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disklabel(9s)
NAME
disklabel - Disk: Stores disk device label information
SYNOPSIS
struct disklabel {
u_int d_magic;
short d_type;
short d_subtype;
char d_typename[16];
union {
char un_d_packname[16];
struct {
char *un_d_boot0;
char *un_d_boot1;
} un_b;
} d_un;
u_int d_secsize;
u_int d_nsectors;
u_int d_ntracks;
u_int d_ncylinders;
u_int d_secpercyl;
u_int d_secperunit;
u_short d_sparespertrack;
u_short d_sparespercyl;
u_int d_acylinders;
u_short d_rpm;
u_short d_interleave;
u_short d_trackskew;
u_short d_cylskew;
u_int d_headswitch;
u_int d_trkseek;
u_int d_flags;
u_int d_drivedata[NDDATA];
u_int d_spare[NSPARE];
u_int d_magic2;
u_short d_checksum;
u_short d_npartitions;
u_int d_bbsize;
u_int d_sbsize;
struct partition {
u_int p_size;
u_int p_offset;
u_int p_fsize;
u_char p_fstype;
u_char p_frag;
u_short p_cpg;
} d_partitions[MAXPARTITIONS];
};
MEMBERS
d_magic
The magic number DISKMAGIC identifies this as a disklabel structure.
d_type
Specifies the type of driver. See the DESCRIPTION section for the
constants associated with the d_type member.
d_subtype
Specifies the device subtype specific to the controller or device type.
d_typename
Specifies up to a 16-character string array that gives the type name.
The following type name strings are recognized: unknown, SMD, MSCP, old
DEC, SCSI, ESDI, type 6, type 7, type 8, type 9, floppy, and SWXCR.
d_packname
Specifies the pack identifier returned when the disklabel is read off
the disk or in-core copy. The d_boot0 and d_boot1 #defines are the
(optional) names of the primary (block 0) and secondary (block 1-15)
bootstraps as found in /usr/mdec. These are returned when using
getdiskbyname to retrieve the values from /etc/disktab.
d_secsize
Specifies the number of bytes per sector.
d_nsectors
Specifies the number of data sectors per track.
d_ntracks
Specifies the number of tracks per cylinder.
d_ncylinders
Specifies the number of data cylinders per unit.
d_secpercyl
Specifies the number of data sectors per cylinder.
d_secperuniit
Specifies the number of data sectors per unit.
d_sparespertrack
Specifies the number of spare sectors per track. Spares are used for
bad sector replacements and are not counted in d_nsectors or
d_secpercyl. Spare sectors are assumed to be physical sectors occupying
space at the end of each track, cylinder, or both.
d_sparespercyl
Specifies the number of spare sectors per cylinder. Spares are used for
bad sector replacements and are not counted in d_nsectors or
d_secpercyl. Spare sectors are assumed to be physical sectors occupying
space at the end of each track, cylinder, or both.
d_acylinders
Specifies the number of alternate cylinders per unit. Alternate
cylinders include maintenance, replacement, and configuration
description areas.
d_rpm
Specifies rotational speed.
d_interleave
Specifies the physical sector interleave set up by the formatter or
controller when formatting. When interleaving is in use, logically
adjacent sectors are separated by some number of sectors, specified as
the ratio of physical sectors traversed per logical sector. Thus, an
interleave of 1:1 implies contiguous layout, while 2:1 implies that
logical sector 0 is separated by one sector from logical sector 1. This
member is used to compensate for a slow controller.
d_trackskew
Specifies the offset of sector 0 on a particular track relative to
sector 0 on the previous track on the same cylinder. This member is
used to compensate for a slow controller.
d_cylskew
Specifies the offset of sector 0 on a particular cylinder relative to
sector 0 on the previous cylinder. This member is used to compensate
for a slow controller.
d_headswitch
Specifies the head switch time in microseconds.
d_trkseek
Specifies track-to-track seek time in microseconds.
d_flags
Specifies the generic flags shared by various drives. See the
DESCRIPTION section for the flags associated with the d_flags member.
d_drivedata
Specifies an array of integers for storing information specific to the
drive type.
d_magic2
Specifies the magic number.
d_checksum
Specifies bitwise exclusive OR (XOR) of the data, including partitions.
d_npartitions
Specifies the number of partitions in the partition map.
d_bbsize
Specifies the size of the boot area in bytes.
d_sbsize
Specifies the size of the superblock in bytes.
d_partition
Specifies an array of structures, one per partition, containing the
following members:
·
p_size
Number of sectors in the partition
·
p_offset
Starting offset of the sector
·
p_fsize
File system basic fragment size
·
p_fstype
One of the following file system types: FS_UNUSED, FS_SWAP, FS_V6,
FS_V7, FS_SYSV, FS_V71K, FS_V8, FS_BSDFFS, FS_ADVFS, FS_LSMpubl,
FS_LSMpriv, and FS_LSMsimp. See the DESCRIPTION section for
additional information on these constants.
·
p_frag
File system fragments per block
·
p_cpg
File system cylinders per group
DESCRIPTION
Each disk has a label that includes information about the hardware disk
geometry, file system partitions, and drive-specific information. The label
is in block 0 or 1, possibly offset from the beginning to leave room for
bootstrap information. A device driver uses the LABELSECTOR and LABELOFFSET
constants to refer to the location of the label.
The disklabel structure is accessed by the disk device driver's open
interface to set up the default geometry and partition 0 on the disk. The
DIOCGDINFO and DIOCGPART ioctl commands use this structure to return the
disklabel and partition structures; the DIOCSDINFO and DIOCWDINFO ioctl
commands to set or write the contents of the structure.
The d_type member takes one of the following drive type constants:
DTYPE_SMD
SMD, XSMD, VAX hp/up
DTYPE_MSCP
MSCP
DTYPE_DEC
DEC (rk, rl)
DTYPE_SCSI
SCSI
DTYPE_ESDI
ESDI interface
DTYPE_ST506
ST506 etc.
DTYPE_FLOPPY
floppy diskette
DTYPE_SWXCR
StorageWorks (RAID)
The d_flags member takes one of the following flags:
D_REMOVABLE
Removable media
D_ECC Supports ECC
D_RAMDISK
Disk emulator
D_CHAIN Supports back-to-back transfers
D_DYNAM_GEOM
Dynamic geometry device
The p_fstype member of the d_partitions member takes one of the following
file system types:
FS_UNUSED
Unused
FS_SWAP Swap
FS_V6 Sixth edition
FS_V7 Seventh edition
FS_SYSV System V
FS_V71K Version 7, 1K blocks
FS_V8 8th edition, 4K blocks
FS_BSDFFS
4.2BSD, fast file system
FS_ADVFS
Advanced File System
FS_LSMpubl
Logical Storage Manager, public region
FS_LSMpriv
Logical Storage Manager, private region
FS_LSMsimp
Logical Storage Manager, simple disk
FILES
<sys/disklabel.h>
SEE ALSO
Kernel Interfaces: readdisklabel(9r), setdisklabel(9r), writedisklabel(9r)
ioctl Commands: DIOCGDINFO(9r), DIOCGPART(9r), DIOCSDINFO(9r),
DIOCWDINFO(9r)
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Index for
Section 9 |
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Alphabetical
listing for D |
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Top of
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