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disklabel (8)
  • >> disklabel (8) ( FreeBSD man: Команды системного администрирования )

  • BSD mandoc


     - read and write BSD label


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


    The utility installs, examines or modifies the BSD label on a disk partition, or on a file containing a partition image. In addition, 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 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 that the program will operate on a file instead of a disk partition.

    The -n option stops the program right before the disk would have been modified, and displays the result instead of writing it.

    The -m machine argument forces to use a layout suitable for a different architecture. Current valid values are i386 , amd64 , ia64 , pc98 and alpha If this option is omitted, will use a layout suitable for the current machine.  

    Reading the Disk Label

    To examine the label on a disk drive, use the form

    [-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

    -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, or if the type is specified as 'auto', a default layout is used.  

    Editing an Existing Disk Label

    To edit an existing disk label, use the form

    -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

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

    The utility is capable of restoring a disk label that was previously saved in a file in ASCII format. The prototype file used to create 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 option is specified, bootstrap code will be read from the file /boot/boot and written to the disk. The -b boot option allows a different file to be used.  


    Default boot image.
    Disk description file.



    The 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     2048 16384  5128
      b:  1091994    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
    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:

    file ...
    The partition identifier is a single letter in the range `a' to `h' By convention, partition `c' is reserved to describe the entire disk.
    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 partition `c' , a size of * indicates the entire disk. Lowercase versions of suffixes K , M and G are allowed. Size and suffix should be specified without any spaces between them.

    Example: 2097152, 1G, 1024M and 1048576K are all the same size (assuming 512-byte sectors).

    The offset of the start of the partition from the beginning of the drive in sectors, or * to have calculate the correct offset to use (the end of the previous partition plus one, ignoring partition `c' ) . For partition `c' , * will be interpreted as an offset of 0. The first partition should start at offset 16, because the first 16 sectors are reserved for metadata.
    Describes the purpose of the partition. The above example shows all currently used partition types. For UFS file systems and ccd(4) partitions, use type 4.2BSD For Vinum drives, use type vinum Other common types are swap and unused By convention, partition `c' represents the entire slice and should be of type unused though does not enforce this convention. The 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.)
    For 4.2BSD file systems only, the fragment size; see newfs(8).
    For 4.2BSD file systems only, the block size; see newfs(8).
    For 4.2BSD file systems, the number of cylinders in a cylinder group; see newfs(8).



    Display the label for the first slice of the da0 disk, as obtained via /dev/da0s1

    "bsdlabel da0s1"

    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 da0s1 > savedlabel"

    Create a label for da0s1

    "bsdlabel -w /dev/da0s1"

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

    "bsdlabel -e 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 -e -n da0s1"

    Write a default label on da0s1 Use another -e command to edit the partitioning and file system information:

    "bsdlabel -w da0s1"

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

    "bsdlabel -R da0s1 savedlabel"

    Display what the label would be for da0s1 using the partition 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 -R -n da0s1 label_layout"

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

    "bsdlabel -B da0s1"

    Install a new label and bootstrap. The bootstrap code comes from the file newboot in the current working directory:

    "bsdlabel -w -B -b newboot /dev/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 BIOS es to properly recognize the disk:

    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

    This is an example disk label that uses some of the new partition size types such as % , M , G and * which could be used as a source file for ``bsdlabel -R ad0s1 new_label_file ''

    # /dev/ad0s1:
    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


    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.  


    Due to the use of an Vt u_int32_t to store the number of sectors, 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 another method such as gpt(8).

    The various BSD s all use slightly different versions of BSD labels and are not generally compatible.  


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



    Disk Device Name
    General Options
    Reading the Disk Label
    Writing a Standard Label
    Editing an Existing Disk Label
    Restoring a Disk Label From a File
    Installing Bootstraps

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