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disklabel(8)
NAME
disklabel - Reads and writes a disk pack label and formats disk partitions
SYNOPSIS
/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]
OPTIONS
-e Edits an existing label.
-f filename
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.
-F 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.
-n Writes an initial label to a disk which is then labeled, but not
bootable. Use the -wr option alone to create a bootable disk.
-N Disallows writing of the pack label area on the specified disk. (See
the -W option.)
-p Prints label operands for the specified disk to stdout.
-r 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.
-R Restores a disk label that was formatted in a prior operation and saved
in an ASCII file.
-s 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.
-t ufs|advfs|cdfs
Specifies which type of the local file system the boot blocks describe,
UFS, AdvFS, or CDFS.
-w Writes a standard label on the designated drive. Used with the -r
option, this option creates a bootable disk.
-W Allows writing of the pack label area on the specified disk. (See -N.)
-z Zeros (clears) the disk label.
PARAMETERS
disk
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.
filename
Specifies an image file name that the disklabel command reads to
perform the specified operation.
type
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"
SCSI-WWID: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.
packid
Specifies an optional pack identification string containing up to 16
characters. Use quotes (" ") around the packid parameter if it
contains space characters.
protofile
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.
xxboot
The primary bootstrap program which must be a valid boot file residing
in the /mdec directory.
bootxx
The secondary bootstrap program which must be a valid boot file
residing in the /mdec directory.
fstype
The file system type, which can be any of the options listed in the
following table:
File System Types
Usage Description
Value of fstype
unused Available for use
swap Swap space
UNIX file system
4.2BSD, ufs, or UFS
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
DESCRIPTION
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
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
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
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
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
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
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.
NOTES
· 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
EXAMPLES
1. 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]
2. 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
.
.
.
3. 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-to-track 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
4. 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
5. 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
6. 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
.
.
.
7. The following example marks partition dsk4c as unused, which means it
is available for use:
# disklabel -s dsk4c unused
8. 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
FILES
/dev/disk
Contains device special files, such as disk0a
/dev/rdisk
Contains raw device special files, such as disk1c
/etc/disktab
Contains information about disks and drives
/mdec/xxboot
Contains primary bootstrap programs
/mdec/bootxx
Contains secondary bootstrap programs
SEE ALSO
Commands: diskconfig(8), hwmgr(8)
Files: disklabel(4), disktab(4)
Misc: rz(7), ra(7)
Functions: check_usage(3), set_usage(3)
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