1 .\" Copyright (c) 1987, 1988, 1991, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" This code is derived from software contributed to Berkeley by
5 .\" Symmetric Computer Systems.
7 .\" Redistribution and use in source and binary forms, with or without
8 .\" modification, are permitted provided that the following conditions
10 .\" 1. Redistributions of source code must retain the above copyright
11 .\" notice, this list of conditions and the following disclaimer.
12 .\" 2. Redistributions in binary form must reproduce the above copyright
13 .\" notice, this list of conditions and the following disclaimer in the
14 .\" documentation and/or other materials provided with the distribution.
15 .\" 3. All advertising materials mentioning features or use of this software
16 .\" must display the following acknowledgment:
17 .\" This product includes software developed by the University of
18 .\" California, Berkeley and its contributors.
19 .\" 4. Neither the name of the University nor the names of its contributors
20 .\" may be used to endorse or promote products derived from this software
21 .\" without specific prior written permission.
23 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 .\" @(#)disklabel.8 8.2 (Berkeley) 4/19/94
36 .\" $FreeBSD: src/sbin/disklabel/disklabel.8,v 1.15.2.22 2003/04/17 17:56:34 trhodes Exp $
37 .\" $DragonFly: src/sbin/disklabel64/disklabel64.8,v 1.4 2008/05/02 02:05:05 swildner Exp $
44 .Nd read and write disk pack label
53 .Ar disk Ar disktype/auto
76 .Oo Ar disktype/auto Oc
85 .Ar disk Ar disktype/auto
96 .Oo Ar disktype/auto Oc
98 .Fl f Ar slice_start_lba
104 installs, examines or modifies the label on a disk drive or pack.
106 the label, it can be used to change the drive identification, the disk
107 partitions on the drive, or to replace a damaged label.
108 There are several forms
109 of the command that read (display), install or edit the label on a disk.
113 can install bootstrap code.
114 .Ss Raw or in-core label
115 The disk label resides close to or at the beginning of each disk slice.
116 For faster access, the kernel maintains a copy in core at all times.
118 default, most forms of the
120 command access the in-core copy of the label.
121 To access the raw (on-disk)
125 This option allows a label to be installed on a disk without kernel
126 support for a label, such as when labels are first installed on a system; it
127 must be used when first installing a label on a disk.
128 The specific effect of
130 is described under each command.
134 forms require a disk device name, which should always be the raw
135 device name representing the disk or slice.
138 represents the entire disk regardless of any DOS partitioning,
142 Some devices, most notably
148 partition be specified.
151 You do not have to include the
153 path prefix when specifying the device.
156 utility will automatically prepend it.
157 .Ss Reading the disk label
158 To examine the label on a disk drive, use
167 represents the raw disk in question, and may be in the form
171 It will display all of the parameters associated with the drive and its
176 the kernel's in-core copy of the label is displayed;
177 if the disk has no label, or the partition types on the disk are incorrect,
178 the kernel may have constructed or modified the label.
183 reads the label from the raw disk and displays it.
184 Both versions are usually
185 identical except in the case where a label has not yet been initialized or
187 .Ss Writing a standard label
188 To write a standard label, use the form
194 .Ar disk Ar disktype/auto
204 The required arguments to
206 are the drive to be labeled and the drive type as described in the
209 The drive parameters and partitions are taken from that file.
211 different disks of the same physical type are to have different partitions, it
212 will be necessary to have separate disktab entries describing each, or to edit
213 the label after installation as described below.
214 The optional argument is a
215 pack identification string, up to 16 characters long.
217 quoted if it contains blanks.
221 flag is given, no data will be written to the device, and instead the
222 disklabel that would have been written will be printed to stdout.
226 flag is given, the disk sectors containing the label and bootstrap
227 will be written directly.
228 A side-effect of this is that any existing bootstrap code will be overwritten
229 and the disk rendered unbootable.
230 See the boot options below for a method of
231 writing the label and the bootstrap at the same time.
235 the existing label will be updated via the in-core copy and any bootstrap
236 code will be unaffected.
237 If the disk does not already have a label, the
240 In either case, the kernel's in-core label is replaced.
242 For a virgin disk that is not known to
247 In this case, the driver is requested to produce a virgin label for the
249 This might or might not be successful, depending on whether the
250 driver for the disk is able to get the required data without reading
251 anything from the disk at all.
252 It will likely succeed for all SCSI
253 disks, most IDE disks, and vnode devices.
254 Writing a label to the
255 disk is the only supported operation, and the
257 itself must be provided as the canonical name, i.e.\& not as a full
260 For most harddisks, a label based on percentages for most partitions (and
261 one partition with a size of
263 will produce a reasonable configuration.
265 PC-based systems have special requirements in order for the BIOS to properly
269 Older systems may require what is known as a
270 .Dq dangerously dedicated
271 disklabel, which creates a fake DOS partition to work around problems older
272 BIOSes have with modern disk geometries.
273 On newer systems you generally want
274 to create a normal DOS partition using
278 disklabel within that slice.
280 later on in this page.
282 Installing a new disklabel does not in of itself allow your system to boot
283 a kernel using that label.
284 You must also install boot blocks, which is
285 described later on in this manual page.
286 .Ss Editing an existing disk label
287 To edit an existing disk label, use the form
295 This command reads the label from the in-core kernel copy, or directly from the
298 flag is also specified.
299 The label is written to a file in ASCII and then
300 supplied to an editor for changes.
301 If no editor is specified in an
303 environment variable,
306 When the editor terminates, the label file is used to rewrite the disk
308 Existing bootstrap code is unchanged regardless of whether
313 is specified, no data will be written to the device, and instead the
314 disklabel that would have been written will be printed to stdout.
316 useful to see how a partitioning scheme will work out for a specific disk.
317 .Ss Restoring a disk label from a file
318 To restore a disk label from a file, use the form
324 .Ar disk Ar protofile
327 is capable of restoring a disk label that was previously saved in a file in ASCII format.
328 The prototype file used to create the label should be in the same format as that
329 produced when reading or editing a label.
330 Comments are delimited by
333 As when writing a new label, any existing bootstrap code will be
336 is specified and will be unaffected otherwise.
337 See the boot options below for a
338 method of restoring the label and writing the bootstrap at the same time.
341 is used, no data will be written to the device, and instead the
342 disklabel that would have been written will be printed to stdout.
344 useful to see how a partitioning scheme will work out for a specific disk.
345 .Ss Enabling and disabling writing to the disk label area
346 By default, it is not possible to write to the disk label area at the beginning
348 The disk driver arranges for
350 and similar system calls
353 on any attempt to do so.
355 to write to this area (for example, to obliterate the label), use the form
361 To disallow writing to the label area after previously allowing it, use the
367 .Ss Installing bootstraps
368 The final three forms of
370 are used to install bootstrap code.
371 If you are creating a
372 .Dq dangerously-dedicated
373 slice for compatibility with older PC systems,
374 you generally want to specify the raw disk name such as
376 If you are creating a label within an existing DOS slice,
378 the partition name such as
380 Making a slice bootable can be tricky.
381 If you are using a normal DOS
382 slice you typically install (or leave) a standard MBR on the base disk and
385 bootblocks in the slice.
396 This form installs the bootstrap only.
397 It does not change the disk label.
398 You should never use this command on a base disk unless you intend to create a
399 .Dq dangerously-dedicated
402 This command is typically run on a slice such as
416 This form corresponds to the
418 command described above.
419 In addition to writing a new volume label, it also installs the bootstrap.
420 If run on a base disk this command will create a
421 .Dq dangerously-dedicated
423 This command is normally run on a slice rather than a base disk.
426 is used, no data will be written to the device, and instead the
427 disklabel that would have been written will be printed to stdout.
437 .Ar disk Ar protofile
440 This form corresponds to the
442 command described above.
443 In addition to restoring the volume label, it also installs the bootstrap.
444 If run on a base disk this command will create a
445 .Dq dangerously-dedicated
447 This command is normally run on a slice rather than a base disk.
449 The bootstrap commands always access the disk directly, so it is not necessary
455 is used, no data will be written to the device, and instead the
456 disklabel that would have been written will be printed to stdout.
458 The bootstrap code is comprised of two boot programs.
459 Specify the name of the
460 boot programs to be installed in one of these ways:
463 Specify the names explicitly with the
469 indicates the primary boot program and
471 the secondary boot program.
472 The boot programs are located in
479 flags are not specified, but
481 was specified, the names of the programs are taken from the
487 entry for the disk if the disktab entry exists and includes those parameters.
489 Otherwise, the default boot image names are used:
493 for the standard stage1 and stage2 boot images.
495 .Ss Initializing/Formatting a bootable disk from scratch
496 To initialize a disk from scratch the following sequence is recommended.
497 Please note that this will wipe everything that was previously on the disk,
505 to initialize the hard disk, and create a slice table, referred to
507 .Dq "partition table"
513 to define partitions on
515 slices created in the previous step.
519 to create file systems on new partitions.
522 A typical partitioning scheme would be to have an
525 of approximately 128MB to hold the root file system, a
541 (usually around 2GB),
546 (usually all remaining space).
547 Your mileage may vary.
549 .Nm fdisk Fl BI Pa da0
560 .Bl -tag -width ".Pa /etc/disktab" -compact
564 Disk description file.
566 .Sh SAVED FILE FORMAT
572 version of the label when examining, editing, or restoring a disk
575 .Bd -literal -offset 4n
584 sectors/cylinder: 969
586 sectors/unit: 1173930
591 headswitch: 0 # milliseconds
592 track-to-track seek: 0 # milliseconds
600 h: 962010 211920 vinum
603 Lines starting with a
606 Most of the other specifications are no longer used.
607 The ones which must still be set correctly are:
610 is an optional label, set by the
612 option when writing a label.
619 is set for removable media drives, but no current
621 driver evaluates this
624 is no longer supported;
626 specifies that the drive can perform bad sector remapping.
628 describes the total size of the disk.
629 This value must be correct.
630 .It Ar "the partition table"
633 partition table, not the
635 partition table described in
639 The partition table can have up to 16 entries.
640 It contains the following information:
641 .Bl -tag -width indent
643 The partition identifier is a single letter in the range
647 By convention, partition
649 is reserved to describe the entire disk.
651 The size of the partition in sectors,
655 (megabytes - 1024*1024),
657 (gigabytes - 1024*1024*1024),
659 (percentage of free space
661 removing any fixed-size partitions other than partition
665 (all remaining free space
667 fixed-size and percentage partitions).
672 indicates the entire disk.
673 Lowercase versions of
678 Size and type should be specified without any spaces between them.
680 Example: 2097152, 1G, 1024M and 1048576K are all the same size
681 (assuming 512-byte sectors).
683 The offset of the start of the partition from the beginning of the
688 calculate the correct offset to use (the end of the previous partition plus
689 one, ignoring partition
694 will be interpreted as an offset of 0.
696 Describes the purpose of the partition.
697 The example shows all currently used partition types.
704 For Vinum drives, use type
706 Other common types are
710 By convention, partition
712 represents the entire slice and should be of type
716 does not enforce this convention.
720 also knows about a number of other partition types,
721 none of which are in current use.
722 (See the definitions starting with
725 .In sys/disklabel64.h
729 .Dl "disklabel64 da0s1"
731 Display the in-core label for the first slice of the
733 disk, as obtained via
736 .Dq dangerously-dedicated ,
737 the base disk name should be specified, such as
740 .Dl "disklabel64 da0s1 > savedlabel"
742 Save the in-core label for
746 This file can be used with the
748 option to restore the label at a later date.
750 .Dl "disklabel64 -w -r /dev/da0s1 da2212 foo"
754 based on information for
758 Any existing bootstrap code will be clobbered
759 and the disk rendered unbootable.
761 .Dl "disklabel64 -e -r da0s1"
763 Read the on-disk label for
765 edit it, and reinstall in-core as well as on-disk.
766 Existing bootstrap code is unaffected.
768 .Dl "disklabel64 -e -r -n da0s1"
770 Read the on-disk label for
772 edit it, and display what the new label would be (in sectors).
775 install the new label either in-core or on-disk.
777 .Dl "disklabel64 -r -w da0s1 auto"
779 Try to auto-detect the required information from
781 and write a new label to the disk.
785 partitioning and file system information.
787 .Dl "disklabel64 -R da0s1 savedlabel"
789 Restore the on-disk and in-core label for
793 Existing bootstrap code is unaffected.
795 .Dl "disklabel64 -R -n da0s1 label_layout"
797 Display what the label would be for
799 using the partition layout in
801 This is useful for determining how much space would be allotted for various
802 partitions with a labelling scheme using
808 .Dl disklabel64 -B da0s1
810 Install a new bootstrap on
812 The boot code comes from
816 On-disk and in-core labels are unchanged.
818 .Dl disklabel64 -w -B /dev/da0s1 -b newboot1 -s newboot2 da2212
820 Install a new label and bootstrap.
821 The label is derived from disktab information for
823 and installed both in-core and on-disk.
824 The bootstrap code comes from the files
829 .Dl dd if=/dev/zero of=/dev/da0 bs=512 count=32
831 .Dl dd if=/dev/zero of=/dev/da0s1 bs=512 count=32
832 .Dl disklabel64 -w -B da0s1 auto
833 .Dl disklabel64 -e da0s1
835 Completely wipe any prior information on the disk, creating a new bootable
836 disk with a DOS partition table containing one
840 initialize the slice, then edit it to your needs.
843 commands are optional, but may be necessary for some BIOSes to properly
846 This is an example disklabel that uses some of the new partition size types
851 which could be used as a source file for
853 .Dl disklabel64 -R ad0s1c new_label_file
854 .Bd -literal -offset 4n
863 sectors/cylinder: 1008
865 sectors/unit: 40959009
870 headswitch: 0 # milliseconds
871 track-to-track seek: 0 # milliseconds
884 The kernel device drivers will not allow the size of a disk partition
885 to be decreased or the offset of a partition to be changed while it is open.
886 Some device drivers create a label containing only a single large partition
887 if a disk is unlabeled; thus, the label must be written to the
889 partition of the disk while it is open.
890 This sometimes requires the desired
891 label to be set in two steps, the first one creating at least one other
892 partition, and the second setting the label on the new partition while shrinking
897 On some machines the bootstrap code may not fit entirely in the area
898 allocated for it by some file systems.
899 As a result, it may not be possible to have file systems on some partitions
903 When installing bootstrap code,
905 checks for these cases.
906 If the installed boot code would overlap a partition of type
912 utility will disallow creation of file systems on
915 Conversely, if a partition has a type other than
920 will not install bootstrap code that overlaps it.
931 When a disk name is given without a full pathname,
932 the constructed device name uses the
936 For the i386 architecture, the primary bootstrap sector contains
942 utility takes care to not clobber it when installing a bootstrap only
944 or when editing an existing label
946 but it unconditionally writes the primary bootstrap program onto
953 table by the dummy one in the bootstrap program.
955 concern if the disk is fully dedicated, so that the
958 starts at absolute block 0 on the disk.
963 does not perform all possible error checking.
964 Warning *is* given if partitions
965 overlap; if an absolute offset does not match the expected offset; if the
967 partition does not start at 0 or does not cover the entire slice; if a
968 partition runs past the end of the device; and a number of other errors; but
969 no warning is given if space remains unused.
projects / dragonfly.git / blob