.\"	$OpenBSD: sd.4,v 1.4 2003/03/16 20:12:51 miod Exp $
.\"
.\" Copyright (c) 1996
.\"     Julian Elischer <julian@freebsd.org>.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
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.\"    notice, this list of conditions and the following disclaimer.
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.Dd January 18, 1996
.Dt SD 4 hp300
.Os
.Sh NAME
.Nm sd
.Nd SCSI disk driver
.Sh SYNOPSIS
.Cd "sd* at oscsi? target ? lun ?"
.Sh DESCRIPTION
The
.Nm
driver provides support for a
.Tn SCSI
disk.
It allows the disk to be divided up into a set of pseudo devices called
.Em partitions .
.Pp
When the
.Tn SCSI
adapter is probed during boot, the
.Tn SCSI
bus is scanned for devices.
Any devices found which answer as
.Sq Em Direct
type devices will be attached to the
.Nm
driver.
The devices will be attached as
.Li sdN
devices, matching their
.Tn SCSI
identifiers.
For example, a disk with
.Tn SCSI
id set to 6 will attach as
.Li sd6 .
.Sh PARTITIONING
.Xr disklabel 8
is used to partition the drive into filesystems.
.Sh IOCTLS
The following
.Xr ioctl 2
calls apply to
.Tn SCSI
disks as well as to other disks.
They are defined in the header file
.Aq Pa sys/disklabel.h .
.Pp
.Bl -tag -width DIOCSDINFO
.\".It Dv DIOCSBAD
.\"Usually used to set up a bad-block mapping system on the disk.
.\".Tn SCSI
.\"drive incorporate their own bad-block mapping so this command is not
.\"implemented.
.It Dv DIOCGDINFO
Read, from the kernel, the in-core copy of the disklabel for the
drive.
This may be a fictitious disklabel if the drive has never
been initialized, in which case it will contain information read
from the
.Tn SCSI
inquiry commands.
.It Dv DIOCSDINFO
Give the driver a new disklabel to use.
The driver
.Em will not
write the new
disklabel to the disk.
.It Dv DIOCWLABEL
Enable or disable the driver's software
write protect of the disklabel on the disk.
.It Dv DIOCWDINFO
Give the driver a new disklabel to use.
The driver
.Em will
write the new disklabel to the disk.
.It Dv DIOCLOCK
Lock the media cartridge into the device, or unlock a cartridge previously
locked.
Used to prevent user and software eject while the media is in use.
.It Dv DIOCEJECT
Eject the media cartridge from a removable device.
.El
.Pp
In addition, the
.Tn SCSI
general
.Fn ioctl
commands may be used with the
.Nm
driver, but only against the
.Sq Li c
(whole disk) partition.
.Sh NOTES
If a removable device is attached to the
.Nm
driver, then the act of changing the media will invalidate the
disklabel and information held within the kernel.
To avoid corruption, all access to the device will be discarded until there
are no more open file descriptors referencing the device.
During this period, all new open attempts will be rejected.
When no more open file descriptors reference the device, the next 
open will load a new set of parameters (including disklabel) for the drive.
.Sh FILES
.Bl -tag -width /dev/rsdXXXXX -compact
.It Pa /dev/sd Ns Ar u Ns Ar p
block mode
.Tn SCSI
disk unit
.Ar u ,
partition
.Ar p
.It Pa /dev/rsd Ns Ar u Ns Ar p
raw mode
.Tn SCSI
disk unit
.Ar u ,
partition
.Ar p
.Sm off
.El
.Sh SEE ALSO
.Xr \&ct 4 ,
.Xr hd 4 ,
.Xr intro 4 ,
.Xr oscsi 4 ,
.Xr st 4 ,
.Xr disklabel 5 ,
.Xr disklabel 8