274 lines
7.2 KiB
Groff
274 lines
7.2 KiB
Groff
.\" $NetBSD: sd.4,v 1.16 2003/06/27 18:44:51 wiz Exp $
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.\"
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.\" Copyright (c) 1996
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.\" Julian Elischer <julian@freebsd.org>. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\"
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd January 18, 1996
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.Dt SD 4
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.Os
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.Sh NAME
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.Nm sd
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.Nd SCSI and ATAPI disk driver
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.Sh SYNOPSIS
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.Cd "sd* at scsibus? target ? lun ?"
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.Cd "sd3 at scsibus0 target 3 lun 0"
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.Cd "sd* at atapibus? drive ? flags 0x0000"
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for
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.Tn SCSI
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bus and Advanced Technology Attachment Packet Interface
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.Pq Tn ATAPI
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disks.
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It allows the disk to be divided up into a set of pseudo devices called
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.Em partitions .
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In general the interfaces are similar to those described by
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.Xr wd 4 .
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.Pp
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Where the
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.Xr wd 4
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device has a fairly low level interface to the system,
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.Tn SCSI
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devices have a much higher level interface and talk to the system via a
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.Tn SCSI
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host adapter
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(e.g.,
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.Xr ahc 4 ) .
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A
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.Tn SCSI
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adapter must also be separately configured into the system
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before a
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.Tn SCSI
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disk can be configured.
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.Pp
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When the
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.Tn SCSI
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adapter is probed during boot, the
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.Tn SCSI
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bus is scanned for devices.
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Any devices found which answer as
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.Sq Em Direct
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type devices will be attached to the
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.Nm
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driver.
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.Pp
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For the use of flags with ATAPI devices, see
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.Xr wd 4 .
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.\"In
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.\".Tn FreeBSD
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.\"releases prior to 2.1, the first found was attached as
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.\".Li sd0 ,
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.\"the second
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.\".Li sd1 ,
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.\"and so on.
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.\"Beginning in 2.1 it became possible to lock down the assignment of
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.\"devices on the
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.\".Tn SCSI
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.\"bus to particular units of the
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.\".Nm
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.\"device; refer to
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.\".Xr scsi 4
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.\"for details on kernel configuration.
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.Sh PARTITIONING
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.\"The
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.\".Nm
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.\"driver allows the disk to have two levels of partitioning.
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.\"One layer, called the
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.\".Dq slice layer ,
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.\"is used to separate the
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.\".Tn FreeBSD
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.\"areas of the disk from areas used by other operating systems.
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.\"The second layer is the native
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.\".Bx 4.4
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.\"partitioning scheme,
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.\".Xr disklabel 5 ,
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.\"which is used to subdivide the
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.\".Tn FreeBSD
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.\"slices into areas for individual filesystems and swap spaces.
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.\"For more information, see
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.\".Xr fdisk 8
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.\"and
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.\".Xr disklabel 8 ,
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.\"respectively.)
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On many systems
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.Xr disklabel 8
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is used to partition the drive into filesystems.
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On some systems the
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.Nx
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portion of the disk resides within a native partition, and another
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program is used to create the
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.Nx
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portion.
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.Pp
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For example, the i386 port uses
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.Xr fdisk 8
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to partition the disk into a
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.Tn BIOS
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level partition.
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This allows sharing the disk with other operating systems.
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.Pp
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.\"If an uninitialized disk is opened, the slice table will be
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.\"initialized with a fictitious
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.\".Tn FreeBSD
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.\"slice spanning the entire disk. Similarly, if an uninitialized
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.\"(or
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.\".No non- Ns Tn FreeBSD )
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.\"slice is opened, its disklabel will be initialized with parameters returned
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.\"by the drive and a single
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.\".Sq Li c
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.\"partition encompassing the entire slice.
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.\".Sh KERNEL CONFIGURATION
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.\"It is only necessary to explicitly configure one
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.\".Nm
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.\"device; data structures are dynamically allocated as disks are found
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.\"on the
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.\".Tn SCSI
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.\"bus.
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.Sh CONFIGURATION OPTIONS
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The following
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.Xr config 8
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options may be applied to
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.Tn SCSI
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disks as well as to other disks.
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.Pp
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.Bl -tag -width SD_IO_TIMEOUT
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.It Dv SDRETRIES
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Set the number of retries that will be performed for operations it
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makes sense to retry (e.g., normal reads and writes). The default
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is four (4).
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.It Dv SD_IO_TIMEOUT
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Set amount of time, in milliseconds, a normal read or write is expected
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to take. The defaults is sixty seconds (60000 milliseconds). This is used
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to set watchdog timers in the
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.Tn SCSI
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HBA driver to catch commands that might have died on the device.
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.El
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.Sh IOCTLS
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The following
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.Xr ioctl 2
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calls apply to
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.Tn SCSI
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disks as well as to other disks.
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They are defined in the header file
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.Aq Pa disklabel.h .
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.Pp
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.Bl -tag -width DIOCSDINFO
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.\".It Dv DIOCSBAD
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.\"Usually used to set up a bad-block mapping system on the disk.
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.\".Tn SCSI
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.\"drive incorporate their own bad-block mapping so this command is not
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.\"implemented.
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.It Dv DIOCGDINFO
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Read, from the kernel, the in-core copy of the disklabel for the drive.
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This may be a fictitious disklabel if the drive has never
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been initialized, in which case it will contain information read
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from the
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.Tn SCSI
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inquiry commands.
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.It Dv DIOCSDINFO
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Give the driver a new disklabel to use.
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The driver
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.Em will not
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write the new
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disklabel to the disk.
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.It Dv DIOCKLABEL
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Keep or drop the in-core disklabel on the last close.
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.It Dv DIOCWLABEL
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Enable or disable the driver's software
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write protect of the disklabel on the disk.
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.It Dv DIOCWDINFO
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Give the driver a new disklabel to use.
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The driver
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.Em will
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write the new disklabel to the disk.
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.It Dv DIOCLOCK
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Lock the media cartridge into the device, or unlock a cartridge previously
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locked.
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Used to prevent user and software eject while the media is in use.
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.It Dv DIOCEJECT
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Eject the media cartridge from a removable device.
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.El
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.Pp
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In addition, the
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.Xr scsi 4
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general
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.Fn ioctl
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commands may be used with the
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.Nm
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driver, but only against the
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.Sq Li c
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(whole disk) partition.
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.Sh NOTES
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If a removable device is attached to the
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.Nm
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driver, then the act of changing the media will invalidate the
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disklabel and information held within the kernel.
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To avoid corruption, all accesses to the device will be discarded
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until there are no more open file descriptors referencing the
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device.
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During this period, all new open attempts will be rejected.
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When no more open file descriptors reference the device, the first
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next open will load a new set of parameters (including disklabel)
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for the drive.
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.Sh FILES
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.Bl -tag -width /dev/rsdXXXXX -compact
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.It Pa /dev/sd Ns Ar u Ns Ar p
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block mode
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.Tn SCSI
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disk unit
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.Ar u ,
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partition
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.Ar p
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.It Pa /dev/rsd Ns Ar u Ns Ar p
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raw mode
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.Tn SCSI
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disk unit
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.Ar u ,
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partition
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.Ar p
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.El
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.Sh DIAGNOSTICS
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None.
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.Sh SEE ALSO
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.Xr ioctl 2 ,
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.Xr intro 4 ,
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.Xr scsi 4 ,
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.Xr wd 4 ,
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.Xr disklabel 5 ,
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.Xr disklabel 8 ,
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.Xr fdisk 8 ,
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.Xr scsictl 8
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.Sh HISTORY
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The
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.Nm
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driver was originally written for
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.Tn Mach
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2.5, and was ported to
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.Fx
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by Julian Elischer.
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It was later ported to
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.Nx .
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