.\" $FreeBSD: src/share/man/man4/wst.4,v 1.8.2.3 2001/12/21 10:07:09 ru Exp $ .\" $DragonFly: src/share/man/man4/Attic/wst.4,v 1.2 2003/06/17 04:36:59 dillon Exp $ .\" Copyright (c) 1998 .\" Warner Losh . 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 .Sh NAME .Nm wst .Nd ATAPI Tape drive .Sh SYNOPSIS .Cd options ATAPI .Cd device wst .Sh DESCRIPTION The .Nm 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 sa 4 or .Xr st 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 .Pa /dev/wst Ar Y Pa ctl. Ar X , .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 .An "S\(/oren Schmidt" Aq sos@sos.freebsd.dk wrote this driver which first appeared in .Fx 3.0 .