projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 37adbef5 MK |
1 | .\" from Symmetric Computer Systems. |
| 2 | .\" Modifications Copyright (c) 1987 Regents of the University of California. | |
| 3 | .\" All rights reserved. The Berkeley software License Agreement | |
| 4 | .\" specifies the terms and conditions for redistribution. | |
| 5 | .\" | |
| afbc24d7 | 6 | .\" @(#)disklabel.5.5 6.2 (Berkeley) %G% |
| 37adbef5 MK |
7 | .\" |
| 8 | .TH DISKLABEL 5 "" | |
| 9 | .UC 7 | |
| 10 | .SH NAME | |
| 11 | disklabel \- disk pack label | |
| 12 | .SH SYNOPSIS | |
| 13 | .B #include <sys/disklabel.h> | |
| 14 | .SH DESCRIPTION | |
| 15 | Each disk or disk pack on a system may contain a disk label | |
| 16 | which provides detailed information | |
| 17 | about the geometry of the disk and the partitions into which the disk | |
| 18 | is divided. | |
| 19 | It should be initialized when the disk is formatted, | |
| 20 | and may be changed later with the | |
| 21 | .IR disklabel (8) | |
| 22 | program. | |
| 23 | This information is used by the system disk driver and by the bootstrap | |
| 24 | program to determine how to program the drive | |
| 25 | and where to find the filesystems on the disk partitions. | |
| 26 | Additional information is used by the filesystem in order | |
| 27 | to use the disk most efficiently and to locate important filesystem information. | |
| afbc24d7 MK |
28 | The description of each partition contains an identifier for the partition |
| 29 | type (standard filesystem, swap area, etc.). | |
| 30 | The filesystem updates the in-core copy of the label if it contains | |
| 31 | incomplete information about the filesystem. | |
| 32 | .PP | |
| 37adbef5 MK |
33 | The label is located in sector number |
| 34 | .I LABELSECTOR | |
| 35 | of the drive, usually sector 0 where it may be found | |
| 36 | without any information about the disk geometry. | |
| 37 | It is at an offset | |
| 38 | .I LABELOFFSET | |
| 39 | from the beginning of the sector, to allow room for the initial bootstrap. | |
| afbc24d7 MK |
40 | The disk sector containing the label is normally made read-only |
| 41 | so that it is not accidentally overwritten by pack-to-pack copies | |
| 42 | or swap operations; | |
| 43 | the DIOCWLABEL | |
| 44 | .IR ioctl , | |
| 45 | which is done as needed by the | |
| 46 | .IR disklabel (8) | |
| 47 | program. | |
| 48 | .PP | |
| 49 | A copy of the in-core label for a disk can be obtained with the DIOCGDINFO | |
| 50 | .IR ioctl ; | |
| 51 | this works with a file descriptor for a block or character (``raw'') device | |
| 52 | for any partition of the disk. | |
| 53 | The in-core copy of the label is set by the DIOCSDINFO | |
| 54 | .IR ioctl . | |
| 55 | The offset of a partition cannot generally be changed while it is open, | |
| 56 | nor can it be made smaller while it is open. | |
| 57 | One exception is that any change is allowed if no label was found | |
| 58 | on the disk, and the driver was able to construct only a skeletal label | |
| 59 | without partition information. | |
| 60 | Finally, the DIOCWDINFO | |
| 61 | .I ioctl | |
| 62 | operation sets the in-core label and then updates the on-disk label; | |
| 63 | there must be an existing label on the disk for this operation to succeed. | |
| 64 | Thus, the initial label for a disk or disk pack must be installed | |
| 65 | by writing to the raw disk. | |
| 66 | All of these operations are normally done using | |
| 67 | .IR disklabel (8). | |
| 68 | .PP | |
| 37adbef5 MK |
69 | The format of the disk label, as specified in |
| 70 | .RI < sys/disklabel.h >, | |
| 71 | is | |
| 72 | .nf | |
| 73 | .DT | |
| 74 | .so /usr/include/sys/disklabel.h | |
| 75 | .SH "SEE ALSO" | |
| 76 | disktab(5), disklabel(8) |