, with the 133.Fl w 134flag, is used to write a standard label on the designated drive. 135The required arguments to 136.Nm disklabel 137are the drive to be labelled (e.g. sd0), and 138the drive type as described in the 139.Xr disktab 5 140file. 141The drive parameters and partitions are taken from that file. 142If different disks of the same physical type are to have different 143partitions, it will be necessary to have separate disktab entries 144describing each, or to edit the label after installation as described below. 145The optional argument is a pack identification string, 146up to 16 characters long. 147The pack id must be quoted if it contains blanks. 148If the 149.Fl r 150flag is given, the disk sectors containing the label and bootstrap 151will be written directly. 152A side-effect of this is that any existing bootstrap code will be overwritten 153and the disk rendered unbootable. 154If 155.Fl r 156is not specified, 157the existing label will be updated via the in-core copy and any bootstrap 158code will be unaffected. 159If the disk does not already have a label, the 160.Fl r 161flag must be used. 162In either case, the kernel's in-core label is replaced. 163.Pp 164For a virgin disk that is not known to 165.Xr disktab 5 , 166.Ar disktype 167can be specified as 168.Dq auto . 169In this case, the driver is requested to produce a virgin label for the 170disk. This might or might not be successful, depending on whether the 171driver for the disk is able to get the required data without reading 172anything from the disk at all. It will likely succeed for all SCSI 173disks, most IDE disks, and vnode devices. Writing a label to the 174disk is the only supported operation, and the 175.Ar disk 176itself must be provided as the canonical name, i.e. not as a full 177path name. 178.Pp 179An existing disk label may be edited by using the 180.Fl e 181flag. 182The label is read from the in-core kernel copy, 183or directly from the disk if the 184.Fl r 185flag is also given. 186The label is formatted and then supplied to an editor for changes. 187If no editor is specified in an 188.Ev EDITOR 189environment variable, 190.Xr vi 1 191is used. 192When the editor terminates, the formatted label is reread 193and used to rewrite the disk label. 194Existing bootstrap code is unchanged regardless of whether 195.Fl r 196was specified. 197.Pp 198With the 199.Fl R 200flag, 201.Nm disklabel 202is capable of restoring a disk label that was formatted 203in a prior operation and saved in an ascii file. 204The prototype file used to create the label should be in the same format 205as that produced when reading or editing a label. 206Comments are delimited by 207.Ar \&# 208and newline. 209As with 210.Fl w , 211any existing bootstrap code will be clobbered if 212.Fl r 213is specified and will be unaffected otherwise. 214.Pp 215The 216.Fl NW 217flags for 218.Nm disklabel 219explicitly disallow and 220allow, respectively, writing of the pack label area on the selected disk. 221.Pp 222The final three forms of 223.Nm disklabel 224are used to install boostrap code on machines where the bootstrap is part 225of the label. 226The bootstrap code is comprised of one or two boot programs depending on 227the machine. 228The 229.Fl B 230option is used to denote that bootstrap code is to be installed. 231The 232.Fl r 233flag is implied by 234.Fl B 235and never needs to be specified. 236The name of the boot program(s) to be installed can be selected in a 237variety of ways. 238First, the names can be specified explicitly via the 239.Fl b 240and 241.Fl s 242flags. 243On machines with only a single level of boot program, 244.Fl b 245is the name of that program. 246For machines with a two-level bootstrap, 247.Fl b 248indicates the primary boot program and 249.Fl s 250the secondary boot program. 251If the names are not explicitly given, standard boot programs will be used. 252The boot programs are located in 253.Pa /usr/mdec . 254The names of the programs are taken from the ``b0'' and ``b1'' parameters 255of the 256.Xr disktab 5 257entry for the disk if 258.Ar disktype 259was given and its disktab entry exists and includes those parameters. 260Otherwise, boot program names are derived from the name of the disk. 261These names are of the form 262.Pa basename Ns boot 263for the primary (or only) bootstrap, and 264.Pf boot Pa basename 265for the secondary bootstrap; 266for example, 267.Pa /usr/mdec/sdboot 268and 269.Pa /usr/mdec/bootsd 270if the disk device is 271.Em sd0 . 272.Pp 273The first of the three boot-installation forms is used to install 274bootstrap code without changing the existing label. 275It is essentially a read command with respect to the disk label 276itself and all options are related to the specification of the boot 277program as described previously. 278The final two forms are analogous to the basic write and restore versions 279except that they will install bootstrap code in addition to a new label. 280.Sh FILES 281.Bl -tag -width Pa -compact 282.It Pa /etc/disktab 283.It Pa /usr/mdec/ Ns Em xx Ns boot 284.It Pa /usr/mdec/boot Ns Em xx 285.El 286.Sh EXAMPLES 287.Dl disklabel sd0 288.Pp 289Display the in-core label for sd0 as obtained via 290.Pa /dev/rsd0c . 291.Pp 292.Dl disklabel -w -r /dev/rsd0c sd2212 foo 293.Pp 294Create a label for sd0 based on information for ``sd2212'' found in 295.Pa /etc/disktab . 296Any existing bootstrap code will be clobbered. 297.Pp 298.Dl disklabel -e -r sd0 299.Pp 300Read the on-disk label for sd0, edit it and reinstall in-core as well 301as on-disk. 302Existing bootstrap code is unaffected. 303.Pp 304.Dl disklabel -r -w sd0 auto 305.Pp 306Try to auto-detect the required information from sd0, and write a new 307label to the disk. Use another disklabel -e command to edit the 308partitioning and file system information. 309.Pp 310.Dl disklabel -R sd0 mylabel 311.Pp 312Restore the on-disk and in-core label for sd0 from information in 313.Pa mylabel . 314Existing bootstrap code is unaffected. 315.Pp 316.Dl disklabel -B sd0 317.Pp 318Install a new bootstrap on sd0. 319The boot code comes from 320.Pa /usr/mdec/sdboot 321and possibly 322.Pa /usr/mdec/bootsd . 323On-disk and in-core labels are unchanged. 324.Pp 325.Dl disklabel -w -B /dev/rsd0c -b newboot sd2212 326.Pp 327Install a new label and bootstrap. 328The label is derived from disktab information for ``sd2212'' and 329installed both in-core and on-disk. 330The bootstrap code comes from the file 331.Pa /usr/mdec/newboot . 332.Sh SEE ALSO 333.Xr disktab 5 , 334.Xr disklabel 5 335.Sh DIAGNOSTICS 336The kernel device drivers will not allow the size of a disk partition 337to be decreased or the offset of a partition to be changed while it is open. 338Some device drivers create a label containing only a single large partition 339if a disk is unlabeled; thus, the label must be written to the ``a'' 340partition of the disk while it is open. 341This sometimes requires the desired label to be set in two steps, 342the first one creating at least one other partition, 343and the second setting the label on the new partition 344while shrinking the ``a'' partition. 345.Pp 346On some machines the bootstrap code may not fit entirely in the area 347allocated for it by some filesystems. 348As a result, it may not be possible to have filesystems on some partitions 349of a ``bootable'' disk. 350When installing bootstrap code, 351.Nm disklabel 352checks for these cases. 353If the installed boot code would overlap a partition of type FS_UNUSED 354it is marked as type FS_BOOT. 355The 356.Xr newfs 8 357utility will disallow creation of filesystems on FS_BOOT partitions. 358Conversely, if a partition has a type other than FS_UNUSED or FS_BOOT, 359.Nm disklabel 360will not install bootstrap code that overlaps it. 361.Sh BUGS 362When a disk name is given without a full pathname, 363the constructed device name uses the ``a'' partition on the tahoe, 364the ``c'' partition on all others. 365.Pp 366For the i386 architecture, the primary bootstrap sector contains 367an embedded 368.Em fdisk 369table. 370.Nm Disklabel 371takes care to not clobber it when installing a bootstrap only 372.Pq Fl B , 373or when editing an existing label 374.Pq Fl e , 375but it unconditionally writes the primary bootstrap program onto 376the disk for 377.Fl w 378or 379.Fl R , 380thus replacing the 381.Em fdisk 382table by the dummy one in the bootstrap program. This is only of 383concern if the disk is fully dedicated, so that the BSD disklabel 384starts at absolute block 0 on the disk. 385