231 lines
8.8 KiB
Groff
231 lines
8.8 KiB
Groff
.\" $FreeBSD$
|
|
.\" Copyright (c) 1998
|
|
.\" Warner Losh <imp@village.org>. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\"
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.Dd August 27, 1998
|
|
.Dt WST 4
|
|
.Os FreeBSD
|
|
.Sh NAME
|
|
.Nm wst
|
|
.Nd ATAPI Tape drive
|
|
.Sh SYNOPSIS
|
|
.Cd options ATAPI
|
|
.Cd device wst0
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Mn
|
|
driver provides support for a
|
|
.Tn atapi
|
|
tape drive connected to an
|
|
.Tn IDE
|
|
bus. It allows the tape to be run in up to four different modes
|
|
depending on minor numbers and supports several different `sub-modes'.
|
|
The device can have both a
|
|
.Em raw
|
|
interface and a
|
|
.Em block
|
|
interface; however, only the raw interface is usually used (or
|
|
recommended). In general the interfaces are similar to those
|
|
described by
|
|
.Xr st 4
|
|
or
|
|
.Xr mt 4 .
|
|
.Pp
|
|
An IDE adapter must also be configured into the kernel before the tape
|
|
drive can be configured. In addition, ATAPI must be enabled in the
|
|
kernel as well.
|
|
.Sh MOUNT SESSIONS
|
|
The
|
|
.Nm
|
|
driver is based around the concept of a
|
|
.Dq Em mount session ,
|
|
which is defined as the period between the time that a tape is
|
|
mounted, and the time when it is unmounted. Any parameters set during
|
|
a mount session remain in effect for the remainder of the session or
|
|
until replaced. The tape can be unmounted, bringing the session to a
|
|
close in several ways. These include:
|
|
.Bl -enum
|
|
.It
|
|
Closing an `unmount device',
|
|
referred to as sub-mode 00 below. An example is
|
|
.Pa /dev/rwst0 .
|
|
.It
|
|
Using the MTOFFL
|
|
.Xr ioctl 2
|
|
command, reachable through the
|
|
.Sq Cm offline
|
|
command of
|
|
.Xr wst 1 .
|
|
.It
|
|
Opening a different mode will implicitly unmount the tape, thereby closing
|
|
off the mode that was previously mounted. All parameters will be loaded
|
|
freshly from the new mode. (See below for more on modes.)
|
|
.El
|
|
.Pp
|
|
Parameters that are required to last across the unmounting of a tape
|
|
should be set on the control device. This is sub-mode 3 (see below) and is
|
|
reached through a file with a name of the form
|
|
.Sm off
|
|
.No Xo
|
|
.Pa /dev/wst
|
|
.Ar Y
|
|
.Pa ctl.
|
|
.Ar X
|
|
.Xc ,
|
|
.Sm on
|
|
where
|
|
.Ar Y
|
|
is the drive number and
|
|
.Ar X
|
|
is the mode number.
|
|
.Sh MODES AND SUB-MODES
|
|
There are four
|
|
.Sq operation
|
|
modes. These are controlled by bits 2 and 3 of the minor number and
|
|
are designed to allow users to easily read and write different formats
|
|
of tape on devices that allow multiple formats. The parameters for
|
|
each mode can be set individually by hand with the
|
|
.Xr mt 1
|
|
command. When a device corresponding to a particular mode is first
|
|
mounted, the operating parameters for that
|
|
mount session
|
|
are copied from that mode. Further changes to the parameters during the
|
|
session will change those in effect for the session but not those set
|
|
in the operation mode. To change the parameters for an operation mode,
|
|
one must either assign the parameters to the control device.
|
|
.Pp
|
|
In addition to the four operating modes mentioned above,
|
|
bits 0 and 1 of the minor number are interpreted as
|
|
.Sq sub-modes .
|
|
The sub-modes differ in the action taken when the device is closed:
|
|
.Bl -tag -width XXXX
|
|
.It 00
|
|
A close will rewind the device; if the tape has been
|
|
written, then a file mark will be written before the rewind is requested.
|
|
The device is unmounted.
|
|
.It 01
|
|
A close will leave the tape mounted.
|
|
If the tape was written to, a file mark will be written.
|
|
No other head positioning takes place.
|
|
Any further reads or writes will occur directly after the
|
|
last read, or the written file mark.
|
|
.It 10
|
|
A close will rewind the device. If the tape has been
|
|
written, then a file mark will be written before the rewind is requested.
|
|
On completion of the rewind an unload command will be issued.
|
|
The device is unmounted.
|
|
.It 11
|
|
This is a special mode, known as the
|
|
.Dq control device
|
|
for the mode. Parameters set for the mode while in this sub-mode will
|
|
be remembered from one mount to the next. This allows the system
|
|
administrator to set different characteristics (e.g., density,
|
|
blocksize and eventually compression)
|
|
on each mode, and have the different modes keep those parameters
|
|
independent of any parameter changes a user may invoke during a single
|
|
mount session. At the completion of the user's mount session, drive
|
|
parameters will revert to those set by the administrator. I/O
|
|
operations cannot be performed on this device/sub-mode.
|
|
.El
|
|
.Sh BLOCKING MODES
|
|
.Tn ATAPI
|
|
tapes may run in either
|
|
.Sq Em variable
|
|
or
|
|
.Sq Em fixed
|
|
block-size modes. Most
|
|
.Tn QIC Ns -type
|
|
devices run in fixed block-size mode, where most nine-track tapes and
|
|
many new cartridge formats allow variable block-size. The difference
|
|
between the two is as follows:
|
|
.Bl -inset
|
|
.It Variable block-size:
|
|
Each write made to the device results in a single logical record
|
|
written to the tape. One can never read or write
|
|
.Em part
|
|
of a record from tape (though you may request a larger block and read
|
|
a smaller record); nor can one read multiple blocks. Data from a
|
|
single write is therefore read by a single read. The block size used
|
|
may be any value supported by the device, the
|
|
.Tn IDE
|
|
controller and the system (usually between 1 byte and 64 Kbytes,
|
|
sometimes more).
|
|
.Pp
|
|
When reading a variable record/block from the tape, the head is
|
|
logically considered to be immediately after the last item read,
|
|
and before the next item after that. If the next item is a file mark,
|
|
but it was never read, then the next
|
|
process to read will immediately hit the file mark and receive an end-of-file notification.
|
|
.It Fixed block-size
|
|
Data written by the user is passed to the tape as a succession of
|
|
fixed size blocks. It may be contiguous in memory, but it is
|
|
considered to be a series of independent blocks. One may never write
|
|
an amount of data that is not an exact multiple of the blocksize. One
|
|
may read and write the same data as a different set of records, In
|
|
other words, blocks that were written together may be read separately,
|
|
and vice-versa.
|
|
.Pp
|
|
If one requests more blocks than remain in the file, the drive will
|
|
encounter the file mark. Because there is some data to return (unless
|
|
there were no records before the file mark), the read will succeed,
|
|
returning that data. The next read will return immediately with an
|
|
EOF. (As above, if the file mark is never read, it remains for the next process to read if in no-rewind mode.)
|
|
.El
|
|
.Sh FILE MARK HANDLING
|
|
The handling of file marks on write is automatic. If the user has
|
|
written to the tape, and has not done a read since the last write,
|
|
then a file mark will be written to the tape when the device is
|
|
closed. If a rewind is requested after a write, then the driver
|
|
assumes that the last file on the tape has been written, and ensures
|
|
that there are two file marks written to the tape. The exception to
|
|
this is that there seems to be a standard (which we follow, but don't
|
|
understand why) that certain types of tape do not actually write two
|
|
file marks to tape, but when read, report a `phantom' file mark when the
|
|
last file is read. These devices include the QIC family of devices.
|
|
(It might be that this set of devices is the same set as that of fixed
|
|
block devices. This has not been determined yet, and they are treated
|
|
as separate behaviors by the driver at this time.)
|
|
.Sh KERNEL CONFIGURATION
|
|
In configuring, if an optional
|
|
.Ar count
|
|
is given in the specification, that number of tape devices are configured.
|
|
.Pp
|
|
.Sh NOTES
|
|
Some motherboards and IDE controllers are out of spec when it comes to
|
|
certain minor, but critical to tape, sections of ATAPI spec. These
|
|
motherboards are mostly rare, with the exception of the Natoma 440FX
|
|
chipset found on Pentium Pro motherboards.
|
|
.Sh FILES
|
|
.Bl -tag -width /dev/wst[0-9] -compact
|
|
.It Pa /dev/wst[0-9]
|
|
device entries
|
|
.El
|
|
.Sh DIAGNOSTICS
|
|
None.
|
|
.Sh HISTORY
|
|
Soren Schmidt <sos@sos.freebsd.dk> wrote this driver which first
|
|
appeared in
|
|
.Fx 3.0 .
|