.\"	$OpenBSD: disktab.5,v 1.19 2018/09/20 16:16:52 tb 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: September 20 2018 $
.Dt DISKTAB 5
.Os
.Sh NAME
.Nm disktab
.Nd disk description file
.Sh SYNOPSIS
.In disktab.h
.Sh DESCRIPTION
.Nm
is a simple database which describes disk geometries and
disk partition characteristics.
It is used
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 "d[0-4]" "bool" "Description"
.It Sy Name Ta Sy Type Ta Sy Description
.It \&dt Ta str Ta "Type of controller (e.g., SMD, ESDI, floppy)."
.It \&ns Ta num Ta "Number of sectors per track."
.It \&nt Ta num Ta "Number of tracks per cylinder."
.It \&nc Ta num Ta "Total number of cylinders on the disk."
.It \&sc Ta num Ta "Number of sectors per cylinder (default: ns*nt)."
.It \&su Ta num Ta "Number of sectors per unit (default: sc*nc)."
.It \&se Ta num Ta "Sector size in bytes (default:"
.Dv DEV_BSIZE ) .
.It \&sf Ta bool Ta "Controller supports bad144-style bad sector forwarding."
.It \&d[0-4] Ta num Ta "Drive-type-dependent parameters."
.It \&bs Ta num Ta "Boot block size (default:"
.Dv BBSIZE ) .
.It \&sb Ta num Ta "Superblock size (default: "
.Dv SBSIZE ) .
.Pp
.It \&ba Ta num Ta "Block size for partition"
.Dq a
(bytes).
.It \&bd Ta num Ta "Block size for partition"
.Dq d
(bytes).
.It \&be Ta num Ta "Block size for partition"
.Dq e
(bytes).
.It [...] Ta "" Ta ""
.It \&bp Ta num Ta "Block size for partition"
.Dq p
(bytes).
.Pp
.It \&fa Ta num Ta "Fragment size for partition"
.Dq a
(bytes).
.It \&fd Ta num Ta "Fragment size for partition"
.Dq d
(bytes).
.It \&fe Ta num Ta "Fragment size for partition"
.Dq e
(bytes).
.It [...] Ta "" Ta ""
.It \&fp Ta num Ta "Fragment size for partition"
.Dq p
(bytes).
.Pp
.It \&oa Ta num Ta "Offset of partition"
.Dq a
(sectors).
.It \&ob Ta num Ta "Offset of partition"
.Dq b
(sectors).
.It \&oc Ta num Ta "Offset of partition"
.Dq c
(sectors).
.It [...] Ta "" Ta ""
.It \&op Ta num Ta "Offset of partition"
.Dq p
(sectors).
.Pp
.It \&pa Ta num Ta "Size of partition"
.Dq a
(sectors).
.It \&pb Ta num Ta "Size of partition"
.Dq b
(sectors).
.It \&pc Ta num Ta "Size of partition"
.Dq c
(sectors).
.It [...] Ta "" Ta ""
.It \&pp Ta num Ta "Size of partition"
.Dq p
(sectors).
.Pp
.It \&ta Ta str Ta "Type of partition"
.Dq a
(4.2BSD, swap, etc.).
.It \&tb Ta str Ta "Type of partition"
.Dq b .
.It \&tc Ta str Ta "Type of partition"
.Dq c .
.It [...] Ta "" Ta ""
.It \&tp Ta str Ta "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 .