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