disklabel - Reads and writes a disk pack label and formats
disk partitions
/sbin/disklabel [-r] [disk]
/sbin/disklabel [-r] -f filename
/sbin/disklabel -w disk [type[packid]]
/sbin/disklabel -wr [-n] [-t {ufs | advfs}] [disk] [type
[packid] [xxboot bootxx]]
/sbin/disklabel -wr [-n] [-t {ufs | advfs | cdfs}]
-ffilename [packid] [xxboot bootxx]
/sbin/disklabel -e [-r] disk
/sbin/disklabel -e -f filename
/sbin/disklabel -R [-t {ufs | advfs}] disk protofile
/sbin/disklabel -Rr [-t {ufs | advfs}] disk protofile {
type | xxboot bootxx }
/sbin/disklabel [-N | -W] disk
/sbin/disklabel -z disk
/sbin/disklabel -s -F disk fstype
/sbin/disklabel -p disk [type]
Edits an existing label. Specifies the type of image file
for operations. The default image file type is cdfs, to
indicate that the image file was created in ISO 9660 Rock
Ridge format. The cdfs default applies only when the -f
option is used. Enables you to force an override of the
current file system type. You can set the file system type
by using the -s option. If the target disk partition is in
use, the disklabel command displays a warning message and
does not set a file system type. This safety feature prevents
you from accidentally overwriting any partition that
is in use. If you are certain that you want to set a new
file system type, you can choose to ignore the warning and
specify the -F option to override the safety feature.
Writes an initial label to a disk which is then labeled,
but not bootable. Use the -wr option alone to create a
bootable disk. Disallows writing of the pack label area
on the specified disk. (See the -W option.) Prints label
operands for the specified disk to stdout. Reads or
writes the label directly to or from the disk, rather than
operating on the in-memory copy of the label. Used with
the -w option, this option creates a bootable disk.
Restores a disk label that was formatted in a prior operation
and saved in an ASCII file. Sets the file system
type (fstype) field in the disk label. See the -F option,
which enables you to force an override of any existing
settings. Specifies which type of the local file system
the boot blocks describe, UFS, AdvFS, or CDFS. Writes a
standard label on the designated drive. Used with the -r
option, this option creates a bootable disk. Allows writing
of the pack label area on the specified disk. (See
-N.) Zeros (clears) the disk label.
Identifies the disk on which you want to perform a
labelling operation. You use the disk's device special
file name, such as dsk0 or /dev/rdisk/dsk0a. If you do
not specify the disk partition, the disklabel command uses
the first partition that has a zero offset. Typically,
this is the a or c partition. If the full path name is
used, it must be a character special device name and not
the block device name. Specifies an image file name that
the disklabel command reads to perform the specified operation.
Specifies the type (or model) of disk. This
parameter is optional. The /etc/disktab file contains a
list of disk types and their operands and partitions. If
you want disks that are the same type to have different
partition operands, create separate /etc/disktab file
entries describing each disk, or edit the disks' labels
after installation with the -e option. See disktab(4) for
more information. If your disk type is not specified in
the /etc/disktab file, the disklabel command uses the
default partition information in the driver. You can also
use the following command to display disk types:
# hwmgr -show comp | grep WWID
COMPONENT NAME SCSI-WWID:0410003a:"DEC RZ26L (C)
DECPCB=ZG51569480 ; HDA=000051892202" SCSIWWID:04100024:"COMPAQ
HB00931B93 WT7050055125"
SCSI-WWID:0c000008:0060-9487-2a12-4ed2
The preceding output is edited to show only the
COMPONENT NAME column. The disk type is contained
in the quoted string of the worldwide identifier
(WWID), which is the manufacturer's model information.
This data appears under the COMPONENT NAME
column. The first field contains the manufacturer's
code, such as COMPAQ The second field contains the
disk type, such as RZ26L or HB00931B93. The example
device shown on the last line of the output contains
no information on the disk type. In such
cases, you cannot specify a type, and the disklabel
command uses the default partition information in
the device driver.
See hwmgr(8) for more information. Specifies an
optional pack identification string containing up
to 16 characters. Use quotes (" ") around the
packid parameter if it contains space characters.
Specifies a prototype file that is used to create
the label. This file is in the same format as the
output produced when you read or edit a label. You
can add comments by preceding the comment string
with a pound sign (#) and ending it by using the
newline character. The primary bootstrap program
which must be a valid boot file residing in the
/mdec directory. The secondary bootstrap program
which must be a valid boot file residing in the
/mdec directory. The file system type, which can
be any of the options listed in the following
table:
File System Types
Value of fstype Usage Description
unused Available for use
swap Swap space
4.2BSD, ufs, or UFS UNIX file system
AdvFS AdvFS file system. This string is case sensistive.
You cannot use advfs.
cdfs CDFS file system
LSMnoprv An LSM nopriv disk
LSMpriv An LSM private region
LSMpubl An LSM public region
LSMsimp An LSM simple disk
database A database
raw Raw data
Use the disklabel command to install, examine, or modify
the label on a disk drive or pack. The disk label contains
information about the disk, such as its type and physical
operands. See rz(7) for information on SCSI disk partitions.
The diskconfig graphical user interface (GUI) provides
an alternate way to label and partition disks. If
you need to create custom partition sizes on a disk, the
diskconfig command provides you with the easiest method.
See diskconfig(8) for more information.
You also use the disklabel command to do the following
tasks: Change the drive identification Modify the size and
usage of disk partitions on the drive Replace a damaged
label Change the bootstrap program
These tasks are referred to as formatting operations on
other operating systems.
The disk label is located on one of the first sectors of
each disk, which is usually block 0 (zero). On systems
that require a block-zero bootstrap, the label is inserted
into the bootstrap program. There are two copies of a disk
label, one located on the disk and one located in system
memory. Because it is faster to access system memory than
to perform I/O, when a system recognizes a disk, it copies
the disk label into memory.
Reading and Writing a Label [Toc] [Back]
Use the -r option to read the label from or write it to
the disk directly, instead of reading the system's in-memory
copy of the label. When writing a label, the in-memory
copy is also updated provided the label operands are
valid. You must use the -r option if a disk has no label.
This option might enable you to install a label on a disk
that does not have kernel support for a label, such as
when labels are first installed on a system. You also use
the -r option to examine the label on the specified disk
drive. The disklabel command displays all of the operands
associated with the drive and its partition layout. If
the disk has no label or if the partition types on the
disk are incorrect, the kernel might have constructed or
modified the label.
Use the -w option to write a standard label on the designated
drive. You must specify the disk name. The type and
packid arguments are optional. If you specify the -r
option with the -w option, the disk sectors that contain
the label and bootstrap are written directly; otherwise
the existing label is updated in place without modifying
the bootstrap. In either case, the kernel's in-memory
label is replaced. You can specify alternate versions of
the bootstrap files, using the xxboot and bootxx arguments.
If an alternate bootstrap is not specified, the
standard bootstrap is used. See Specifying Bootstrap Programs
for more information.
The -wr options create a bootable disk by default and you
must specify the -n option to create a non bootable disk
label. When using the -n option, you can choose to specify
the disk, the type, and the packid depending on how you
want the disk labeled.
The -N option disables writing to the disk pack label
area. The -W option enables writing to the disk pack label
area. The label sector is always write-protected when the
drive is first opened; the write-enable option set by -W
persists only until all partitions on the drive are
closed.
Specifying Bootstrap Programs [Toc] [Back]
If you specify the -ffilename option with the -w option,
the disk label is written to the specified image file.
The default bootstrap programs are for the CDFS file system.
You can use alternative bootstrap programs by specifying
the -t option and indicating the file system type,
such as ufs. Alternatively, you can specify primary and
secondary (xxboot and bootxx) boot arguments.
The bootstrap programs are located in the /mdec directory.
You can specify the file names of the bootstrap programs
in the /etc/disktab file. If you do not specify the names,
the syntax of the default file names is as follows: xxboot
- The primary bootstrap, loaded at block 0 (zero). bootxx
- The secondary bootstrap, loaded as follows: Blocks 1-15
for the UFS file system Blocks 64-95 for the AdvFS file
system
The replaceable string, xx, specifies the type of disk,
such as, rz or re. For example, the names are /mdec/rzboot
and /mdec/bootrz for a UFS type rz disk.
Note
In Version 5.0 and later the rz device naming convention
for SCSI disks changed to a dsk device naming convention.
However, rz basenames still apply to SCSI disks. The
/mdec/*rz* files map to any dsk device. See System Administration
for information on device naming. See hwmgr(8)
for information on finding devices and device names.
For example, If you specify the -t advfs option when
labeling dsk1, the disklabel command uses the
/mdec/rzboot.advfs and /mdec/bootrz.advfs files by
default.
Printing a Label [Toc] [Back]
Use the -p option to print the disklabel operands for a
specified disk from the /etc/disktab file to stdout. The
type of disk is obtained directly by querying the disk
special file. If there is no matching entry in the
/etc/disktab file for the obtained type, the disklabel
command uses the default partition information in the
driver.
If the optional type parameter is specified, it takes
precedence over the disk special file, and the information
is obtained from /etc/disktab providing a matching entry
is found for the specified type. If no matching entry is
found, the disklabel command uses the default partition
information from the device driver.
Editing a Label [Toc] [Back]
You can edit an existing disk label by using the -e
option. The label is read from the in-memory kernel copy,
or directly from the disk if you specify the -r option.
The label is formatted and then sent to an editor. If no
editor is specified with the EDITOR environment variable,
the vi editor is used. If vi is not available, the ed
editor is used.
If an unexpected error occurs during the ed editing session,
the following message is displayed: Warning, edit
session exited abnormally!
You MUST re-edit the disk label to ensure that the modifications
you made were saved correctly.
When the editor terminates, the formatted label is reread
and is used by the disklabel command to rewrite the disk
label.
Restoring a Label [Toc] [Back]
If you specify the -R option, the disklabel command
restores a disk label that was previously formatted and
saved in an ASCII file. You can also specify a prototype
file that is used to resotre the label. If you also specify
the -r option, a block-0 bootstrap is installed on
systems that use that type of bootstrap. You must specify
either the disk type or the names of the bootstrap files
when labelling a disk for use on such systems. See the
Owner's manual for your system for more information.
If you replace an existing label with a new label, the
existing partition information will be copied to the new
label if the new label's partition is marked unused. This
might cause disklabel to fail and you can avoid this failure
by using the -z option to first clear the disk label
before performing the restoration operation.
Changing the File System Type [Toc] [Back]
Use the -s option to change the file system type (fstype)
in the disk label. Specify the disk partition, such as
dsk10c, and the new value for the fstype parameter, such
as ufs.
If a partition no longer contains valid file system data,
use the -s option to set the fstype parameter to unused.
Or, if the fstype parameter is unused, but the partition
does contain valid data, use the -s option to set a valid
value for the fstype parameter. This prevents inadvertent
loss of data, as applications such as newfs, mkfdmn, voldisk,
and swapon check the fstype field in the disk label
for the partition usage.
If a partition is already in use, the diskabel command
might display a warning message and the partition file
system type does not changed. You can force an override of
this safety feature by using the -F option with the -s
option.
The kernel device drivers do not allow the size of a disk
partition to be decreased or the offset of a partition to
be changed while the partition 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 a or c partition of the disk while it is
open. This sometimes requires that the desired label be
set in two steps, the first one creating at least one
other partition, and the second one setting the label on
the new partition while shrinking the a partition.
The kernel does not allow file system information
to be set unused for open partitions. For example,
if you want to set the a partition to unused, you
must write the label using a different partition
(such as the c partition). For example:
# disklabel -w /dev/rdisk/dsk0c
If a file system exists for an open partition, the
existing file system information is copied to the
new label. This preserves the existing information
without returning an error. When using LSM, if you
try to recover a replaced mirror disk and the disk
has been replaced with a new disk, the disklabel
command fails with the following error, when
attempting to write the new label:
disklabel: ioctl DIOCSDINFO: open partition would
move or shrink
Remove the disk from LSM before attempting to write
the new label:
# voldisk rm dsk8 # disklabel -wr dsk8
If you enter the disklabel command but do not specify any
options, the following command usage help is displayed:
# disklabel Usage:
Read 'in-memory copy' of label:
disklabel disk
Read 'on-disk copy' of label:
disklabel -r disk
Read label from image file:
disklabel [-r] -f filename
Write over existing label:
disklabel -w disk [type [packid]]
Write initial label on disk:
disklabel -wr [-n] [-t {advfs | ufs}] disk
[type [packid]
[xxboot bootxx]]
Write label to image file:
disklabel -wr [-n] [-t {advfs | ufs | cdfs}]
-f filename
[packid] [xxboot bootxx]
Edit label:
disklabel -e [-r] disk
Edit label on image file:
disklabel -e -f filename
Restore label:
disklabel -R [-t {advfs | ufs}] disk
protofile
disklabel -Rr [-t {advfs | ufs}] disk
protofile
[type | xxboot bootxx]
Write disable/enable label:
disklabel [-N | -W] disk
Zero label:
disklabel -z disk
Set partition fstype:
disklabel -s [-F] disk fstype
Print Default label:
disklabel -p disk [type] The following example
indicates which variants of the device special file
name are acceptable. The disk is labeled with partitions
a, b, and g:
# disklabel /dev/disk/dsk1 disklabel:
/dev/disk/dsk1: No such file or directory # disklabel
/dev/disk/dsk1c
disklabel: not a character device:
/dev/disk/dsk1c # disklabel /dev/disk/dsk1a
disklabel: not a character device:
/dev/disk/dsk1a # disklabel /dev/rdisk/dsk1 disklabel:
/dev/rdisk/dsk1: No such file or directory #
disklabel /dev/rdisk/dsk1c # /dev/rdisk/dsk1c:
type: SCSI disk: RZ28M label: . . . # disklabel
dsk1 # /dev/rdisk/dsk1c: type: SCSI disk: RZ28M
label: flags: . . .
# disklabel dsk1g # /dev/rdisk/dsk1g: type: SCSI
disk: RZ28M label: . . . # disklabel
/dev/rdisk/dsk1g # /dev/rdisk/dsk1g: type: SCSI
disk: RZ28M label: flags: . . . # disklabel
/dev/disk/dsk1g
disklabel: not a character device:
/dev/disk/dsk1g . . . The following example uses
only the -r (read) option to read and display the
on-disk copy of the disk label:
# disklabel -r dsk1 # /dev/rdisk/dsk1c: type: SCSI
disk: RZ28M label: flags: bytes/sector: 512 sectors/track:
99 tracks/cylinder: 16 sectors/cylinder:
1584 cylinders: 2595 sectors/unit: 4110480
rpm: 3600 interleave: 1 trackskew: 0 cylinderskew:
0 headswitch: 0 # milliseconds track-totrack
seek: 0 # milliseconds drivedata: 0
8 partitions: # size offset
fstype fsize bsize cpg # ~Cyl values
a: 262144 0 4.2BSD 1024
8192 16 # 0 - 165*
b: 401404 262144 swap
# 165*- 418*
c: 4110480 0 unused 1024
8192 # 0 - 2594
d: 1060869 663547 unused 1024
8192 # 418*- 1088*
e: 1191936 1724416 unused 1024
8192 # 1088*- 1841*
f: 1194128 2916352 unused 1024
8192 # 1841*- 2594
g: 3446932 663548 4.2BSD 1024
8192 16 # 418*- 2594
h: 1790096 2320384 unused 1024
8192 # 1464*- 2594
The following command indicates an error caused by
attempting a labeling operation on a disk that is
in use. In this case, a partition on the disk was
still mounted when the command was issued:
# disklabel -rw dsk1
disklabel: ioctl DIOCSDINFO: Open partition would
move or shrink
Use alternate partition
The following example clears the existing label,
writes a new label, and then displays the current
label. This disk is the same disk used in Example
3, and you can compare the differences in the
label:
# disklabel -rw dsk1 # disklabel -r dsk1 #
/dev/rdisk/dsk1c: type: SCSI disk: RZ28M label:
flags: bytes/sector: 512 sectors/track: 99
tracks/cylinder: 16 sectors/cylinder: 1584 cylinders:
2595 sectors/unit: 4110480 rpm: 5411 interleave:
1 trackskew: 12 cylinderskew: 25 headswitch:
0 # milliseconds track-to-track seek: 0
# milliseconds drivedata: 0
8 partitions: # size offset
fstype fsize bsize cpg # ~Cyl values
a: 131072 0 unused 0
0 # 0 - 82*
b: 401408 131072 unused 0
0 # 82*- 336*
c: 4110480 0 unused 0
0 # 0 - 2594
d: 1191936 532480 unused 0
0 # 336*- 1088*
e: 1191936 1724416 unused 0
0 # 1088*- 1841*
f: 1194128 2916352 unused 0
0 # 1841*- 2594
g: 1787904 532480 unused 0
0 # 336*- 1464*
h: 1790096 2320384 unused 0
0 # 1464*- 2594 The following example
marks partition dsk1c for use by the UFS file system
(4.2BSD). The second command issued attempts to
change the usage to swap space but instead returns
an error message stating that the partition is in
use. This safety feature prevents you from losing
data by accidentally overwriting in-use partitions:
# disklabel -s dsk1 ufs # disklabel -s dsk1 swap
disklabel: /dev/rdisk/dsk1c is marked in use for
4.2BSD by the disklabel.
disklabel: Use -F option to force an override.
The following command overrides the safety feature
and the output shows than usage of partition dsk1c
is changed:
# disklabel -s -F dsk1 swap # disklabel -r dsk1 #
/dev/rdisk/dsk1c: type: SCSI disk: RZ28M . . . #
size offset fstype fsize bsize cpg #
~Cyl values
c: 4110480 0 swap
# 0 - 2594 . . . The following example
marks partition dsk4c as unused, which means it is
available for use:
# disklabel -s dsk4c unused The following example
shows how a disk label is written to a CDFS image
file and then read from it:
# disklabel -r dsk1 > system.image # disklabel -w
-f system.image # disklabel -f system.image # system.image:
type: unknown disk: CDROM label: flags:
removeable bytes/sector: 512 sectors/track: 2
tracks/cylinder: 1 sectors/cylinder: 1 cylinders: 1
sectors/unit: 2 rpm: 300 interleave: 1 trackskew: 0
cylinderskew: 0 headswitch: 0 # milliseconds
track-to-track seek: 0 # milliseconds drivedata:
0
3 partitions: # size offset
fstype fsize bsize cpg # ~Cyl values
a: 2 0 CDFS
# 0 - 1
b: 0 0 unused 0
0 # 0 - 0
Contains device special files, such as disk0a Contains raw
device special files, such as disk1c Contains information
about disks and drives Contains primary bootstrap programs
Contains secondary bootstrap programs
Commands: diskconfig(8), hwmgr(8)
Files: disklabel(4), disktab(4)
Misc: rz(7), ra(7)
Functions: check_usage(3), set_usage(3)
disklabel(8)
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