.\"	$OpenBSD: disktab.5,v 1.12 2007/05/31 19:19:58 jmc Exp $
.\"	$NetBSD: disktab.5,v 1.4 1994/11/30 19:31:15 jtc Exp $
.\"
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.\"     @(#)disktab.5	8.1 (Berkeley) 6/5/93
.\"
.Dd $Mdocdate: May 31 2007 $
.Dt DISKTAB 5
.Os
.Sh NAME
.Nm disktab
.Nd disk description file
.Sh SYNOPSIS
.Fd #include <disktab.h>
.Sh DESCRIPTION
.Nm
is a simple database which describes disk geometries and
disk partition characteristics.
It is used
.\"by the formatter(\c
.\"IR.Xr format 8 )
.\"to determine how to format the disk, and
to initialize the disk label on the disk.
The format is patterned after the
.Xr termcap 5
terminal database.
Entries in
.Nm
consist of a number of colon
.Pq Ql \&:
separated fields.
The first entry for each disk gives the names which are
known for the disk, separated by
.Dq \&|
characters.
The last name given should be a long name fully identifying the disk.
.Pp
The following list indicates the normal values stored for each disk entry:
.Bl -column "indent" "boolx"
.It Sy Name	Type	Description
.It "\&ty	str	Type of disk (e.g., removable, winchester)."
.It "\&dt	str	Type of controller (e.g.,"
.Tn SMD , ESDI ,
floppy).
.It "\&ns	num	Number of sectors per track."
.It "\&nt	num	Number of tracks per cylinder."
.It "\&nc	num	Total number of cylinders on the disk."
.It "\&sc	num	Number of sectors per cylinder (default: ns*nt)."
.It "\&su	num	Number of sectors per unit (default: sc*nc)."
.It "\&se	num	Sector size in bytes (default:"
.Dv DEV_BSIZE ) .
.It "\&sf	bool	Controller supports bad144-style bad sector forwarding."
.It "\&rm	num	Rotation speed in RPM (default: 3600)."
.It "\&sk	num	Sector skew per track (default: 0)."
.It "\&cs	num	Sector skew per cylinder (default: 0)."
.It "\&hs	num	Headswitch time in usec (default: 0)."
.It "\&ts	num	One-cylinder seek time in usec (default: 0)."
.It "\&il	num	Sector interleave (n:1) (default: 1)."
.It "\&d[0-4]	num	Drive-type-dependent parameters."
.It "\&b0	str	Pathname to primary bootstrap."
.It "\&b1	str	Pathname to secondary bootstrap."
.It "\&bs	num	Boot block size (default:"
.Dv BBSIZE ) .
.It "\&sb	num	Superblock size (default: "
.Dv SBSIZE ) .
.Pp
.It "\&ba	num	Block size for partition"
.Dq a
(bytes).
.It "\&bd	num	Block size for partition"
.Dq d
(bytes).
.It "\&be	num	Block size for partition"
.Dq e
(bytes).
.It [...]
.It "\&bp	num	Block size for partition"
.Dq p
(bytes).
.Pp
.It "\&fa	num	Fragment size for partition"
.Dq a
(bytes).
.It "\&fd	num	Fragment size for partition"
.Dq d
(bytes).
.It "\&fe	num	Fragment size for partition"
.Dq e
(bytes).
.It [...]
.It "\&fp	num	Fragment size for partition"
.Dq p
(bytes).
.Pp
.It "\&oa	num	Offset of partition"
.Dq a
(sectors).
.It "\&ob	num	Offset of partition"
.Dq b
(sectors).
.It "\&oc	num	Offset of partition"
.Dq c
(sectors).
.It [...]
.It "\&op	num	Offset of partition"
.Dq p
(sectors).
.Pp
.It "\&pa	num	Size of partition"
.Dq a
(sectors).
.It "\&pb	num	Size of partition"
.Dq b
(sectors).
.It "\&pc	num	Size of partition"
.Dq c
(sectors).
.It [...]
.It "\&pp	num	Size of partition"
.Dq p
(sectors).
.Pp
.It "\&ta	str	Type of partition"
.Dq a
(4.2BSD, swap, etc.).
.It "\&tb	str	Type of partition"
.Dq b .
.It "\&tc	str	Type of partition"
.Dq c .
.It [...]
.It "\&tp	str	Type of partition"
.Dq p .
.El
.Sh FILES
.Bl -tag -width /etc/disktab -compact
.It Pa /etc/disktab
.El
.Sh SEE ALSO
.Xr getdiskbyname 3 ,
.Xr disklabel 5 ,
.Xr disklabel 8 ,
.Xr newfs 8
.Sh HISTORY
The
.Nm
description file appeared in
.Bx 4.2 .