bsdlabel(8)

NAME

bsdlabel - read and write disk pack label

SYNOPSIS

bsdlabel [-A] disk | -f file
bsdlabel -w [-An] [-B [-b boot]] [-m machine] disk | -f file
[type]
bsdlabel -e [-An] [-B [-b boot]] [-m machine] disk | -f file
bsdlabel -R [-An] [-B [-b boot]] [-m machine] [-f] disk | -f
file
         protofile

DESCRIPTION

The bsdlabel utility installs, examines or modifies the BSD

label on a
disk partition, or on a file containing a partition image.

In addition,
bsdlabel can install bootstrap code.

Disk Device Name

When specifying the device (i.e., when the -f option is not

used), the
/dev/ path prefix may be omitted; the bsdlabel utility will

automatically
prepend it.

General Options

The -A option enables processing of the historical parts of

the BSD
label. If the option is not given, suitable values are set

for these
fields.

The -f option tells bsdlabel that the program will operate

on a file
instead of a disk partition.

The -n option stops the bsdlabel program right before the

disk would have
been modified, and displays the result instead of writing

it.

The -m machine argument forces bsdlabel to use a layout

suitable for a
different architecture. Current valid values are i386,

amd64, ia64,
pc98, and alpha. If this option is omitted, bsdlabel will

use a layout
suitable for the current machine.

Reading the Disk Label

To examine the label on a disk drive, use bsdlabel without

options:

bsdlabel [-A] [-m machine] disk

disk represents the disk in question, and may be in the form

da0 or
/dev/da0. It will display the partition layout.

Writing a Standard Label

To write a standard label, use the form

bsdlabel -w [-An] [-m machine] disk [type]

If the drive type is specified, the entry of that name in

the disktab(5)
file is used; otherwise a default layout is used.

Editing an Existing Disk Label

To edit an existing disk label, use the form

bsdlabel -e [-An] [-m machine] disk

This command opens the disk label in the default editor, and

when the
editor exits, the label is validated and if OK written to

disk.

Restoring a Disk Label From a File

To restore a disk label from a file, use the form

bsdlabel -R [-An] [-m machine] disk protofile

bsdlabel is capable of restoring a disk label that was pre

viously saved
in a file in ASCII format. The prototype file used to cre

ate the label
should be in the same format as that produced when reading

or editing a
label. Comments are delimited by `#' and newline.

Installing Bootstraps

If the -B argument is specified, bootstrap code will be read

from the
file /boot/boot and written to the disk. The -b boot argu

ment allows a
different file to be used.

FILES

/boot/boot Default boot image.
/etc/disktab Disk description file.

SAVED FILE FORMAT

The bsdlabel utility uses an ASCII version of the label when

examining,
editing, or restoring a disk label. The format is:

8 partitions:
# size offset fstype [fsize bsize bps/cpg]

a: 81920 16 4.2BSD 1024 8192 16
b: 160000 81936 swap
c: 1173930 0 unused 0 0

# "raw" part, don't edit

If the -A option is specified, the format is:

# /dev/da1c:
type: SCSI
disk: da0s1
label:
flags:
bytes/sector: 512
sectors/track: 51
tracks/cylinder: 19
sectors/cylinder: 969
cylinders: 1211
sectors/unit: 1173930
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0 # milliseconds
track-to-track seek: 0 # milliseconds
drivedata: 0

8 partitions:
# size offset fstype [fsize bsize bps/cpg]

a: 81920 16 4.2BSD 1024 8192 16
b: 160000 81936 swap
c: 1173930 0 unused 0 0

# "raw" part, don't edit

Lines starting with a `#' mark are comments.

The partition table can have up to 8 entries. It contains

the following
information:

# The partition identifier is a single letter in the

range `a' to

`h'. By convention, partition `c' is reserved to

describe the
entire disk.

size The size of the partition in sectors, K (kilobytes

1024), M

(megabytes - 1024*1024), G (gigabytes

1024*1024*1024), % (percentage of free space after removing any fixed-size

partitions
other than partition `c'), or * (all remaining free

space after
fixed-size and percentage partitions). For parti

tion `c', a size
of * indicates the entire disk. Lowercase versions

of K, M, and
G are allowed. Size and type should be specified

without any
spaces between them.

Example: 2097152, 1G, 1024M and 1048576K are all the

same size
(assuming 512-byte sectors).

offset The offset of the start of the partition from the

beginning of

the drive in sectors, or * to have bsdlabel calcu

late the correct
offset to use (the end of the previous partition

plus one, ignoring partition `c'. For partition `c', * will be in

terpreted as
an offset of 0. The first partition should start at

offset 16,
because the first 16 sectors are reserved for meta

data.

fstype Describes the purpose of the partition. The example

shows all

currently used partition types. For UFS file sys

tems and ccd(4)
partitions, use type 4.2BSD. For Vinum drives, use

type vinum.
Other common types are swap and unused. By conven

tion, partition
`c' represents the entire slice and should be of

type unused,
though bsdlabel does not enforce this convention.

The bsdlabel
utility also knows about a number of other partition

types, none
of which are in current use. (See the definitions

starting with
FS_UNUSED in #include <sys/disklabel.h> for more details.)

fsize For 4.2BSD and LFS file systems only, the fragment

size.

Defaults to 1024 for partitions smaller than 1GB,

4096 for partitions 1GB or larger.

bsize For 4.2BSD and LFS file systems only, the block

size. Defaults

to 8192 for partitions smaller than 1GB, 16384 for

partitions 1GB
or larger.

bps/cpg

For 4.2BSD file systems, the number of cylinders in

a cylinder
group. For LFS file systems, the segment shift val

ue. Defaults
to 16 for partitions smaller than 1GB, 64 for parti

tions 1GB or
larger.

EXAMPLES

bsdlabel da0s1

Display the label for the first slice of the da0 disk, as

obtained via
/dev/da0s1.

bsdlabel da0s1 > savedlabel

Save the in-core label for da0s1 into the file savedlabel.

This file can
be used with the -R option to restore the label at a later

date.

bsdlabel -w /dev/da0s1

Create a label for da0s1.

bsdlabel -e da0s1

Read the label for da0s1, edit it, and install the result.

bsdlabel -e -n da0s1

Read the on-disk label for da0s1, edit it, and display what

the new label
would be (in sectors). It does not install the new label

either in-core
or on-disk.

bsdlabel -w da0s1

Write a default label on da0s1. Use another bsdlabel -e

command to edit
the partitioning and file system information.

bsdlabel -R da0s1 savedlabel

Restore the on-disk and in-core label for da0s1 from infor

mation in
savedlabel.

bsdlabel -R -n da0s1 label_layout

Display what the label would be for da0s1 using the parti

tion layout in
label_layout. This is useful for determining how much space

would be
allotted for various partitions with a labeling scheme using

%-based or *
partition sizes.

bsdlabel -B da0s1

Install a new bootstrap on da0s1. The boot code comes from

/boot/boot.

bsdlabel -w -B -b newboot /dev/da0s1

Install a new label and bootstrap. The bootstrap code comes

from the
file newboot in the current working directory.

dd if=/dev/zero of=/dev/da0 bs=512 count=32
fdisk -BI da0
dd if=/dev/zero of=/dev/da0s1 bs=512 count=32
bsdlabel -w -B da0s1
bsdlabel -e da0s1

Completely wipe any prior information on the disk, creating

a new
bootable disk with a DOS partition table containing one

slice, covering
the whole disk. Initialize the label on this slice, then

edit it. The
dd(1) commands are optional, but may be necessary for some

BIOSes to
properly recognize the disk.

This is an example disk label that uses some of the new par

tition size
types such as %, M, G, and *, which could be used as a

source file for
``bsdlabel -R ad0s1c new_label_file'':

# /dev/ad0s1c:

8 partitions:
# size offset fstype [fsize bsize bps/cpg]

a: 400M 16 4.2BSD 4096 16384 75

# (Cyl. 0 - 812*)
b: 1G * swap
c: * * unused
e: 204800 * 4.2BSD
f: 5g * 4.2BSD
g: * * 4.2BSD

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.

COMPATIBILITY

Due to the use of an u_int32_t to store the number of sec

tors, BSD labels
are restricted to a maximum of 2^32-1 sectors. This usually

means 2TB of
disk space. Larger disks should be partitioned using anoth

er method such
as gpt(8).

The various BSDs all use slightly different versions of BSD

labels and
are not generally compatible.

SEE ALSO

ccd(4), geom(4), md(4), disktab(5), boot0cfg(8), fdisk(8),

gpt(8)

BSD March 15, 2003

BSD