xref: /freebsd/sbin/bsdlabel/bsdlabel.8 (revision b6de9e91bd2c47efaeec72a08642f8fd99cc7b20) 
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31.\"	@(#)disklabel.8	8.2 (Berkeley) 4/19/94
32.\" $FreeBSD$
33.\"
34.Dd March 15, 2003
35.Dt BSDLABEL 8
36.Os
37.Sh NAME
38.Nm bsdlabel
39.Nd read and write disk pack label
40.Sh SYNOPSIS
41.Nm
42.Op Fl A
43.Ar disk | Fl f Ar file
44.Nm
45.Fl w
46.Op Fl \&An
47.Op Fl B Op Fl b Ar boot
48.Op Fl m Ar machine
49.Ar disk | Fl f Ar file
50.Op Ar type
51.Nm
52.Fl e
53.Op Fl \&An
54.Op Fl B Op Fl b Ar boot
55.Op Fl m Ar machine
56.Ar disk | Fl f Ar file
57.Nm
58.Fl R
59.Op Fl \&An
60.Op Fl B Op Fl b Ar boot
61.Op Fl m Ar machine
62.Op Fl f
63.Ar disk | Fl f Ar file
64.Ar protofile
65.Sh DESCRIPTION
66The
67.Nm
68utility
69installs, examines or modifies the
70.Bx
71label on a disk partition, or on a file containing a partition image.
72In addition,
73.Nm
74can install bootstrap code.
75.Ss Disk Device Name
76When specifying the device (i.e., when the
77.Fl f
78option is not used),
79the
80.Pa /dev/
81path prefix may be omitted;
82the
83.Nm
84utility will automatically prepend it.
85.Ss General Options
86The
87.Fl A
88option enables processing of the historical parts of the
89.Bx
90label.
91If the option is not given, suitable values are set for these fields.
92.Pp
93The
94.Fl f
95option tells
96.Nm
97that the program will operate on a file instead of a disk partition.
98.Pp
99The
100.Fl n
101option stops the
102.Nm
103program right before the disk would have been modified, and displays
104the result instead of writing it.
105.Pp
106The
107.Fl m Ar machine
108argument forces
109.Nm
110to use a layout suitable for a different architecture.
111Current valid values are
112.Ar i386 ,
113.Ar amd64 ,
114.Ar ia64 ,
115.Ar pc98 ,
116and
117.Ar alpha .
118If this option is omitted,
119.Nm
120will use a layout suitable for the current machine.
121.Ss Reading the Disk Label
122To examine the label on a disk drive, use
123.Nm
124without options:
125.Pp
126.Nm
127.Op Fl A
128.Op Fl m Ar machine
129.Ar disk
130.Pp
131.Ar disk
132represents the disk in question, and may be in the form
133.Pa da0
134or
135.Pa /dev/da0 .
136It will display the partition layout.
137.Ss Writing a Standard Label
138To write a standard label, use the form
139.Pp
140.Nm
141.Fl w
142.Op Fl \&An
143.Op Fl m Ar machine
144.Ar disk
145.Op Ar type
146.Pp
147If the drive type is specified, the entry of that name in the
148.Xr disktab 5
149file is used; otherwise a default layout is used.
150.Ss Editing an Existing Disk Label
151To edit an existing disk label, use the form
152.Pp
153.Nm
154.Fl e
155.Op Fl \&An
156.Op Fl m Ar machine
157.Ar disk
158.Pp
159This command opens the disk label in the default editor, and when the editor
160exits, the label is validated and if OK written to disk.
161.Ss Restoring a Disk Label From a File
162To restore a disk label from a file, use the form
163.Pp
164.Nm
165.Fl R
166.Op Fl \&An
167.Op Fl m Ar machine
168.Ar disk protofile
169.Pp
170.Nm
171is capable of restoring a disk label that was previously saved in a file in
172.Tn ASCII
173format.
174The prototype file used to create the label should be in the same format as that
175produced when reading or editing a label.
176Comments are delimited by
177.Ql #
178and newline.
179.Ss Installing Bootstraps
180If the
181.Fl B
182argument is specified, bootstrap code will be read from the file
183.Pa /boot/boot
184and written to the disk.
185The
186.Fl b Ar boot
187argument allows a different file to be used.
188.Sh FILES
189.Bl -tag -width ".Pa /etc/disktab" -compact
190.It Pa /boot/boot
191Default boot image.
192.It Pa /etc/disktab
193Disk description file.
194.El
195.Sh SAVED FILE FORMAT
196The
197.Nm
198utility
199uses an
200.Tn ASCII
201version of the label when examining, editing, or restoring a disk
202label.
203The format is:
204.Bd -literal -offset 4n
205
2068 partitions:
207#        size   offset    fstype   [fsize bsize bps/cpg]
208  a:    81920        0    4.2BSD     1024  8192    16
209  b:   160000    81920      swap
210  c:  1173930        0    unused        0     0         # "raw" part, don't edit
211.Ed
212.Pp
213If the
214.Fl A
215option is specified, the format is:
216.Bd -literal -offset 4n
217# /dev/da1c:
218type: SCSI
219disk: da0s1
220label:
221flags:
222bytes/sector: 512
223sectors/track: 51
224tracks/cylinder: 19
225sectors/cylinder: 969
226cylinders: 1211
227sectors/unit: 1173930
228rpm: 3600
229interleave: 1
230trackskew: 0
231cylinderskew: 0
232headswitch: 0           # milliseconds
233track-to-track seek: 0  # milliseconds
234drivedata: 0
235
2368 partitions:
237#        size   offset    fstype   [fsize bsize bps/cpg]
238  a:    81920        0    4.2BSD     1024  8192    16
239  b:   160000    81920      swap
240  c:  1173930        0    unused        0     0         # "raw" part, don't edit
241.Ed
242.Pp
243Lines starting with a
244.Ql #
245mark are comments.
246.Pp
247The partition table can have up to 8 entries.
248It contains the following information:
249.Bl -tag -width indent
250.It Ar #
251The partition identifier is a single letter in the range
252.Ql a
253to
254.Ql h .
255By convention, partition
256.Ql c
257is reserved to describe the entire disk.
258.It Ar size
259The size of the partition in sectors,
260.Cm K
261(kilobytes - 1024),
262.Cm M
263(megabytes - 1024*1024),
264.Cm G
265(gigabytes - 1024*1024*1024),
266.Cm %
267(percentage of free space
268.Em after
269removing any fixed-size partitions other than partition
270.Ql c ) ,
271or
272.Cm *
273(all remaining free space
274.Em after
275fixed-size and percentage partitions).
276For partition
277.Ql c ,
278a size of
279.Cm *
280indicates the entire disk.
281Lowercase versions of
282.Cm K , M ,
283and
284.Cm G
285are allowed.
286Size and type should be specified without any spaces between them.
287.Pp
288Example: 2097152, 1G, 1024M and 1048576K are all the same size
289(assuming 512-byte sectors).
290.It Ar offset
291The offset of the start of the partition from the beginning of the
292drive in sectors, or
293.Cm *
294to have
295.Nm
296calculate the correct offset to use (the end of the previous partition plus
297one, ignoring partition
298.Ql c .
299For partition
300.Ql c ,
301.Cm *
302will be interpreted as an offset of 0.
303.It Ar fstype
304Describes the purpose of the partition.
305The example shows all currently used partition types.
306For
307.Tn UFS
308file systems and
309.Xr ccd 4
310partitions, use type
311.Cm 4.2BSD .
312For Vinum drives, use type
313.Cm vinum .
314Other common types are
315.Cm swap
316and
317.Cm unused .
318By convention, partition
319.Ql c
320represents the entire slice and should be of type
321.Cm unused ,
322though
323.Nm
324does not enforce this convention.
325The
326.Nm
327utility
328also knows about a number of other partition types,
329none of which are in current use.
330(See the definitions starting with
331.Dv FS_UNUSED
332in
333.In sys/disklabel.h
334for more details.)
335.It Ar fsize
336For
337.Cm 4.2BSD
338and
339.Tn LFS
340file systems only, the fragment size.
341Defaults to 1024 for partitions smaller than 1GB,
3424096 for partitions 1GB or larger.
343.It Ar bsize
344For
345.Cm 4.2BSD
346and
347.Tn LFS
348file systems only, the block size.
349Defaults to 8192 for partitions smaller than 1GB,
35016384 for partitions 1GB or larger.
351.It Ar bps/cpg
352For
353.Cm 4.2BSD
354file systems, the number of cylinders in a cylinder group.
355For
356.Tn LFS
357file systems, the segment shift value.
358Defaults to 16 for partitions smaller than 1GB,
35964 for partitions 1GB or larger.
360.El
361.Sh EXAMPLES
362.Dl "bsdlabel da0s1"
363.Pp
364Display the label for the first slice of the
365.Pa da0
366disk, as obtained via
367.Pa /dev/da0s1 .
368.Pp
369.Dl "bsdlabel da0s1 > savedlabel"
370.Pp
371Save the in-core label for
372.Pa da0s1
373into the file
374.Pa savedlabel .
375This file can be used with the
376.Fl R
377option to restore the label at a later date.
378.Pp
379.Dl "bsdlabel -w /dev/da0s1"
380.Pp
381Create a label for
382.Pa da0s1 .
383.Pp
384.Dl "bsdlabel -e da0s1"
385.Pp
386Read the label for
387.Pa da0s1 ,
388edit it, and install the result.
389.Pp
390.Dl "bsdlabel -e -n da0s1"
391.Pp
392Read the on-disk label for
393.Pa da0s1 ,
394edit it, and display what the new label would be (in sectors).
395It does
396.Em not
397install the new label either in-core or on-disk.
398.Pp
399.Dl "bsdlabel -w da0s1"
400.Pp
401Write a default label on
402.Pa da0s1 .
403Use another
404.Nm Fl e
405command to edit the
406partitioning and file system information.
407.Pp
408.Dl "bsdlabel -R da0s1 savedlabel"
409.Pp
410Restore the on-disk and in-core label for
411.Pa da0s1
412from information in
413.Pa savedlabel .
414.Pp
415.Dl "bsdlabel -R -n da0s1 label_layout"
416.Pp
417Display what the label would be for
418.Pa da0s1
419using the partition layout in
420.Pa label_layout .
421This is useful for determining how much space would be allotted for various
422partitions with a labeling scheme using
423.Cm % Ns -based
424or
425.Cm *
426partition sizes.
427.Pp
428.Dl "bsdlabel -B da0s1"
429.Pp
430Install a new bootstrap on
431.Pa da0s1 .
432The boot code comes from
433.Pa /boot/boot .
434.Pp
435.Dl "bsdlabel -w -B -b newboot /dev/da0s1"
436.Pp
437Install a new label and bootstrap.
438The bootstrap code comes from the file
439.Pa newboot
440in the current working directory.
441.Bd -literal -offset indent
442dd if=/dev/zero of=/dev/da0 bs=512 count=32
443fdisk -BI da0
444dd if=/dev/zero of=/dev/da0s1 bs=512 count=32
445bsdlabel -w -B da0s1
446bsdlabel -e da0s1
447.Ed
448.Pp
449Completely wipe any prior information on the disk, creating a new bootable
450disk with a
451.Tn DOS
452partition table containing one slice, covering the whole disk.
453Initialize the label on this slice,
454then edit it.
455The
456.Xr dd 1
457commands are optional, but may be necessary for some
458.Tn BIOS Ns es
459to properly
460recognize the disk.
461.Pp
462This is an example disk label that uses some of the new partition size types
463such as
464.Cm % , M , G ,
465and
466.Cm * ,
467which could be used as a source file for
468.Dq Li "bsdlabel -R ad0s1c new_label_file" :
469.Bd -literal -offset 4n
470# /dev/ad0s1c:
471
4728 partitions:
473#        size   offset    fstype   [fsize bsize bps/cpg]
474  a:   400M        0    4.2BSD     4096 16384    75 	# (Cyl.    0 - 812*)
475  b:     1G        *      swap
476  c:      *        *    unused
477  e: 204800        *    4.2BSD
478  f:     5g        *    4.2BSD
479  g:      *        *    4.2BSD
480.Ed
481.Sh DIAGNOSTICS
482The kernel device drivers will not allow the size of a disk partition
483to be decreased or the offset of a partition to be changed while it is open.
484.Sh COMPATIBILITY
485Due to the use of an
486.Vt u_int32_t
487to store the number of sectors,
488.Bx
489labels are restricted to a maximum of 2^32-1 sectors.
490This usually means 2TB of disk space.
491Larger disks should be partitioned using another method such as
492.Xr gpt 8 .
493.Pp
494The various
495.Bx Ns s
496all use slightly different versions of
497.Bx
498labels and
499are not generally compatible.
500.Sh SEE ALSO
501.Xr ccd 4 ,
502.Xr geom 4 ,
503.Xr md 4 ,
504.\" Xr bsdlabel 5 ,
505.Xr disktab 5 ,
506.Xr boot0cfg 8 ,
507.Xr fdisk 8 ,
508.Xr gpt 8
509