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29 .\" @(#)mt.1 8.1 (Berkeley) 6/6/93
30 .\" $FreeBSD: src/usr.bin/mt/mt.1,v 1.19.2.8 2002/11/08 11:35:57 joerg Exp $
31 .\"
32 .Dd June 6, 1993
33 .Dt MT 1
34 .Os
35 .Sh NAME
36 .Nm mt
37 .Nd magnetic tape manipulating program
38 .Sh SYNOPSIS
39 .Nm
40 .Op Fl f Ar tapename
41 .Ar command
42 .Op Ar count
43 .Sh DESCRIPTION
44 The
45 .Nm
46 utility is used to give commands to a magnetic tape drive.
47 By default
48 .Nm
49 performs the requested operation once. Operations
50 may be performed multiple times by specifying
51 .Ar count .
52 Note
53 that
54 .Ar tapename
55 must reference a raw (not block) tape device.
56 .Pp
57 The available commands are listed below. Only as many
58 characters as are required to uniquely identify a command
59 need be specified.
60 .Bl -tag -width "eof, weof"
61 .It Cm weof
62 Write
63 .Ar count
64 end-of-file marks at the current position on the tape.
65 .It Cm smk
66 Write
67 .Ar count
68 setmarks at the current position on the tape.
69 .It Cm fsf
70 Forward space
71 .Ar count
72 files.
73 .It Cm fsr
74 Forward space
75 .Ar count
76 records.
77 .It Cm fss
78 Forward space
79 .Ar count
80 setmarks.
81 .It Cm bsf
82 Backward space
83 .Ar count
84 files.
85 .It Cm bsr
86 Backward space
87 .Ar count
88 records.
89 .It Cm bss
90 Backward space
91 .Ar count
92 setmarks.
93 .It Cm rdhpos
94 Read Hardware block position.
95 Some drives do not support this.
96 The block
97 number reported is specific for that hardware only.
98 The count argument is
99 ignored.
100 .It Cm rdspos
101 Read SCSI logical block position.
102 Some drives do not support this.
103 The
104 count argument is ignored.
105 .It Cm sethpos
106 Set Hardware block position.
107 Some drives do not support this.
108 The count
109 argument is interpreted as a hardware block to which to position the tape.
110 .It Cm setspos
111 Set SCSI logical block position.
112 Some drives do not support this.
113 The count
114 argument is interpreted as a SCSI logical block to which to position the tape.
115 .It Cm rewind
116 Rewind the tape
117 (Count is ignored).
118 .It Cm offline , rewoffl
119 Rewind the tape and place the tape unit off-line
120 (Count is ignored).
121 .It Cm erase
122 Erase the tape.
123 A count of 0 disables long erase, which is on by default.
124 .It Cm retension
125 Re-tension the tape
126 (one full wind forth and back, Count is ignored).
127 .It Cm status
128 Print status information about the tape unit.
129 For SCSI magnetic tape devices,
130 the current operating modes of density, blocksize, and whether compression
131 is enabled is reported.
132 The current state of the driver (what it thinks that
133 it is doing with the device) is reported.
134 If the driver knows the relative
135 position from BOT (in terms of filemarks and records), it prints that.
136 Note
137 that this information is not definitive (only BOT, End of Recorded Media, and
138 hardware or SCSI logical block position (if the drive supports such) are
139 considered definitive tape positions).
140 .It Cm errstat
141 Print (and clear) error status information about this device.
142 For every normal
143 operation (e.g., a read or a write) and every control operation (e.g,, a
144 rewind), the driver stores up the last command executed and it's associated
145 status and any residual counts (if any). This command retrieves and prints this
146 information.
147 If possible, this also clears any latched error information.
148 .It Cm blocksize
149 Set the block size for the tape unit. Zero means variable-length
150 blocks.
151 .It Cm density
152 Set the density for the tape unit. For the density codes, see below.
153 The density value could be given either numerically, or as a string,
154 corresponding to the
155 .Dq Reference
156 field. If the string is abbreviated, it will be resolved in the order
157 shown in the table, and the first matching entry will be used. If the
158 given string and the resulting canonical density name do not match
159 exactly, an informational message is printed about what the given
160 string has been taken for.
161 .It Cm geteotmodel
162 Fetch and print out the current EOT filemark model.
163 The model states how
164 many filemarks will be written at close if a tape was being written.
165 .It Cm seteotmodel
166 Set (from the
167 .Ar count
168 argument)
169 and print out the current and EOT filemark model.
170 Typically this will be
171 .Ar 2
172 filemarks, but some devices (typically QIC cartridge drives) can
173 only write
174 .Ar 1
175 filemark.
176 Currently you can only choose a value of
177 .Ar 1
178 or
179 .Ar 2 .
180 .It Cm eom
181 Forward space to end of recorded medium
182 (Count is ignored).
183 .It Cm eod
184 Forward space to end of data, identical to
185 .Cm eom .
186 .It Cm comp
187 Set compression mode.
188 There are currently several possible values for the compression mode:
189 .Pp
190 .Bl -tag -width 9n -compact
191 .It off
192 Turn compression off.
193 .It on
194 Turn compression on.
195 .It none
196 Same as
197 .Ar off .
198 .It enable
199 Same as
200 .Ar on .
201 .It IDRC
202 IBM Improved Data Recording Capability compression (0x10).
203 .It DCLZ
204 DCLZ compression algorithm (0x20).
205 .El
206 .Pp
207 In addition to the above recognized compression keywords, the user can
208 supply a numeric compression algorithm for the tape drive to use. In most
209 cases, simply turning the compression
210 .Sq on
211 will have the desired effect of enabling the default compression algorithm
212 supported by the drive. If this is not the case (see the
213 .Cm status
214 display to see which compression algorithm is currently in use), the user
215 can manually specify one of the supported compression keywords (above), or
216 supply a numeric compression value.
217 .El
218 .Pp
219 If a tape name is not specified, and the environment variable
220 .Ev TAPE
221 does not exist;
222 .Nm
223 uses the device
224 .Pa /dev/nsa0 .
225 .Pp
226 The
227 .Nm
228 utility returns a 0 exit status when the operation(s) were successful,
229 1 if the command was unrecognized, and 2 if an operation failed.
230 .Pp
231 The following density table was taken from the
232 .Sq Historical sequential access density codes
233 table (A-1) in Revision 11 of the SCSI-3 Stream Device Commands (SSC)
234 working draft, dated November 11, 1997.
235 .Pp
236 The different density codes are as follows:
237 .Pp
238 .Dl "0x0 default for device"
239 .Dl "0xE reserved for ECMA"
240 .Bd -literal -offset 3n
241 Value Width Tracks Density Code Type Reference Note
242 mm in bpmm bpi
243 0x01 12.7 (0.5) 9 32 (800) NRZI R X3.22-1983 2
244 0x02 12.7 (0.5) 9 63 (1,600) PE R X3.39-1986 2
245 0x03 12.7 (0.5) 9 246 (6,250) GCR R X3.54-1986 2
246 0x05 6.3 (0.25) 4/9 315 (8,000) GCR C X3.136-1986 1
247 0x06 12.7 (0.5) 9 126 (3,200) PE R X3.157-1987 2
248 0x07 6.3 (0.25) 4 252 (6,400) IMFM C X3.116-1986 1
249 0x08 3.81 (0.15) 4 315 (8,000) GCR CS X3.158-1987 1
250 0x09 12.7 (0.5) 18 1,491 (37,871) GCR C X3.180 2
251 0x0A 12.7 (0.5) 22 262 (6,667) MFM C X3B5/86-199 1
252 0x0B 6.3 (0.25) 4 63 (1,600) PE C X3.56-1986 1
253 0x0C 12.7 (0.5) 24 500 (12,690) GCR C HI-TC1 1,6
254 0x0D 12.7 (0.5) 24 999 (25,380) GCR C HI-TC2 1,6
255 0x0F 6.3 (0.25) 15 394 (10,000) GCR C QIC-120 1,6
256 0x10 6.3 (0.25) 18 394 (10,000) GCR C QIC-150 1,6
257 0x11 6.3 (0.25) 26 630 (16,000) GCR C QIC-320 1,6
258 0x12 6.3 (0.25) 30 2,034 (51,667) RLL C QIC-1350 1,6
259 0x13 3.81 (0.15) 1 2,400 (61,000) DDS CS X3B5/88-185A 5
260 0x14 8.0 (0.315) 1 1,703 (43,245) RLL CS X3.202-1991 5
261 0x15 8.0 (0.315) 1 1,789 (45,434) RLL CS ECMA TC17 5
262 0x16 12.7 (0.5) 48 394 (10,000) MFM C X3.193-1990 1
263 0x17 12.7 (0.5) 48 1,673 (42,500) MFM C X3B5/91-174 1
264 0x18 12.7 (0.5) 112 1,673 (42,500) MFM C X3B5/92-50 1
265 0x19 12.7 (0.5) 128 2,460 (62,500) RLL C DLTapeIII 6,7
266 0x1A 12.7 (0.5) 128 3,214 (81,633) RLL C DLTapeIV(20) 6,7
267 0x1B 12.7 (0.5) 208 3,383 (85,937) RLL C DLTapeIV(35) 6,7
268 0x1C 6.3 (0.25) 34 1,654 (42,000) MFM C QIC-385M 1,6
269 0x1D 6.3 (0.25) 32 1,512 (38,400) GCR C QIC-410M 1,6
270 0x1E 6.3 (0.25) 30 1,385 (36,000) GCR C QIC-1000C 1,6
271 0x1F 6.3 (0.25) 30 2,666 (67,733) RLL C QIC-2100C 1,6
272 0x20 6.3 (0.25) 144 2,666 (67,733) RLL C QIC-6GB(M) 1,6
273 0x21 6.3 (0.25) 144 2,666 (67,733) RLL C QIC-20GB(C) 1,6
274 0x22 6.3 (0.25) 42 1,600 (40,640) GCR C QIC-2GB(C) ?
275 0x23 6.3 (0.25) 38 2,666 (67,733) RLL C QIC-875M ?
276 0x24 3.81 (0.15) 1 2,400 (61,000) CS DDS-2 5
277 0x25 3.81 (0.15) 1 3,816 (97,000) CS DDS-3 5
278 0x26 3.81 (0.15) 1 3,816 (97,000) CS DDS-4 5
279 0x27 8.0 (0.315) 1 3,056 (77,611) RLL CS Mammoth 5
280 0x28 12.7 (0.5) 36 1,491 (37,871) GCR C X3.224 1
281 0x29 12.7 (0.5)
282 0x2A
283 0x2B 12.7 (0.5) 3 ? ? ? C X3.267 5
284 0x41 12.7 (0.5) 208 3,868 (98,250) RLL C DLTapeIV(40) 6,7
285 0x48 12.7 (0.5) 448 5,236 (133,000) PRML C SDLTapeI(110) 6,8
286 0x49 12.7 (0.5) 448 7,598 (193,000) PRML C SDLTapeI(160) 6,8
287 .Ed
288 .Bd -literal -offset 3n
289 Code Description Type Description
290 ---------------- ----------------
291 NRZI Non return to zero, change on ones R Reel-to-reel
292 GCR Group code recording C Cartridge
293 PE Phase encoded CS Cassette
294 IMFM Inverted modified frequency modulation
295 MFM Modified frequency modulation
296 DDS DAT data storage
297 RLL Run length limited
298 PRML Partial Response Maximum Likelihood
299 .Ed
300 .Bd -literal -offset 3n
301 NOTES
302 1. Serial recorded.
303 2. Parallel recorded.
304 3. Old format known as QIC-11.
305 5. Helical scan.
306 6. This is not an American National Standard. The reference is based on
307 an industry standard definition of the media format.
308 7. DLT recording: serially recorded track pairs (DLTapeIII and
309 DLTapeIV(20)), or track quads (DLTapeIV(35) and DLTapeIV(40)).
310 8. Super DLT (SDLT) recording: 56 serially recorded logical tracks with
311 8 physical tracks each.
312 .Ed
313 .Sh ENVIRONMENT
314 If the following environment variable exists, it is utilized by
315 .Nm .
316 .Bl -tag -width Fl
317 .It Ev TAPE
318 The
319 .Nm
320 utility checks the
321 .Ev TAPE
322 environment variable if the
323 argument
324 .Ar tapename
325 is not given.
326 .El
327 .Sh FILES
328 .Bl -tag -width /dev/*rst[0-9]*xx -compact
329 .It Pa /dev/*rsa[0-9]*
330 SCSI magnetic tape interface
331 .El
332 .Sh SEE ALSO
333 .Xr dd 1 ,
334 .Xr ioctl 2 ,
335 .Xr mtio 4 ,
336 .Xr sa 4 ,
337 .Xr environ 7
338 .Sh HISTORY
339 The
340 .Nm
341 command appeared in
342 .Bx 4.3 .
343 .Pp
344 Extensions regarding the
345 .Xr st 4
346 driver appeared in
347 .Bx 386 0.1
348 as a separate
349 .Xr st 1
350 command, and have been merged into the
351 .Nm
352 command in
353 .Fx 2.1 .
354 .Pp
355 The former
356 .Cm eof
357 command that used to be a synonym for
358 .Cm weof
359 has been abandoned in
360 .Fx 2.1
361 since it was often confused with
362 .Cm eom ,
363 which is fairly dangerous.