405 lines
13 KiB
Groff
405 lines
13 KiB
Groff
.\" Copyright (c) 1981, 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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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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.\" 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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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.\" @(#)mt.1 8.1 (Berkeley) 6/6/93
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.\" $FreeBSD$
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.\"
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.Dd January 20, 2008
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.Dt MT 1
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.Os
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.Sh NAME
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.Nm mt
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.Nd magnetic tape manipulating program
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.Sh SYNOPSIS
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.Nm
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.Op Fl f Ar tapename
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.Ar command
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.Op Ar count
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.Nm
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.Op Fl f Ar tapename
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.Ar command
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.Ar argument
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.Sh DESCRIPTION
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The
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.Nm
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utility is used to command a magnetic tape drive for operations
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other than reading or writing data.
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.Pp
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The
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.Fl f
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option's
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.Ar tapename
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overrides the
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.Ev TAPE
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environment variable described below.
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.Pp
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The available commands are listed below.
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Only as many
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characters as are required to uniquely identify a command
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need be specified.
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.Pp
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The following commands optionally take a
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.Ar count ,
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which defaults to 1.
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.Bl -tag -width ".Cm erase"
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.It Cm weof
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Write
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.Ar count
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end-of-file (EOF) marks at the current position.
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.It Cm smk
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Write
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.Ar count
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setmarks at the current position (DDS drives only).
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.It Cm fsf
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Forward space
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.Ar count
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files.
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.It Cm fsr
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Forward space
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.Ar count
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records.
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.It Cm fss
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Forward space
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.Ar count
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setmarks (DDS drives only).
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.It Cm bsf
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Backward space
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.Ar count
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files.
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.It Cm bsr
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Backward space
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.Ar count
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records.
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.It Cm bss
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Backward space
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.Ar count
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setmarks (DDS drives only).
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.It Cm erase
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Erase the tape using a long (often very long) method.
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With a
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.Ar count
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of 0, it will erase the tape using a quick method.
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Operation is not guaranteed if the tape is not at its beginning.
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The tape will be at its beginning upon completion.
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.El
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.Pp
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The following commands ignore
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.Ar count .
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.Bl -tag -width ".Cm geteotmodel"
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.It Cm rdhpos
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Read the hardware block position.
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The block
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number reported is specific for that hardware only.
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With drive data compression especially,
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this position may have more to do with the amount of data
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sent to the drive than the amount of data written to tape.
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Some drives do not support this.
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.It Cm rdspos
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Read the SCSI logical block position.
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This typically is greater than the hardware position
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by the number of end-of-file marks.
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Some drives do not support this.
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.It Cm rewind
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Rewind the tape.
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.It Cm offline , rewoffl
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Rewind the tape and place the drive off line.
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Some drives are never off line.
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.It Cm retension
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Re-tension the tape.
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This winds the tape from the current position to the end
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and then to the beginning.
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This sometimes improves subsequent reading and writing,
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particularly for streaming drives.
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Some drives do not support this.
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.It Cm status
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Output status information about the drive.
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For SCSI magnetic tape devices,
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the current operating modes of density, blocksize, and whether compression
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is enabled is reported.
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The current state of the driver (what it thinks that
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it is doing with the device) is reported.
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If the driver knows the relative
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position from BOT (in terms of filemarks and records), it outputs that.
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Note
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that this information is not definitive (only BOT, End of Recorded Media, and
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hardware or SCSI logical block position (if the drive supports such) are
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considered definitive tape positions).
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.It Cm errstat
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Output (and clear) error status information about this device.
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For every normal
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operation (e.g., a read or a write) and every control operation (e.g,, a
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rewind), the driver stores up the last command executed and it is associated
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status and any residual counts (if any).
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This command retrieves and outputs this
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information.
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If possible, this also clears any latched error information.
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.It Cm geteotmodel
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Output the current EOT filemark model.
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The model states how
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many filemarks will be written at close if a tape was being written.
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.It Cm eod , eom
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Wind the tape to the end of the recorded data,
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typically after an EOF mark where another file may be written.
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.El
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.Pp
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The following commands require an
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.Ar argument .
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.Bl -tag -width ".Cm seteotmodel"
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.It Cm sethpos
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Set the hardware block position.
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The
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.Ar argument
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is a hardware block number to which to position the tape.
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Some drives do not support this.
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.It Cm setspos
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Set the SCSI logical block position.
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The
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.Ar argument
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is a SCSI logical block number to which to position the tape.
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Some drives do not support this.
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.It Cm blocksize
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Set the block size for the drive.
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The
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.Ar argument
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is the number of bytes per block,
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except 0 commands the drive to use variable-length blocks.
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.It Cm seteotmodel
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Set the EOT filemark model to
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.Ar argument
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and output the old and new models.
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Typically this will be 2
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filemarks, but some devices (typically QIC cartridge drives) can
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only write 1 filemark.
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You may only choose a value of
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.Ar 1
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or
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.Ar 2 .
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.It Cm comp
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Set the drive's compression mode.
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The non-numeric values of
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.Ar argument
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are:
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.Pp
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.Bl -tag -width 9n -compact
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.It off
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Turn compression off.
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.It on
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Turn compression on.
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.It none
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Same as
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.Ar off .
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.It enable
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Same as
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.Ar on .
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.It IDRC
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IBM Improved Data Recording Capability compression (0x10).
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.It DCLZ
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DCLZ compression algorithm (0x20).
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.El
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.Pp
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In addition to the above recognized compression keywords, the user can
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supply a numeric compression algorithm for the drive to use.
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In most
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cases, simply turning the compression
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.Sq on
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will have the desired effect of enabling the default compression algorithm
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supported by the drive.
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If this is not the case (see the
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.Cm status
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display to see which compression algorithm is currently in use), the user
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can manually specify one of the supported compression keywords (above), or
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supply a numeric compression value from the drive's specifications.
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.It Cm density
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Set the density for the drive.
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For the density codes, see below.
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The density value could be given either numerically, or as a string,
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corresponding to the
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.Dq Reference
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field.
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If the string is abbreviated, it will be resolved in the order
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shown in the table, and the first matching entry will be used.
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If the
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given string and the resulting canonical density name do not match
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exactly, an informational message is output about what the given
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string has been taken for.
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.El
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.Pp
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The following density table was taken from the
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.Sq Historical sequential access density codes
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table (A-1) in Revision 11 of the SCSI-3 Stream Device Commands (SSC)
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working draft, dated November 11, 1997.
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.Pp
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The density codes are:
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.Bd -literal -offset 3n
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0x0 default for device
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0xE reserved for ECMA
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Value Width Tracks Density Code Type Reference Note
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mm in bpmm bpi
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0x01 12.7 (0.5) 9 32 (800) NRZI R X3.22-1983 2
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0x02 12.7 (0.5) 9 63 (1,600) PE R X3.39-1986 2
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0x03 12.7 (0.5) 9 246 (6,250) GCR R X3.54-1986 2
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0x05 6.3 (0.25) 4/9 315 (8,000) GCR C X3.136-1986 1
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0x06 12.7 (0.5) 9 126 (3,200) PE R X3.157-1987 2
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0x07 6.3 (0.25) 4 252 (6,400) IMFM C X3.116-1986 1
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0x08 3.81 (0.15) 4 315 (8,000) GCR CS X3.158-1987 1
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0x09 12.7 (0.5) 18 1,491 (37,871) GCR C X3.180 2
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0x0A 12.7 (0.5) 22 262 (6,667) MFM C X3B5/86-199 1
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0x0B 6.3 (0.25) 4 63 (1,600) PE C X3.56-1986 1
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0x0C 12.7 (0.5) 24 500 (12,690) GCR C HI-TC1 1,6
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0x0D 12.7 (0.5) 24 999 (25,380) GCR C HI-TC2 1,6
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0x0F 6.3 (0.25) 15 394 (10,000) GCR C QIC-120 1,6
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0x10 6.3 (0.25) 18 394 (10,000) GCR C QIC-150 1,6
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0x11 6.3 (0.25) 26 630 (16,000) GCR C QIC-320 1,6
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0x12 6.3 (0.25) 30 2,034 (51,667) RLL C QIC-1350 1,6
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0x13 3.81 (0.15) 1 2,400 (61,000) DDS CS X3B5/88-185A 5
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0x14 8.0 (0.315) 1 1,703 (43,245) RLL CS X3.202-1991 5
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0x15 8.0 (0.315) 1 1,789 (45,434) RLL CS ECMA TC17 5
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0x16 12.7 (0.5) 48 394 (10,000) MFM C X3.193-1990 1
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0x17 12.7 (0.5) 48 1,673 (42,500) MFM C X3B5/91-174 1
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0x18 12.7 (0.5) 112 1,673 (42,500) MFM C X3B5/92-50 1
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0x19 12.7 (0.5) 128 2,460 (62,500) RLL C DLTapeIII 6,7
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0x1A 12.7 (0.5) 128 3,214 (81,633) RLL C DLTapeIV(20) 6,7
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0x1B 12.7 (0.5) 208 3,383 (85,937) RLL C DLTapeIV(35) 6,7
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0x1C 6.3 (0.25) 34 1,654 (42,000) MFM C QIC-385M 1,6
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0x1D 6.3 (0.25) 32 1,512 (38,400) GCR C QIC-410M 1,6
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0x1E 6.3 (0.25) 30 1,385 (36,000) GCR C QIC-1000C 1,6
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0x1F 6.3 (0.25) 30 2,666 (67,733) RLL C QIC-2100C 1,6
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0x20 6.3 (0.25) 144 2,666 (67,733) RLL C QIC-6GB(M) 1,6
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0x21 6.3 (0.25) 144 2,666 (67,733) RLL C QIC-20GB(C) 1,6
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0x22 6.3 (0.25) 42 1,600 (40,640) GCR C QIC-2GB(C) ?
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0x23 6.3 (0.25) 38 2,666 (67,733) RLL C QIC-875M ?
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0x24 3.81 (0.15) 1 2,400 (61,000) CS DDS-2 5
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0x25 3.81 (0.15) 1 3,816 (97,000) CS DDS-3 5
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0x26 3.81 (0.15) 1 3,816 (97,000) CS DDS-4 5
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0x27 8.0 (0.315) 1 3,056 (77,611) RLL CS Mammoth 5
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0x28 12.7 (0.5) 36 1,491 (37,871) GCR C X3.224 1
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0x29 12.7 (0.5)
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0x2A
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0x2B 12.7 (0.5) 3 ? ? ? C X3.267 5
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0x41 12.7 (0.5) 208 3,868 (98,250) RLL C DLTapeIV(40) 6,7
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0x48 12.7 (0.5) 448 5,236 (133,000) PRML C SDLTapeI(110) 6,8
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0x49 12.7 (0.5) 448 7,598 (193,000) PRML C SDLTapeI(160) 6,8
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.Ed
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.Bd -literal -offset 3n
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Code Description Type Description
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---- -------------------------------------- ---- -----------
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NRZI Non return to zero, change on ones R Reel-to-reel
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GCR Group code recording C Cartridge
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PE Phase encoded CS Cassette
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IMFM Inverted modified frequency modulation
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MFM Modified frequency modulation
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DDS DAT data storage
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RLL Run length limited
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PRML Partial Response Maximum Likelihood
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.Ed
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.Bd -literal -offset 3n
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NOTES
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1. Serial recorded.
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2. Parallel recorded.
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3. Old format known as QIC-11.
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5. Helical scan.
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6. This is not an American National Standard. The reference is based on
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an industry standard definition of the media format.
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7. DLT recording: serially recorded track pairs (DLTapeIII and
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DLTapeIV(20)), or track quads (DLTapeIV(35) and DLTapeIV(40)).
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8. Super DLT (SDLT) recording: 56 serially recorded logical tracks with
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8 physical tracks each.
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.Ed
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.Sh ENVIRONMENT
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.Bl -tag -width ".Ev TAPE"
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.It Ev TAPE
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This is the pathname of the tape drive.
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The default (if the variable is unset, but not if it is null) is
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.Pa /dev/nsa0 .
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It may be overridden with the
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.Fl f
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option.
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.El
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.Sh FILES
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.Bl -tag -width ".Pa /dev/*sa[0-9]*" -compact
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.It Pa /dev/*wt*
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QIC-02/QIC-36 magnetic tape interface
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.It Pa /dev/*sa[0-9]*
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SCSI magnetic tape interface
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.El
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.Sh DIAGNOSTICS
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The exit status will be 0 when the drive operations were successful,
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2 when the drive operations were unsuccessful, and 1 for other
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problems like an unrecognized command or a missing drive device.
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.Sh COMPATIBILITY
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Some undocumented commands support old software.
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.Sh SEE ALSO
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.Xr dd 1 ,
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.Xr ioctl 2 ,
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.Xr ast 4 ,
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.Xr mtio 4 ,
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.Xr sa 4 ,
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.Xr environ 7
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.Sh HISTORY
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The
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.Nm
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command appeared in
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.Bx 4.3 .
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.Pp
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Extensions regarding the
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.Xr st 4
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driver appeared in
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.Bx 386 0.1
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as a separate
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.Nm st
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command, and have been merged into the
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.Nm
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command in
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.Fx 2.1 .
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.Pp
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The former
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.Cm eof
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command that used to be a synonym for
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.Cm weof
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has been abandoned in
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.Fx 2.1
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since it was often confused with
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.Cm eom ,
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which is fairly dangerous.
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.Sh BUGS
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The utility cannot be interrupted or killed during a long erase
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(which can be longer than an hour), and it is easy to forget
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that the default erase is long.
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.Pp
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Hardware block numbers do not always correspond to blocks on the tape
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when the drive uses internal compression.
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.Pp
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Erasure is not guaranteed if the tape is not at its beginning.
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.Pp
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Tape-related documentation is poor, here and elsewhere.
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