727 lines
19 KiB
Groff
727 lines
19 KiB
Groff
.\" Copyright (c) 1987, 1988, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Symmetric Computer Systems.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgment:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)disklabel.8 8.2 (Berkeley) 4/19/94
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.\" $FreeBSD$
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.\"
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.Dd July 30, 1999
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.Dt DISKLABEL 8
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.Os FreeBSD
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.Sh NAME
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.Nm disklabel
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.Nd read and write disk pack label
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.Sh SYNOPSIS
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.Nm
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.Op Fl r
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.Ar disk
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.Nm
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.Fl w
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.Op Fl r
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.Ar disk Ar disktype/auto
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.Oo Ar packid Oc
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.Nm
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.Fl e
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.Op Fl r
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.Ar disk
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.Nm
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.Fl R
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.Op Fl r
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.Ar disk Ar protofile
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.Nm
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.Op Fl NW
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.Ar disk
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.Pp
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.Nm
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.Fl B
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.Oo
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.Fl b Ar boot1
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.Fl s Ar boot2
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.Oc
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.Ar disk
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.Oo Ar disktype/auto Oc
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.Nm
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.Fl w
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.Fl B
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.Oo
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.Fl b Ar boot1
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.Fl s Ar boot2
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.Oc
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.Ar disk Ar disktype/auto
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.Oo Ar packid Oc
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.Nm
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.Fl R
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.Fl B
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.Oo
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.Fl b Ar boot1
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.Fl s Ar boot2
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.Oc
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.Ar disk Ar protofile
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.Oo Ar disktype/auto Oc
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.Sh DESCRIPTION
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.Nm Disklabel
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installs, examines or modifes the label on a disk drive or pack. When writing
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the label, it can be used to change the drive identification, the disk
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partitions on the drive, or to replace a damaged label. There are several forms
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of the command that read (display), install or edit the label on a disk. In
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addition,
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.Nm
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can install bootstrap code.
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.Ss Raw or in-core label
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.Pp
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The disk label is resident close to or at the beginning of each disk partition.
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For faster access, the kernel maintains a copy in core at all times. By
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default, most
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.Nm
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access the in-core copy of the label. To access the raw (on-disk) copy, use the
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.Fl r
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option. This option allows a label to be installed on a disk without kernel
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support for a label, such as when labels are first installed on a system; it
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must be used when first installing a label on a disk. The specific effect of
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.Fl r
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is described under each command.
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.Pp
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.Ss Disk device name
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.Pp
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All
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.Nm
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forms require a disk device name, which should always be the raw
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device name representing the disk or slice. For example
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.Pa da0
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represents the entire disk irregardless of any DOS partitioning,
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and
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.Pa da0s1
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represents a slice. Some devices, most notably
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.Ar ccd ,
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require that the
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.Dq whole-disk
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(or
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.Dq c )
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partition be specified. For example
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.Pa ccd0c .
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You do not have to include the
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.Pa /dev/
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path prefix when specifying the device.
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.Nm
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will automatically prepend it.
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.Ss Reading the disk label
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.Pp
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To examine or save the label on a disk drive, use
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.Nm
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without options:
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.Pp
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.Nm
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.Op Fl r
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.Ar disk
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.Pp
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.Ar disk
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represents the raw disk in question, and may be in the form
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.Pa da0
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or
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.Pa /dev/da0c .
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It will display all of the parameters associated with the drive and its
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partition layout. Unless the
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.Fl r
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flag is given,
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the kernel's in-core copy of the label is displayed;
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if the disk has no label, or the partition types on the disk are incorrect,
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the kernel may have constructed or modified the label.
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If the
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.Fl r
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flag is given,
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.Nm
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reads the label from the raw disk and displays it. Both versions are usually
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identical except in the case where a label has not yet been initialized or
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is corrupt.
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.Ss Writing a standard label
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.Pp
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To write a standard label, use the form
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.Pp
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.Nm
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.Fl w
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.Op Fl r
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.Ar disk Ar disktype/auto
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.Oo Ar packid Oc
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.Pp
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.Nm
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.Fl w
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.Op Fl r
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.Ar disk
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auto
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.Pp
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The required arguments to
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.Nm
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are the drive to be labeled and the drive type as described in the
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.Pa disktab(5)
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file. The drive parameters and partitions are taken from that file. If
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different disks of the same physical type are to have different partitions, it
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will be necessary to have separate disktab entries describing each, or to edit
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the label after installation as described below. The optional argument is a
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pack identification string, up to 16 characters long. The pack id must be
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quoted if it contains blanks. If the
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.Fl r
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flag is given, the disk sectors containing the label and bootstrap
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will be written directly.
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A side-effect of this is that any existing bootstrap code will be overwritten
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and the disk rendered unbootable. See the boot options below for a method of
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writing the label and the bootstrap at the same time.
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If
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.Fl r
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is not specified,
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the existing label will be updated via the in-core copy and any bootstrap
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code will be unaffected.
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If the disk does not already have a label, the
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.Fl r
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flag must be used.
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In either case, the kernel's in-core label is replaced.
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.Pp
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For a virgin disk that is not known to
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.Xr disktab 5 ,
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.Ar disktype
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can be specified as
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.Dq auto .
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In this case, the driver is requested to produce a virgin label for the
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disk. This might or might not be successful, depending on whether the
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driver for the disk is able to get the required data without reading
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anything from the disk at all. It will likely succeed for all SCSI
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disks, most IDE disks, and vnode devices. Writing a label to the
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disk is the only supported operation, and the
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.Ar disk
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itself must be provided as the canonical name, i.e. not as a full
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path name.
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.Pp
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PC-based systems have special requirements in order for the BIOS to properly
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recognize a
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.Fx
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disklabel. Older systems may require what is known as a
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.Dq dangerously dedicated
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disklabel, which creates a fake DOS partition to work around problems older
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BIOSes have with modern disk geometries. On newer systems you generally want
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to create a normal DOS slice using
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.Ar fdisk
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and then create a
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.Fx
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disklabel within that slice. This is described
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later on in this page.
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.Pp
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Installing a new disklabel does not in of itself allow your system to boot
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a kernel using that label. You must also install boot blocks, which is
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described later on in this manual page.
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.Ss Editing an existing disk label
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.Pp
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To edit an existing disk label, use the form
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.Pp
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.Nm
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.Fl e
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.Op Fl r
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.Ar disk
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.Pp
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This command reads the label from the in-core kernel copy, or directly from the
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disk if the
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.Fl r
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flag is also specified. The label is written to a file in ASCII and then
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supplied to an editor for changes. If no editor is specified in an
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.Ev EDITOR
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environment variable,
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.Xr vi 1
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is used. When the editor terminates, the label file is used to rewrite the disk
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label. Existing bootstrap code is unchanged regardless of whether
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.Fl r
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was specified.
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.Ss Restoring a disk label from a file
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.Pp
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To restore a disk label from a file, use the form
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.Pp
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.Nm
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.Fl R
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.Op Fl r
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.Ar disk Ar protofile
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.Pp
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.Nm
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is capable of restoring a disk label that was previously saved in a file in ASCII format.
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The prototype file used to create the label should be in the same format as that
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produced when reading or editing a label. Comments are delimited by
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.Ar \&#
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and newline. As when writing a new label, any existing bootstrap code will be
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clobbered if
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.Fl r
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is specified and will be unaffected otherwise. See the boot options below for a
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method of restoring the label and writing the bootstrap at the same time.
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.Ss Enabling and disabling writing to the disk label area
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.Pp
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By default, it is not possible to write to the disk label area at the beginning
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of a disk. The disk driver silently ignores any attempt to do so. If you need
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to write to this area (for example, to obliterate the label), use the form
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.Pp
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.Nm
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.Op Fl W
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.Ar disk
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.Pp
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To disallow writing to the label area after previously allowing it, use the
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command
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.Pp
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.Nm
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.Op Fl N
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.Ar disk
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.Ss Installing bootstraps
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.Pp
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The final three forms of
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.Nm
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are used to install bootstrap code. If you are creating a
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.Dq dangerously-dedicated
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partition for compatibility with older PC systems,
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you generally want to specify the raw disk name such as
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.Pa da0.
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If you are creating a label within an existing DOS slice, you should specify
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the slice name such as
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.Pa da0s1 .
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Making a partition bootable can be tricky. If you are using a normal DOS
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slice you typically install (or leave) a standard MBR on the base disk and
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then install the
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.Fx
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bootblocks in the slice.
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.Pp
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.Nm
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.Fl B
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.Oo
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.Fl b Ar boot1
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.Fl s Ar boot2
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.Oc
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.Ar disk
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.Oo Ar disktype Oc
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.Pp
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This form installs the bootstrap only. It does not change the disk label.
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You should never use this command on a base disk unless you intend to create a
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.Dq dangerously-dedicated
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disk, such as
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.Ar da0 .
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This command is typically run on a slice such as
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.Ar da0s1 .
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.Pp
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.Nm
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.Fl w
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.Fl B
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.Oo
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.Fl b Ar boot1
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.Fl s Ar boot2
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.Oc
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.Ar disk Ar disktype
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.Oo Ar packid Oc
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.Pp
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This form corresponds to the
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.Dq write label
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command described above.
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In addition to writing a new volume label, it also installs the bootstrap.
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If run on a base disk this command will create a
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.Dq dangerously-dedicated
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label. This command is normally run on a slice rather then a base disk.
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.Pp
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.Nm
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.Fl R
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.Fl B
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.Oo
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.Fl b Ar boot1
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.Fl s Ar boot2
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.Oc
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.Ar disk Ar protofile
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.Oo Ar disktype Oc
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.Pp
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This form corresponds to the
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.Dq restore label
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command described above.
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In addition to restoring the volume label, it also installs the bootstrap.
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If run on a base disk this command will create a
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.Dq dangerously-dedicated
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label. This command is normally run on a slice rather then a base disk.
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.Pp
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The bootstrap commands always access the disk directly, so it is not necessary
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to specify the
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.Fl r
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flag.
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.Pp
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The bootstrap code is comprised of two boot programs. Specify the name of the
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boot programs to be installed in one of these ways:
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.Bl -enum
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.It
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Specify the names explicitly with the
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.Fl b
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and
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.Fl s
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flags.
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.Fl b
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indicates the primary boot program and
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.Fl s
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the secondary boot program. The boot programs are located in
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.Pa /boot .
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.It
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If the
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.Fl b
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and
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.Fl s
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flags are not specified, but
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.Ar disktype
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was specified, the names of the programs are taken from the
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.Dq b0
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and
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.Dq b1
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parameters of the
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.Xr disktab 5
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entry for the disk if the disktab entry exists and includes those parameters.
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.It
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Otherwise, the default boot image names are used:
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.Pa /boot/boot1
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and
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.Pa /boot/boot2
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for the standard stage1 and stage2 boot images (details may vary
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on architectures like the Alpha, where only a single-stage boot is used).
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.El
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.Ss Initializing/Formatting a bootable disk from scratch
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.Pp
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To initialize a disk from scratch the following sequence is recommended.
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Please note that this will wipe everything that was previously on the disk,
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including any
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.No non- Ns Fx
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slices.
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.Bl -enum
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.It
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Use
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.Ar fdisk
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to initialize the DOS partition table, creating a real whole-disk slice to
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hold the
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.Fx
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disklabel, and installing a master boot record.
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.It
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Use
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.Ar disklabel
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to initialize a virgin
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.Fx
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disklabel and install
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.Fx
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boot blocks.
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.It
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Use
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.Ar disklabel
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to edit your newly created label, addiing appropriate partitions.
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.It
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Finally newfs the filesystem partitions you created in the label. A typical
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disklabel partiioning scheme would be to have an
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.Dq a
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partition
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of approximately 128MB to hold the root filesystem, a
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.Dq b
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partition for
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swap, a
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.Dq d
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partition for /var (usually 128MB), an
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.Dq e
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partition
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for /var/tmp (usually 128MB), an
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.Dq f
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partition for /usr (usually around 2G),
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and finally a
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.Dq g
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partition for /home (usally all remaining space).
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Your mileage may vary.
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.El
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.Pp
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.Nm fdisk Fl BI Ar da0
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.Pp
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.Nm
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.Fl w
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.Fl r
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.Fl B
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.Ar da0s1
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auto
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.Pp
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.Pp
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.Nm
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.Fl e
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.Ar da0s1
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.Pp
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.Sh FILES
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.Bl -tag -width Pa -compact
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.It Pa /etc/disktab
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.It Pa /boot/
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.It Pa /boot/boot<n>
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.El
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.Sh SAVED FILE FORMAT
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.Nm
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uses an ASCII version of the label when examining, editing or restoring a disk
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label. The format is:
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.Bd -literal -offset 4n
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# /dev/da1c:
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type: SCSI
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disk: da0s1
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label:
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flags:
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bytes/sector: 512
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sectors/track: 51
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tracks/cylinder: 19
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sectors/cylinder: 969
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cylinders: 1211
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sectors/unit: 1173930
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rpm: 3600
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interleave: 1
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trackskew: 0
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cylinderskew: 0
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headswitch: 0 # milliseconds
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track-to-track seek: 0 # milliseconds
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drivedata: 0
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8 partitions:
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# size offset fstype [fsize bsize bps/cpg]
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a: 81920 0 4.2BSD 1024 8192 16 # (Cyl. 0 - 84*)
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b: 160000 81920 swap # (Cyl. 84* - 218*)
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c: 1173930 0 unused 0 0 # (Cyl. 0 - 1211*)
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h: 962010 211920 vinum # (Cyl. 218*- 1211*)
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.Ed
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.Pp
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Lines starting with a # mark are comments. Most of the other specifications are
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no longer used. The ones which must still be set correctly are:
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.Pp
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.Bl -hang -width 20n
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.It Nm label
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is an optional label, set by the
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.Ar packid
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option when writing a label.
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.It Nm flags
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Flags may be
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.Ar removable ,
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.Ar ecc
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or
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.Ar badsect .
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.Ar removable
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is set for removable media drives, but no current
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.Fx
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driver evaluates this
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flag.
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.Ar ecc
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is no longer supported;
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.Ar badsect
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specifies that the drive can perform bad sector remapping.
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.It Nm sectors/unit
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describes the total size of the disk. This value must be correct.
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.It Nm the partition table
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|
This is the UNIX partition table, not the Microsoft partition table described in
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.Xr fdisk 8 .
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|
.El
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|
.Pp
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|
The partition table can have up to 8 entries. It contains the following
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information:
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.Bl -hang -width 10n
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.It identifier
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|
The partition identifier is a single letter in the range
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.Nm a
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to
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.Nm h .
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|
By convention, partition
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.Nm c
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|
is reserved to describe the entire disk.
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.It size
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|
is the size of the partition in sectors.
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|
.It offset
|
|
is the offset of the start of the partition from the beginning of the drive.
|
|
.It fstype
|
|
describes the purpose of the partition. The example shows most normal usages.
|
|
For UFS file systems, use type 4.2BSD. See
|
|
.Pa /usr/include/sys/disklabel.h
|
|
for a complete list.
|
|
.It fsize
|
|
For file systems only, the fragment size.
|
|
.It bsize
|
|
For file systems only, the block size.
|
|
.It bps/cpg
|
|
For UFS file systems, the number of cylinders in a cylinder group. For LFS file
|
|
systems, the segment shift value.
|
|
.El
|
|
The remainder of the line is a comment and shows the cylinder allocations based
|
|
on the obsolete (but possibly correct) geometry information about the drive.
|
|
The asterisk (*) indicates that the partition does not begin or end exactly on a
|
|
cylinder boundary.
|
|
.Sh EXAMPLES
|
|
.Dl disklabel da0
|
|
.Pp
|
|
Display the in-core label for
|
|
.Pa da0s1
|
|
as obtained via
|
|
.Pa /dev/da0s1 .
|
|
When reading a label,
|
|
.Fx
|
|
will allow you to specify the base disk name
|
|
even if the label resides on a slice. However, to be proper you should
|
|
specify the base disk name only if you are using a
|
|
.Dq dangerously-dedicated
|
|
label. Normally you specify the slice.
|
|
.Pp
|
|
.Dl disklabel da0s1 > savedlabel
|
|
.Pp
|
|
Save the in-core label for
|
|
.Pa da0s1
|
|
into the file
|
|
.Pa savedlabel .
|
|
This file can be used with the
|
|
.Fl R
|
|
flag to restore the label at a later date.
|
|
.Pp
|
|
.Dl disklabel -w -r /dev/da0s1 da2212 foo
|
|
.Pp
|
|
Create a label for
|
|
.Pa da0s1
|
|
based on information for
|
|
.Dq da2212
|
|
found in
|
|
.Pa /etc/disktab .
|
|
Any existing bootstrap code will be clobbered.
|
|
.Pp
|
|
.Dl disklabel -e -r da0s1
|
|
.Pp
|
|
Read the on-disk label for
|
|
.Pa da0s1 ,
|
|
edit it and reinstall in-core as well as on-disk. Existing bootstrap code is
|
|
unaffected.
|
|
.Pp
|
|
.Dl disklabel -r -w da0s1 auto
|
|
.Pp
|
|
Try to auto-detect the required information from
|
|
.Pa da0s1 ,
|
|
and write a new label to the disk. Use another disklabel -e command to edit the
|
|
partitioning and file system information.
|
|
.Pp
|
|
.Dl disklabel -R da0s1 savedlabel
|
|
.Pp
|
|
Restore the on-disk and in-core label for
|
|
.Pa da0s1
|
|
from information in
|
|
.Pa savedlabel .
|
|
Existing bootstrap code is unaffected.
|
|
.Pp
|
|
.Dl disklabel -B da0s1
|
|
.Pp
|
|
Install a new bootstrap on
|
|
.Pa da0s1 .
|
|
The boot code comes from
|
|
.Pa /boot/boot1
|
|
and possibly
|
|
.Pa /boot/boot2 .
|
|
On-disk and in-core labels are unchanged.
|
|
.Pp
|
|
.Dl disklabel -w -B /dev/da0s1 -b newboot1 -s newboot da2212
|
|
.Pp
|
|
Install a new label and bootstrap.
|
|
The label is derived from disktab information for
|
|
.Dq da2212
|
|
and installed both in-core and on-disk.
|
|
The bootstrap code comes from the files
|
|
.Pa /boot/newboot1
|
|
and
|
|
.Pa /boot/newboot2 .
|
|
.Pp
|
|
.Dl dd if=/dev/zero of=/dev/da0 bs=512 count=32
|
|
.Dl fdisk -BI da0
|
|
.Dl dd if=/dev/zero of=/dev/da0s1 bs=512 count=32
|
|
.Dl disklabel -w -r -B da0s1 auto
|
|
.Dl disklabel -e da0s1
|
|
.Pp
|
|
Completely wipe any prior information on the disk, creating a new bootable
|
|
disk with a DOS partition table containing one
|
|
.Dq whole-disk
|
|
slice. Then
|
|
initialize the slice, then edit it to your needs. The
|
|
.Pa dd
|
|
commands are optional, but may be necessary for some BIOSes to properly
|
|
recognize the disk.
|
|
.Sh SEE ALSO
|
|
.Xr disklabel 5 ,
|
|
.Xr disktab 5 ,
|
|
.Xr boot0cfg 8 ,
|
|
.Xr fdisk 8
|
|
.Sh DIAGNOSTICS
|
|
The kernel device drivers will not allow the size of a disk partition
|
|
to be decreased or the offset of a partition to be changed while it is open.
|
|
Some device drivers create a label containing only a single large partition
|
|
if a disk is unlabeled; thus, the label must be written to the
|
|
.Dq a
|
|
partition of the disk while it is open. This sometimes requires the desired
|
|
label to be set in two steps, the first one creating at least one other
|
|
partition, and the second setting the label on the new partition while shrinking
|
|
the
|
|
.Dq a
|
|
partition.
|
|
.Pp
|
|
On some machines the bootstrap code may not fit entirely in the area
|
|
allocated for it by some filesystems.
|
|
As a result, it may not be possible to have filesystems on some partitions
|
|
of a
|
|
.Dq bootable
|
|
disk.
|
|
When installing bootstrap code,
|
|
.Nm
|
|
checks for these cases.
|
|
If the installed boot code would overlap a partition of type FS_UNUSED
|
|
it is marked as type FS_BOOT.
|
|
The
|
|
.Xr newfs 8
|
|
utility will disallow creation of filesystems on FS_BOOT partitions.
|
|
Conversely, if a partition has a type other than FS_UNUSED or FS_BOOT,
|
|
.Nm
|
|
will not install bootstrap code that overlaps it.
|
|
.Sh BUGS
|
|
When a disk name is given without a full pathname,
|
|
the constructed device name uses the
|
|
.Dq c
|
|
partition.
|
|
.Pp
|
|
For the i386 architecture, the primary bootstrap sector contains
|
|
an embedded
|
|
.Em fdisk
|
|
table.
|
|
.Nm Disklabel
|
|
takes care to not clobber it when installing a bootstrap only
|
|
.Pq Fl B ,
|
|
or when editing an existing label
|
|
.Pq Fl e ,
|
|
but it unconditionally writes the primary bootstrap program onto
|
|
the disk for
|
|
.Fl w
|
|
or
|
|
.Fl R ,
|
|
thus replacing the
|
|
.Em fdisk
|
|
table by the dummy one in the bootstrap program. This is only of
|
|
concern if the disk is fully dedicated, so that the BSD disklabel
|
|
starts at absolute block 0 on the disk.
|
|
.Pp
|
|
.Nm
|
|
does not perform adequate error checking. No warning is given if partitions
|
|
overlap, nor if space remains unused.
|