xref: /freebsd/usr.bin/mt/mt.1 (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
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29.Dd October 31, 2023
30.Dt MT 1
31.Os
32.Sh NAME
33.Nm mt
34.Nd magnetic tape manipulating program
35.Sh SYNOPSIS
36.Nm
37.Op Fl f Ar tapename
38.Ar command
39.Op Ar count
40.Nm
41.Op Fl f Ar tapename
42.Ar command
43.Ar argument
44.Sh DESCRIPTION
45The
46.Nm
47utility is used to command a magnetic tape drive for operations
48other than reading or writing data.
49.Pp
50The
51.Fl f
52option's
53.Ar tapename
54overrides the
55.Ev TAPE
56environment variable described below.
57.Pp
58The available commands are listed below.
59Only as many
60characters as are required to uniquely identify a command
61need be specified.
62.Pp
63The following commands optionally take a
64.Ar count ,
65which defaults to 1.
66.Bl -tag -width ".Cm erase"
67.It Cm weof
68Write
69.Ar count
70end-of-file (EOF) marks at the current position.
71This returns when the file mark has been written to the media.
72.It Cm weofi
73Write
74.Ar count
75end-of-file (EOF) marks at the current position.
76This returns as soon as the command has been validated by the tape drive.
77.It Cm smk
78Write
79.Ar count
80setmarks at the current position (DDS drives only).
81.It Cm fsf
82Forward space
83.Ar count
84files.
85.It Cm fsr
86Forward space
87.Ar count
88records.
89.It Cm fss
90Forward space
91.Ar count
92setmarks (DDS drives only).
93.It Cm bsf
94Backward space
95.Ar count
96files.
97.It Cm bsr
98Backward space
99.Ar count
100records.
101.It Cm bss
102Backward space
103.Ar count
104setmarks (DDS drives only).
105.It Cm erase
106Erase the tape using a long (often very long) method.
107With a
108.Ar count
109of 0, it will erase the tape using a quick method.
110Operation is not guaranteed if the tape is not at its beginning.
111The tape will be at its beginning upon completion.
112.El
113.Pp
114The following commands ignore
115.Ar count .
116.Bl -tag -width ".Cm geteotmodel"
117.It Cm rdhpos
118Read the hardware block position.
119The block
120number reported is specific for that hardware only.
121With drive data compression especially,
122this position may have more to do with the amount of data
123sent to the drive than the amount of data written to tape.
124Some drives do not support this.
125.It Cm rdspos
126Read the SCSI logical block position.
127This typically is greater than the hardware position
128by the number of end-of-file marks.
129Some drives do not support this.
130.It Cm rewind
131Rewind the tape.
132.It Cm offline , rewoffl
133Rewind the tape and place the drive off line.
134Some drives are never off line.
135.It Cm load
136Load the tape into the drive.
137.It Cm retension
138Re-tension the tape.
139This winds the tape from the current position to the end
140and then to the beginning.
141This sometimes improves subsequent reading and writing,
142particularly for streaming drives.
143Some drives do not support this.
144.It Cm ostatus
145Output status information about the drive.
146For SCSI magnetic tape devices,
147the current operating modes of density, blocksize, and whether compression
148is enabled is reported.
149The current state of the driver (what it thinks that
150it is doing with the device) is reported.
151If the driver knows the relative
152position from BOT (in terms of filemarks and records), it outputs that.
153Note
154that this information is not definitive (only BOT, End of Recorded Media, and
155hardware or SCSI logical block position (if the drive supports such) are
156considered definitive tape positions).
157.Pp
158Also note that this is the old status command, and will be eliminated in
159favor of the new status command (see below) in a future release.
160.It Cm errstat
161Output (and clear) error status information about this device.
162For every normal
163operation (e.g., a read or a write) and every control operation (e.g,, a
164rewind), the driver stores up the last command executed and it is associated
165status and any residual counts (if any).
166This command retrieves and outputs this
167information.
168If possible, this also clears any latched error information.
169.It Cm geteotmodel
170Output the current EOT filemark model.
171The model states how
172many filemarks will be written at close if a tape was being written.
173.It Cm eod , eom
174Wind the tape to the end of the recorded data,
175typically after an EOF mark where another file may be written.
176.It Cm rblim
177Report the block limits of the tape drive, including the minimum and
178maximum block size, and the block granularity if any.
179.El
180.Pp
181The following commands may require an
182.Ar argument .
183.Bl -tag -width ".Cm seteotmodel"
184.It Cm sethpos
185Set the hardware block position.
186The
187.Ar argument
188is a hardware block number to which to position the tape.
189Some drives do not support this.
190.It Cm setspos
191Set the SCSI logical block position.
192The
193.Ar argument
194is a SCSI logical block number to which to position the tape.
195Some drives do not support this.
196.It Cm blocksize
197Set the block size for the drive.
198The
199.Ar argument
200is the number of bytes per block,
201except 0 commands the drive to use variable-length blocks.
202.It Cm seteotmodel
203Set the EOT filemark model to
204.Ar argument
205and output the old and new models.
206Typically this will be 2
207filemarks, but some devices (typically QIC cartridge drives) can
208only write 1 filemark.
209You may only choose a value of
210.Ar 1
211or
212.Ar 2 .
213.It Cm status
214Output status information about the drive.
215For SCSI magnetic tape devices,
216the current operating modes of density, blocksize, and whether compression
217is enabled is reported.
218The current state of the driver (what it thinks that
219it is doing with the device) is reported.
220.Pp
221If the driver knows the relative
222position from BOT (in terms of filemarks and records), it outputs that.
223If the tape drive supports the long form report of the
224.Tn SCSI
225READ POSITION command, the Reported File Number and Reported Record Number
226will be numbers other than -1, and there may be Flags reported as well.
227.Pp
228The BOP flag means that the logical position of the drive is at the
229beginning of the partition.
230.Pp
231The EOP flag means that the logical position of the drive is between Early
232Warning and End of Partition.
233.Pp
234The BPEW flag means that the logical position of the drive is in a
235Programmable Early Warning Zone or on the EOP side of Early Warning.
236.Pp
237Note that the Reported Record Number is the tape block or object number
238relative to the beginning of the partition.
239The Calculated Record Number is the tape block or object number relative
240to the previous file mark.
241.Pp
242Note
243that the Calculated File and Record Numbers are not definitive.
244The Reported File and Record Numbers are definitive, if they are numbers
245other than -1.
246.Bl -tag -width 6n
247.It Fl v
248Print additional status information, such as the maximum supported I/O
249size.
250.It Fl x
251Print all available status data to stdout in XML format.
252.El
253.It Cm getdensity
254Report density support information for the tape drive and any media that is
255loaded.
256Most drives will report at least basic density information similar to that
257reported by
258.Nm status
259command.
260Newer tape drives that conform to the T-10 SSC and newer tape
261specifications may report more detailed information about the types of
262tapes they support and the tape currently in the drive.
263.Bl -tag -width 6n
264.It Fl x
265Print all available density data to stdout in XML format.
266Because density information is currently included in the general status XML
267report used for
268.Nm
269status command, this will be the same XML output via
270.Do
271.Nm
272status
273.Fl x
274.Dc
275.El
276.It Cm param
277Display or set parameters.
278One of
279.Fl l ,
280.Fl s ,
281or
282.Fl x
283must be specified to indicate which operation to perform.
284See
285.Xr sa 4
286for more detailed information on the parameters.
287.Bl -tag -width 8n
288.It Fl l
289List parameters, values and descriptions.
290By default all parameters will be displayed.
291To display a specific parameter, specify the parameter with
292.Fl p .
293.It Fl p Ar name
294Specify the parameter name to list (with
295.Fl l )
296or set (with
297.Fl s ) .
298.It Fl q
299Enable quiet mode for parameter listing.
300This will suppress printing of parameter descriptions.
301.It Fl s Ar value
302Specify the parameter value to set.
303The general type of this argument (integer, unsigned integer, string) is
304determined by the type of the variable indicated by the
305.Xr sa 4
306driver.
307More detailed argument checking is done by the
308.Xr sa 4
309driver.
310.It Fl x
311Print out all parameter information in XML format.
312.El
313.It Cm protect
314Display or set drive protection parameters.
315This is used to control checking and reporting a per-block checksum for
316tape drives that support it.
317Some drives may only support some parameters.
318.Bl -tag -width 8n
319.It Fl b Ar 0|1
320Set the Recover Buffered Data Protected bit.
321If set, this indicates that checksums are transferred with the logical
322blocks transferred by the RECOVERED BUFFERED DATA
323.Tn SCSI
324command.
325.It Fl d
326Disable all protection information settings.
327.It Fl e
328Enable all protection information settings.
329The default protection method used is Reed-Solomon CRC (protection method
3301), as specified in ECMA-319.
331The default protection information length used with Reed-Solomon CRC is
3324 bytes.
333To enable all settings except one more setting, specify the
334.Fl e
335argument and then explicitly disable settings that you do not wish to
336enable.
337For example, specifying
338.Fl e
339.Fl w Ar 0
340will enable all settings except for LBP_W.
341.It Fl l
342List available protection parameters and their current settings.
343.It Fl L Ar len
344Set the length of the protection information in bytes.
345For Reed-Solomon CRC, the protection information length should be 4 bytes.
346.It Fl m Ar num
347Specify the numeric value for the protection method.
348The numeric value for Reed-Solomon CRC is 1.
349.It Fl r Ar 0|1
350Set the LBP_R parameter.
351When set, this indicates that each block read from the tape drive will
352have a checksum at the end.
353.It Fl v
354Enable verbose mode for parameter listing.
355This will include descriptions of each parameter.
356.It Fl w Ar 0|1
357Set the LBP_W parameter.
358When set, this indicates that each block written to the tape drive will have
359a checksum at the end.
360The drive will verify the checksum before writing the block to tape.
361.El
362.It Cm locate
363Set the tape drive's logical position.
364One of
365.Fl b ,
366.Fl e ,
367.Fl f ,
368or
369.Fl s
370must be specified to indicate the type of position.
371If the partition number is specified, the drive will first relocate to the
372given partition (if it exists) and then to the position indicated within
373that partition.
374If the partition number is not specified, the drive will relocate to the
375given position within the current partition.
376.Bl -tag -width 14n
377.It Fl b Ar block_addr
378Relocate to the given tape block or logical object identifier.
379Note that the block number is the Reported Record Number that is relative
380to the beginning of the partition (or beginning of tape).
381.It Fl e
382Relocate to the end of data.
383.It Fl f Ar fileno
384Relocate to the given file number.
385.It Fl p Ar partition
386Specify the partition to change to.
387.It Fl s Ar setmark
388Relocate to the given set mark.
389.El
390.It Cm comp
391Set the drive's compression mode.
392The non-numeric values of
393.Ar argument
394are:
395.Pp
396.Bl -tag -width 9n -compact
397.It off
398Turn compression off.
399.It on
400Turn compression on.
401.It none
402Same as
403.Ar off .
404.It enable
405Same as
406.Ar on .
407.It IDRC
408IBM Improved Data Recording Capability compression (0x10).
409.It DCLZ
410DCLZ compression algorithm (0x20).
411.El
412.Pp
413In addition to the above recognized compression keywords, the user can
414supply a numeric compression algorithm for the drive to use.
415In most
416cases, simply turning the compression
417.Sq on
418will have the desired effect of enabling the default compression algorithm
419supported by the drive.
420If this is not the case (see the
421.Cm status
422display to see which compression algorithm is currently in use), the user
423can manually specify one of the supported compression keywords (above), or
424supply a numeric compression value from the drive's specifications.
425.Pp
426Note that for some older tape drives (for example the Exabyte 8200 and 8500
427series drives) it is necessary to switch to a different density to tell the
428drive to record data in its compressed format.
429If the user attempts to turn compression on while the uncompressed density
430is selected, the drive will return an error.
431This is generally not an issue for modern tape drives.
432.It Cm density
433Set the density for the drive.
434For the density codes, see below.
435The density value could be given either numerically, or as a string,
436corresponding to the
437.Dq Reference
438field.
439If the string is abbreviated, it will be resolved in the order
440shown in the table, and the first matching entry will be used.
441If the
442given string and the resulting canonical density name do not match
443exactly, an informational message is output about what the given
444string has been taken for.
445.El
446.Pp
447The initial version of the density table below was taken from the
448.Sq Historical sequential access density codes
449table (A-1) in Revision 11 of the SCSI-3 Stream Device Commands (SSC)
450working draft, dated November 11, 1997.
451Subsequent additions have come from a number of sources.
452.Pp
453The density codes are:
454.Bd -literal -offset 2n
4550x0    default for device
4560xE    reserved for ECMA
457
458Value  Width        Tracks    Density         Code Type Reference   Note
459        mm    in              bpmm       bpi
4600x01   12.7  (0.5)    9         32     (800)  NRZI  R   X3.22-1983   2
4610x02   12.7  (0.5)    9         63   (1,600)  PE    R   X3.39-1986   2
4620x03   12.7  (0.5)    9        246   (6,250)  GCR   R   X3.54-1986   2
4630x05    6.3  (0.25)  4/9       315   (8,000)  GCR   C   X3.136-1986  1,3
4640x06   12.7  (0.5)    9        126   (3,200)  PE    R   X3.157-1987  2
4650x07    6.3  (0.25)   4        252   (6,400)  IMFM  C   X3.116-1986  1
4660x08    3.81 (0.15)   4        315   (8,000)  GCR   CS  X3.158-1987  1
4670x09   12.7  (0.5)   18      1,491  (37,871)  GCR   C   X3.180       2
4680x0A   12.7  (0.5)   22        262   (6,667)  MFM   C   X3B5/86-199  1
4690x0B    6.3  (0.25)   4         63   (1,600)  PE    C   X3.56-1986   1
4700x0C   12.7  (0.5)   24        500  (12,690)  GCR   C   HI-TC1       1,6
4710x0D   12.7  (0.5)   24        999  (25,380)  GCR   C   HI-TC2       1,6
4720x0F    6.3  (0.25)  15        394  (10,000)  GCR   C   QIC-120      1,6
4730x10    6.3  (0.25)  18        394  (10,000)  GCR   C   QIC-150      1,6
4740x11    6.3  (0.25)  26        630  (16,000)  GCR   C   QIC-320      1,6
4750x12    6.3  (0.25)  30      2,034  (51,667)  RLL   C   QIC-1350     1,6
4760x13    3.81 (0.15)   1      2,400  (61,000)  DDS   CS  X3B5/88-185A 5
4770x14    8.0  (0.315)  1      1,703  (43,245)  RLL   CS  X3.202-1991  5,11
4780x15    8.0  (0.315)  1      1,789  (45,434)  RLL   CS  ECMA TC17    5,12
4790x16   12.7  (0.5)   48        394  (10,000)  MFM   C   X3.193-1990  1
4800x17   12.7  (0.5)   48      1,673  (42,500)  MFM   C   X3B5/91-174  1
4810x18   12.7  (0.5)  112      1,673  (42,500)  MFM   C   X3B5/92-50   1
4820x19   12.7  (0.5)  128      2,460  (62,500)  RLL   C   DLTapeIII    6,7
4830x1A   12.7  (0.5)  128      3,214  (81,633)  RLL   C   DLTapeIV(20) 6,7
4840x1B   12.7  (0.5)  208      3,383  (85,937)  RLL   C   DLTapeIV(35) 6,7
4850x1C    6.3  (0.25)  34      1,654  (42,000)  MFM   C   QIC-385M     1,6
4860x1D    6.3  (0.25)  32      1,512  (38,400)  GCR   C   QIC-410M     1,6
4870x1E    6.3  (0.25)  30      1,385  (36,000)  GCR   C   QIC-1000C    1,6
4880x1F    6.3  (0.25)  30      2,666  (67,733)  RLL   C   QIC-2100C    1,6
4890x20    6.3  (0.25) 144      2,666  (67,733)  RLL   C   QIC-6GB(M)   1,6
4900x21    6.3  (0.25) 144      2,666  (67,733)  RLL   C   QIC-20GB(C)  1,6
4910x22    6.3  (0.25)  42      1,600  (40,640)  GCR   C   QIC-2GB(C)   ?
4920x23    6.3  (0.25)  38      2,666  (67,733)  RLL   C   QIC-875M     ?
4930x24    3.81 (0.15)   1      2,400  (61,000)        CS  DDS-2        5
4940x25    3.81 (0.15)   1      3,816  (97,000)        CS  DDS-3        5
4950x26    3.81 (0.15)   1      3,816  (97,000)        CS  DDS-4        5
4960x27    8.0  (0.315)  1      3,056  (77,611)  RLL   CS  Mammoth      5
4970x28   12.7  (0.5)   36      1,491  (37,871)  GCR   C   X3.224       1
4980x29   12.7  (0.5)
4990x2A
5000x2B   12.7  (0.5)    3          ?        ?     ?   C   X3.267       5
5010x40   12.7  (0.5)  384      4,800  (123,952)       C   LTO-1
5020x41   12.7  (0.5)  208      3,868  (98,250)  RLL   C   DLTapeIV(40) 6,7
5030x42   12.7  (0.5)  512      7,398  (187,909)       C   LTO-2
5040x44   12.7  (0.5)  704      9,638  (244,805)       C   LTO-3
5050x46   12.7  (0.5)  896      12,725 (323,215)       C   LTO-4
5060x47    3.81 (0.25)   ?      6,417  (163,000)       CS  DAT-72
5070x48   12.7  (0.5)  448      5,236  (133,000) PRML  C   SDLTapeI(110) 6,8,13
5080x49   12.7  (0.5)  448      7,598  (193,000) PRML  C   SDLTapeI(160) 6,8
5090x4A   12.7  (0.5)  768          ?            PRML  C   T10000A      10
5100x4B   12.7  (0.5) 1152          ?            PRML  C   T10000B      10
5110x4C   12.7  (0.5) 3584          ?            PRML  C   T10000C      10
5120x4D   12.7  (0.5) 4608          ?            PRML  C   T10000D      10
5130x51   12.7  (0.5)  512      11,800 (299,720)       C   3592A1 (unencrypted)
5140x52   12.7  (0.5)  896      11,800 (299,720)       C   3592A2 (unencrypted)
5150x53   12.7  (0.5) 1152      13,452 (341,681)       C   3592A3 (unencrypted)
5160x54   12.7  (0.5) 2560      19,686 (500,024)       C   3592A4 (unencrypted)
5170x55   12.7  (0.5) 5120      20,670 (525,018)       C   3592A5 (unencrypted)
5180x56   12.7  (0.5) 7680      20,670 (525,018)       C   3592B5 (unencrypted)
5190x57   12.7  (0.5) 8704      21,850 (554,990)       C   3592A6 (unencrypted)
5200x58   12.7  (0.5) 1280      15,142 (384,607)       C   LTO-5
5210x59   12.7  (0.5)18944      21,850 (554,990)       C   3592A7 (unencrypted)
5220x5A   12.7  (0.5) 2176      15,142 (384,607)       C   LTO-6
5230x5C   12.7  (0.5) 3584      19,107 (485,318)       C   LTO-7
5240x5D   12.7  (0.5) 5376      19,107 (485,318)       C   LTO-M8       14
5250x5E   12.7  (0.5) 6656      20,669 (524,993)       C   LTO-8
5260x60   12.7  (0.5) 8960      23,031 (584,987)       C   LTO-9
5270x71   12.7  (0.5)  512      11,800 (299,720)       C   3592A1 (encrypted)
5280x72   12.7  (0.5)  896      11,800 (299,720)       C   3592A2 (encrypted)
5290x73   12.7  (0.5) 1152      13,452 (341,681)       C   3592A3 (encrypted)
5300x74   12.7  (0.5) 2560      19,686 (500,024)       C   3592A4 (encrypted)
5310x75   12.7  (0.5) 5120      20,670 (525,018)       C   3592A5 (encrypted)
5320x76   12.7  (0.5) 7680      20,670 (525,018)       C   3592B5 (encrypted)
5330x77   12.7  (0.5) 8704      21,850 (554,990)       C   3592A6 (encrypted)
5340x79   12.7  (0.5)18944      21,850 (554,990)       C   3592A7 (encrypted)
5350x8c    8.0  (0.315)  1      1,789  (45,434)  RLL   CS  EXB-8500c    5,9
5360x90    8.0  (0.315)  1      1,703  (43,245)  RLL   CS  EXB-8200c    5,9
537.Ed
538.Bd -literal -offset 2n
539Code    Description                                Type Description
540----    --------------------------------------     ---- -----------
541NRZI    Non return to zero, change on ones         R    Reel-to-reel
542GCR     Group code recording                       C    Cartridge
543PE      Phase encoded                              CS   Cassette
544IMFM    Inverted modified frequency modulation
545MFM     Modified frequency modulation
546DDS     DAT data storage
547RLL     Run length limited
548PRML    Partial Response Maximum Likelihood
549.Ed
550.Bd -literal -offset 2n
551NOTES
5521.  Serial recorded.
5532.  Parallel recorded.
5543.  Old format known as QIC-11.
5555.  Helical scan.
5566.  This is not an American National Standard.  The reference is based
557    on an industry standard definition of the media format.
5587.  DLT recording: serially recorded track pairs (DLTapeIII and
559    DLTapeIV(20)), or track quads (DLTapeIV(35) and DLTapeIV(40)).
5608.  Super DLT (SDLT) recording: 56 serially recorded logical tracks
561    with 8 physical tracks each.
5629.  Vendor-specific Exabyte density code for compressed format.
56310. bpi/bpmm values for the Oracle/StorageTek T10000 tape drives are
564    not listed in the manual.  Someone with access to a drive can
565    supply the necessary values by running 'mt getdensity'.
56611. This is Exabyte 8200 uncompressed format.  The compressed format
567    density code is 0x90.
56812. This is Exabyte 8500 uncompressed format.  The compressed format
569    density code is 0x8c.
57013. This density code (0x48) was also used for DAT-160.
57114. Officially known as LTO-8 Type M, abbreviated M8.  This is a pristine
572    LTO-7 cartridge initialized with a higher density format by an LTO-8
573    drive.  It cannot be read by an LTO-7 drive.  Uncompressed capacity
574    is 9TB, compared to 6TB for LTO-7 and 12TB for LTO-8.
575.Ed
576.Bd -literal -offset 2n
577NOTE ON QIC STREAMERS
578
579The following is a table of Data Cartridge types as used in the 1/4 inch
580tape drives such as the Archive Viper 150, Wangtek 5525ES, and Tandberg
581TDC4220 tape drives:
582
583Value Reference     Format    Cartridge Type  Capacity   Tracks  Length
584----- ---------     ------    --------------  --------   ------  ------
585
5860x05                QIC-11    DC300           15MB       4        300ft
5870x05                QIC-11    DC300XL/P       20MB       4        450ft
5880x05                QIC-11    DC600           27MB       4        600ft
5890x05  X3.136-1986   QIC-24    DC615A          15MB       9        150ft
5900x05  X3.136-1986   QIC-24    DC300XL/P       45MB       9        450ft
5910x05  X3.136-1986   QIC-24    DC600A          60MB       9        600ft
5920x0F  QIC-120       QIC-120   DC600A/DC6150   120MB      15       620ft
5930x10  QIC-150       QIC-150   DC600XTD/DC6150 150MB      18       620ft
5940x10  QIC-150       QIC-150   DC6250          250MB      18     1,020ft
5950x11  QIC-320       QIC-525   DC6320          320MB      26       620ft
5960x11  QIC-320       QIC-525   DC6525          525MB      26     1,020ft
5970x1E  QIC-1000C     QIC-1000  DC9100/DL9135   1.0GB      30       760ft
5980x1E  QIC-1000C     QIC-1000  DC9150          1.2GB      30       950ft
5990x22  QIC-2GB(C)    QIC-2GB   DC9200          2.0GB      42       950ft
6000x22  QIC-2GB(C)    QIC-2GB   DC9250          2.5GB      42     1,200ft
601.Ed
602.Pp
603Notes:
604.Pp
605QIC-24, QIC-120, QIC-150 use fixed blocksize of 512 bytes, QIC-525, QIC-1000
606and QIC-2GB can use blocksize of 1,024 bytes.
607DDS (DAT) drives generally use variable blocks.
608.Pp
609QIC-02 and QIC-36 are interface standards for tape drives.
610The QIC-02 and QIC-36 streamers such as the Wangtek 5250EQ are otherwise
611identical to their SCSI versions (i.e.: Wangtek 5250ES).
612.Pp
613It seems that the 150MB and larger streamers cannot write QIC-24 9 track
614formats, only read them.
615.Pp
616DC600A cartridges marked "10,000ftpi" can only be used as QIC-11, QIC-24,
617and QIC-120 format.
618DC600A cartridges marked 12,500ftpi can be used as both QIC-120 and QIC-150
619format.
620.Pp
621Some manufacturers do not use "DC" on their cartridges.
622Verbatim uses DL, Maxell uses MC, Sony uses QD, Quill uses DQ.
623.Pp
6243M/Imation & Fuji use DC.
625Thus a DL6250, MC-6250, QD6250, DQ6250 are all identical media to a DC6250.
626.Pp
627QIC tape media is not "connected" to the take up reels and will de-spool
628if the tape drive has dust covering the light sensor that looks for the end
629of tape holes in the media.
630.Sh ENVIRONMENT
631.Bl -tag -width ".Ev TAPE"
632.It Ev TAPE
633This is the pathname of the tape drive.
634The default (if the variable is unset, but not if it is null) is
635.Pa /dev/nsa0 .
636It may be overridden with the
637.Fl f
638option.
639.El
640.Sh FILES
641.Bl -tag -width ".Pa /dev/*sa[0-9]*" -compact
642.It Pa /dev/*sa[0-9]*
643SCSI magnetic tape interface
644.El
645.Sh DIAGNOSTICS
646The exit status will be 0 when the drive operations were successful,
6472 when the drive operations were unsuccessful, and 1 for other
648problems like an unrecognized command or a missing drive device.
649.Sh COMPATIBILITY
650Some undocumented commands support old software.
651.Sh SEE ALSO
652.Xr dd 1 ,
653.Xr ioctl 2 ,
654.Xr mtio 4 ,
655.Xr sa 4 ,
656.Xr environ 7
657.Sh HISTORY
658The
659.Nm
660command appeared in
661.Bx 4.3 .
662.Pp
663Extensions regarding the
664.Xr st 4
665driver appeared in
666.Bx 386 0.1
667as a separate
668.Nm st
669command, and have been merged into the
670.Nm
671command in
672.Fx 2.1 .
673.Pp
674The former
675.Cm eof
676command that used to be a synonym for
677.Cm weof
678has been abandoned in
679.Fx 2.1
680since it was often confused with
681.Cm eom ,
682which is fairly dangerous.
683.Sh BUGS
684The utility cannot be interrupted or killed during a long erase
685(which can be longer than an hour), and it is easy to forget
686that the default erase is long.
687.Pp
688Hardware block numbers do not always correspond to blocks on the tape
689when the drive uses internal compression.
690.Pp
691Erasure is not guaranteed if the tape is not at its beginning.
692.Pp
693Tape-related documentation is poor, here and elsewhere.
694