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33 .\" @(#)mt.1 8.1 (Berkeley) 6/6/93
34 .\" $FreeBSD: src/usr.bin/mt/mt.1,v 1.19.2.8 2002/11/08 11:35:57 joerg Exp $
35 .\" $DragonFly: src/usr.bin/mt/mt.1,v 1.2 2003/06/17 04:29:29 dillon Exp $
36 .\"
37 .Dd June 6, 1993
38 .Dt MT 1
39 .Os
40 .Sh NAME
41 .Nm mt
42 .Nd magnetic tape manipulating program
43 .Sh SYNOPSIS
44 .Nm
45 .Op Fl f Ar tapename
46 .Ar command
47 .Op Ar count
48 .Sh DESCRIPTION
49 The
50 .Nm
51 utility is used to give commands to a magnetic tape drive.
52 By default
53 .Nm
54 performs the requested operation once. Operations
55 may be performed multiple times by specifying
56 .Ar count .
57 Note
58 that
59 .Ar tapename
60 must reference a raw (not block) tape device.
61 .Pp
62 The available commands are listed below. Only as many
63 characters as are required to uniquely identify a command
64 need be specified.
65 .Bl -tag -width "eof, weof"
66 .It Cm weof
67 Write
68 .Ar count
69 end-of-file marks at the current position on the tape.
70 .It Cm smk
71 Write
72 .Ar count
73 setmarks at the current position on the tape.
74 .It Cm fsf
75 Forward space
76 .Ar count
77 files.
78 .It Cm fsr
79 Forward space
80 .Ar count
81 records.
82 .It Cm fss
83 Forward space
84 .Ar count
85 setmarks.
86 .It Cm bsf
87 Backward space
88 .Ar count
89 files.
90 .It Cm bsr
91 Backward space
92 .Ar count
93 records.
94 .It Cm bss
95 Backward space
96 .Ar count
97 setmarks.
98 .It Cm rdhpos
99 Read Hardware block position.
100 Some drives do not support this.
101 The block
102 number reported is specific for that hardware only.
103 The count argument is
104 ignored.
105 .It Cm rdspos
106 Read SCSI logical block position.
107 Some drives do not support this.
108 The
109 count argument is ignored.
110 .It Cm sethpos
111 Set Hardware block position.
112 Some drives do not support this.
113 The count
114 argument is interpreted as a hardware block to which to position the tape.
115 .It Cm setspos
116 Set SCSI logical block position.
117 Some drives do not support this.
118 The count
119 argument is interpreted as a SCSI logical block to which to position the tape.
120 .It Cm rewind
121 Rewind the tape
122 (Count is ignored).
123 .It Cm offline , rewoffl
124 Rewind the tape and place the tape unit off-line
125 (Count is ignored).
126 .It Cm erase
127 Erase the tape.
128 A count of 0 disables long erase, which is on by default.
129 .It Cm retension
130 Re-tension the tape
131 (one full wind forth and back, Count is ignored).
132 .It Cm status
133 Print status information about the tape unit.
134 For SCSI magnetic tape devices,
135 the current operating modes of density, blocksize, and whether compression
136 is enabled is reported.
137 The current state of the driver (what it thinks that
138 it is doing with the device) is reported.
139 If the driver knows the relative
140 position from BOT (in terms of filemarks and records), it prints that.
141 Note
142 that this information is not definitive (only BOT, End of Recorded Media, and
143 hardware or SCSI logical block position (if the drive supports such) are
144 considered definitive tape positions).
145 .It Cm errstat
146 Print (and clear) error status information about this device.
147 For every normal
148 operation (e.g., a read or a write) and every control operation (e.g,, a
149 rewind), the driver stores up the last command executed and it's associated
150 status and any residual counts (if any). This command retrieves and prints this
151 information.
152 If possible, this also clears any latched error information.
153 .It Cm blocksize
154 Set the block size for the tape unit. Zero means variable-length
155 blocks.
156 .It Cm density
157 Set the density for the tape unit. For the density codes, see below.
158 The density value could be given either numerically, or as a string,
159 corresponding to the
160 .Dq Reference
161 field. If the string is abbreviated, it will be resolved in the order
162 shown in the table, and the first matching entry will be used. If the
163 given string and the resulting canonical density name do not match
164 exactly, an informational message is printed about what the given
165 string has been taken for.
166 .It Cm geteotmodel
167 Fetch and print out the current EOT filemark model.
168 The model states how
169 many filemarks will be written at close if a tape was being written.
170 .It Cm seteotmodel
171 Set (from the
172 .Ar count
173 argument)
174 and print out the current and EOT filemark model.
175 Typically this will be
176 .Ar 2
177 filemarks, but some devices (typically QIC cartridge drives) can
178 only write
179 .Ar 1
180 filemark.
181 Currently you can only choose a value of
182 .Ar 1
183 or
184 .Ar 2 .
185 .It Cm eom
186 Forward space to end of recorded medium
187 (Count is ignored).
188 .It Cm eod
189 Forward space to end of data, identical to
190 .Cm eom .
191 .It Cm comp
192 Set compression mode.
193 There are currently several possible values for the compression mode:
194 .Pp
195 .Bl -tag -width 9n -compact
196 .It off
197 Turn compression off.
198 .It on
199 Turn compression on.
200 .It none
201 Same as
202 .Ar off .
203 .It enable
204 Same as
205 .Ar on .
206 .It IDRC
207 IBM Improved Data Recording Capability compression (0x10).
208 .It DCLZ
209 DCLZ compression algorithm (0x20).
210 .El
211 .Pp
212 In addition to the above recognized compression keywords, the user can
213 supply a numeric compression algorithm for the tape drive to use. In most
214 cases, simply turning the compression
215 .Sq on
216 will have the desired effect of enabling the default compression algorithm
217 supported by the drive. If this is not the case (see the
218 .Cm status
219 display to see which compression algorithm is currently in use), the user
220 can manually specify one of the supported compression keywords (above), or
221 supply a numeric compression value.
222 .El
223 .Pp
224 If a tape name is not specified, and the environment variable
225 .Ev TAPE
226 does not exist;
227 .Nm
228 uses the device
229 .Pa /dev/nsa0 .
230 .Pp
231 The
232 .Nm
233 utility returns a 0 exit status when the operation(s) were successful,
234 1 if the command was unrecognized, and 2 if an operation failed.
235 .Pp
236 The following density table was taken from the
237 .Sq Historical sequential access density codes
238 table (A-1) in Revision 11 of the SCSI-3 Stream Device Commands (SSC)
239 working draft, dated November 11, 1997.
240 .Pp
241 The different density codes are as follows:
242 .Pp
243 .Dl "0x0 default for device
244 .Dl "0xE reserved for ECMA
245 .Bd -literal -offset 3n
246 Value Width Tracks Density Code Type Reference Note
247 mm in bpmm bpi
248 0x01 12.7 (0.5) 9 32 (800) NRZI R X3.22-1983 2
249 0x02 12.7 (0.5) 9 63 (1,600) PE R X3.39-1986 2
250 0x03 12.7 (0.5) 9 246 (6,250) GCR R X3.54-1986 2
251 0x05 6.3 (0.25) 4/9 315 (8,000) GCR C X3.136-1986 1
252 0x06 12.7 (0.5) 9 126 (3,200) PE R X3.157-1987 2
253 0x07 6.3 (0.25) 4 252 (6,400) IMFM C X3.116-1986 1
254 0x08 3.81 (0.15) 4 315 (8,000) GCR CS X3.158-1987 1
255 0x09 12.7 (0.5) 18 1,491 (37,871) GCR C X3.180 2
256 0x0A 12.7 (0.5) 22 262 (6,667) MFM C X3B5/86-199 1
257 0x0B 6.3 (0.25) 4 63 (1,600) PE C X3.56-1986 1
258 0x0C 12.7 (0.5) 24 500 (12,690) GCR C HI-TC1 1,6
259 0x0D 12.7 (0.5) 24 999 (25,380) GCR C HI-TC2 1,6
260 0x0F 6.3 (0.25) 15 394 (10,000) GCR C QIC-120 1,6
261 0x10 6.3 (0.25) 18 394 (10,000) GCR C QIC-150 1,6
262 0x11 6.3 (0.25) 26 630 (16,000) GCR C QIC-320 1,6
263 0x12 6.3 (0.25) 30 2,034 (51,667) RLL C QIC-1350 1,6
264 0x13 3.81 (0.15) 1 2,400 (61,000) DDS CS X3B5/88-185A 5
265 0x14 8.0 (0.315) 1 1,703 (43,245) RLL CS X3.202-1991 5
266 0x15 8.0 (0.315) 1 1,789 (45,434) RLL CS ECMA TC17 5
267 0x16 12.7 (0.5) 48 394 (10,000) MFM C X3.193-1990 1
268 0x17 12.7 (0.5) 48 1,673 (42,500) MFM C X3B5/91-174 1
269 0x18 12.7 (0.5) 112 1,673 (42,500) MFM C X3B5/92-50 1
270 0x19 12.7 (0.5) 128 2,460 (62,500) RLL C DLTapeIII 6,7
271 0x1A 12.7 (0.5) 128 3,214 (81,633) RLL C DLTapeIV(20) 6,7
272 0x1B 12.7 (0.5) 208 3,383 (85,937) RLL C DLTapeIV(35) 6,7
273 0x1C 6.3 (0.25) 34 1,654 (42,000) MFM C QIC-385M 1,6
274 0x1D 6.3 (0.25) 32 1,512 (38,400) GCR C QIC-410M 1,6
275 0x1E 6.3 (0.25) 30 1,385 (36,000) GCR C QIC-1000C 1,6
276 0x1F 6.3 (0.25) 30 2,666 (67,733) RLL C QIC-2100C 1,6
277 0x20 6.3 (0.25) 144 2,666 (67,733) RLL C QIC-6GB(M) 1,6
278 0x21 6.3 (0.25) 144 2,666 (67,733) RLL C QIC-20GB(C) 1,6
279 0x22 6.3 (0.25) 42 1,600 (40,640) GCR C QIC-2GB(C) ?
280 0x23 6.3 (0.25) 38 2,666 (67,733) RLL C QIC-875M ?
281 0x24 3.81 (0.15) 1 2,400 (61,000) CS DDS-2 5
282 0x25 3.81 (0.15) 1 3,816 (97,000) CS DDS-3 5
283 0x26 3.81 (0.15) 1 3,816 (97,000) CS DDS-4 5
284 0x27 8.0 (0.315) 1 3,056 (77,611) RLL CS Mammoth 5
285 0x28 12.7 (0.5) 36 1,491 (37,871) GCR C X3.224 1
286 0x29 12.7 (0.5)
287 0x2A
288 0x2B 12.7 (0.5) 3 ? ? ? C X3.267 5
289 0x41 12.7 (0.5) 208 3,868 (98,250) RLL C DLTapeIV(40) 6,7
290 0x48 12.7 (0.5) 448 5,236 (133,000) PRML C SDLTapeI(110) 6,8
291 0x49 12.7 (0.5) 448 7,598 (193,000) PRML C SDLTapeI(160) 6,8
292 .Ed
293 .Bd -literal -offset 3n
294 Code Description Type Description
295 ---------------- ----------------
296 NRZI Non return to zero, change on ones R Reel-to-reel
297 GCR Group code recording C Cartridge
298 PE Phase encoded CS Cassette
299 IMFM Inverted modified frequency modulation
300 MFM Modified frequency modulation
301 DDS DAT data storage
302 RLL Run length limited
303 PRML Partial Response Maximum Likelihood
304 .Ed
305 .Bd -literal -offset 3n
306 NOTES
307 1. Serial recorded.
308 2. Parallel recorded.
309 3. Old format known as QIC-11.
310 5. Helical scan.
311 6. This is not an American National Standard. The reference is based on
312 an industry standard definition of the media format.
313 7. DLT recording: serially recorded track pairs (DLTapeIII and
314 DLTapeIV(20)), or track quads (DLTapeIV(35) and DLTapeIV(40)).
315 8. Super DLT (SDLT) recording: 56 serially recorded logical tracks with
316 8 physical tracks each.
317 .Ed
318 .Sh ENVIRONMENT
319 If the following environment variable exists, it is utilized by
320 .Nm .
321 .Bl -tag -width Fl
322 .It Ev TAPE
323 The
324 .Nm
325 utility checks the
326 .Ev TAPE
327 environment variable if the
328 argument
329 .Ar tapename
330 is not given.
331 .El
332 .Sh FILES
333 .Bl -tag -width /dev/*rst[0-9]*xx -compact
334 .It Pa /dev/*rwt*
335 QIC-02/QIC-36 magnetic tape interface
336 .It Pa /dev/*rsa[0-9]*
337 SCSI magnetic tape interface
338 .El
339 .Sh SEE ALSO
340 .Xr dd 1 ,
341 .Xr ioctl 2 ,
342 .Xr mtio 4 ,
343 .Xr sa 4 ,
344 .Xr wt 4 ,
345 .Xr environ 7
346 .Sh HISTORY
347 The
348 .Nm
349 command appeared in
350 .Bx 4.3 .
351 .Pp
352 Extensions regarding the
353 .Xr st 4
354 driver appeared in
355 .Bx 386 0.1
356 as a separate
357 .Xr st 1
358 command, and have been merged into the
359 .Nm
360 command in
361 .Fx 2.1 .
362 .Pp
363 The former
364 .Cm eof
365 command that used to be a synonym for
366 .Cm weof
367 has been abandoned in
368 .Fx 2.1
369 since it was often confused with
370 .Cm eom ,
371 which is fairly dangerous.