1.\" Copyright (c) 1987, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Symmetric Computer Systems. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 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. 22.\" 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 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)disklabel.5.5 8.1 (Berkeley) 6/5/93 36.\" $FreeBSD: src/sbin/disklabel/disklabel.5,v 1.7.2.4 2002/08/21 18:58:16 trhodes Exp $ 37.\" $DragonFly: src/sbin/disklabel64/disklabel64.5,v 1.2 2007/08/10 18:28:27 swildner Exp $ 38.\" 39.Dd June 5, 1993 40.Dt DISKLABEL64 5 41.Os 42.Sh NAME 43.Nm disklabel64 44.Nd disk pack label 45.Sh SYNOPSIS 46.In sys/disklabel64.h 47.Sh DESCRIPTION 48Each disk or disk pack on a system may contain a disk label 49which provides detailed information 50about the geometry of the disk and the partitions into which the disk 51is divided. 52It should be initialized when the disk is formatted, 53and may be changed later with the 54.Xr disklabel64 8 55program. 56This information is used by the system disk driver and by the bootstrap 57program to determine how to program the drive 58and where to find the file systems on the disk partitions. 59Additional information is used by the file system in order 60to use the disk most efficiently and to locate important file system information. 61The description of each partition contains an identifier for the partition 62type (standard file system, swap area, etc.). 63The file system updates the in-core copy of the label if it contains 64incomplete information about the file system. 65.Pp 66The label is located in sector number 67.Dv LABELSECTOR 68of the drive, usually sector 0 where it may be found 69without any information about the disk geometry. 70It is at an offset 71.Dv LABELOFFSET 72from the beginning of the sector, to allow room for the initial bootstrap. 73The disk sector containing the label is normally made read-only 74so that it is not accidentally overwritten by pack-to-pack copies 75or swap operations; 76the 77.Dv DIOCWLABEL 78.Xr ioctl 2 , 79which is done as needed by the 80.Xr disklabel64 8 81program. 82.Pp 83A copy of the in-core label for a disk can be obtained with the 84.Dv DIOCGDINFO 85.Xr ioctl 2 ; 86this works with a file descriptor for a block or character (``raw'') device 87for any partition of the disk. 88The in-core copy of the label is set by the 89.Dv DIOCSDINFO 90.Xr ioctl 2 . 91The offset of a partition cannot generally be changed while it is open, 92nor can it be made smaller while it is open. 93One exception is that any change is allowed if no label was found 94on the disk, and the driver was able to construct only a skeletal label 95without partition information. 96Finally, the 97.Dv DIOCWDINFO 98.Xr ioctl 2 99operation sets the in-core label and then updates the on-disk label; 100there must be an existing label on the disk for this operation to succeed. 101Thus, the initial label for a disk or disk pack must be installed 102by writing to the raw disk. 103All of these operations are normally done using 104.Xr disklabel64 8 . 105.Pp 106The format of the disk label is specified in 107.In sys/disklabel64.h . 108.Sh SEE ALSO 109.Xr disklabel 5 , 110.Xr disktab 5 , 111.Xr disklabel64 8 112