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MT(1)			  BSD General Commands Manual			 MT(1)

NAME
     mt	-- magnetic tape manipulating program

SYNOPSIS
     mt	[-f tapename] command [count]
     mt	[-f tapename] command argument

DESCRIPTION
     The mt utility is used to command a magnetic tape drive for operations
     other than	reading	or writing data.

     The -f option's tapename overrides	the TAPE environment variable de-
     scribed below.

     The available commands are	listed below.  Only as many characters as are
     required to uniquely identify a command need be specified.

     The following commands optionally take a count, which defaults to 1.

     weof   Write count	end-of-file (EOF) marks	at the current position.  This
	    returns when the file mark has been	written	to the media.

     weofi  Write count	end-of-file (EOF) marks	at the current position.  This
	    returns as soon as the command has been validated by the tape
	    drive.

     smk    Write count	setmarks at the	current	position (DDS drives only).

     fsf    Forward space count	files.

     fsr    Forward space count	records.

     fss    Forward space count	setmarks (DDS drives only).

     bsf    Backward space count files.

     bsr    Backward space count records.

     bss    Backward space count setmarks (DDS drives only).

     erase  Erase the tape using a long	(often very long) method.  With	a
	    count of 0,	it will	erase the tape using a quick method.  Opera-
	    tion is not	guaranteed if the tape is not at its beginning.	 The
	    tape will be at its	beginning upon completion.

     The following commands ignore count.

     rdhpos	  Read the hardware block position.  The block number reported
		  is specific for that hardware	only.  With drive data com-
		  pression 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.

     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.

     rewind	  Rewind the tape.

     offline, rewoffl
		  Rewind the tape and place the	drive off line.	 Some drives
		  are never off	line.

     load	  Load the tape	into the drive.

     retension	  Re-tension the tape.	This winds the tape from the current
		  position to the end and then to the beginning.  This some-
		  times	improves subsequent reading and	writing, particularly
		  for streaming	drives.	 Some drives do	not support this.

     ostatus	  Output status	information about the drive.  For SCSI mag-
		  netic	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 hard-
		  ware or SCSI logical block position (if the drive supports
		  such)	are considered definitive tape positions).

		  Also note that this is the old status	command, and will be
		  eliminated in	favor of the new status	command	(see below) in
		  a future release.

     errstat	  Output (and clear) error status information about this de-
		  vice.	 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 re-
		  trieves and outputs this information.	 If possible, this
		  also clears any latched error	information.

     geteotmodel  Output the current EOT filemark model.  The model states how
		  many filemarks will be written at close if a tape was	being
		  written.

     eod, eom	  Wind the tape	to the end of the recorded data, typically af-
		  ter an EOF mark where	another	file may be written.

     rblim	  Report the block limits of the tape drive, including the
		  minimum and maximum block size, and the block	granularity if
		  any.

     The following commands may	require	an argument.

     sethpos	  Set the hardware block position.  The	argument is a hardware
		  block	number to which	to position the	tape.  Some drives do
		  not support this.

     setspos	  Set the SCSI logical block position.	The argument is	a SCSI
		  logical block	number to which	to position the	tape.  Some
		  drives do not	support	this.

     blocksize	  Set the block	size for the drive.  The argument is the num-
		  ber of bytes per block, except 0 commands the	drive to use
		  variable-length blocks.

     seteotmodel  Set the EOT filemark model to	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 1	or 2.

     status	  Output status	information about the drive.  For SCSI mag-
		  netic	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.  If the tape
		  drive	supports the long form report of the SCSI READ POSI-
		  TION command,	the Reported File Number and Reported Record
		  Number will be numbers other than -1,	and there may be Flags
		  reported as well.

		  The BOP flag means that the logical position of the drive is
		  at the beginning of the partition.

		  The EOP flag means that the logical position of the drive is
		  between Early	Warning	and End	of Partition.

		  The BPEW flag	means that the logical position	of the drive
		  is in	a Programmable Early Warning Zone or on	the EOP	side
		  of Early Warning.

		  Note that the	Reported Record	Number is the tape block or
		  object number	relative to the	beginning of the partition.
		  The Calculated Record	Number is the tape block or object
		  number relative to the previous file mark.

		  Note that the	Calculated File	and Record Numbers are not de-
		  finitive.  The Reported File and Record Numbers are defini-
		  tive,	if they	are numbers other than -1.

		  -v	  Print	additional status information, such as the
			  maximum supported I/O	size.

		  -x	  Print	all available status data to stdout in XML
			  format.

     getdensity	  Report density support information for the tape drive	and
		  any media that is loaded.  Most drives will report at	least
		  basic	density	information similar to that reported by	status
		  command.  Newer tape drives that conform to the T-10 SSC and
		  newer	tape specifications may	report more detailed informa-
		  tion about the types of tapes	they support and the tape cur-
		  rently in the	drive.

		  -x	  Print	all available density data to stdout in	XML
			  format.  Because density information is currently
			  included in the general status XML report used for
			  mt status command, this will be the same XML output
			  via "mt status -x"

     param	  Display or set parameters.  One of -l, -s, or	-x must	be
		  specified to indicate	which operation	to perform.  See sa(4)
		  for more detailed information	on the parameters.

		  -l	    List parameters, values and	descriptions.  By de-
			    fault all parameters will be displayed.  To	dis-
			    play a specific parameter, specify the parameter
			    with -p.

		  -p name   Specify the	parameter name to list (with -l) or
			    set	(with -s).

		  -q	    Enable quiet mode for parameter listing.  This
			    will suppress printing of parameter	descriptions.

		  -s value  Specify the	parameter value	to set.	 The general
			    type of this argument (integer, unsigned integer,
			    string) is determined by the type of the variable
			    indicated by the sa(4) driver.  More detailed ar-
			    gument checking is done by the sa(4) driver.

		  -x	    Print out all parameter information	in XML format.

     protect	  Display or set drive protection parameters.  This is used to
		  control checking and reporting a per-block checksum for tape
		  drives that support it.  Some	drives may only	support	some
		  parameters.

		  -b 0|1    Set	the Recover Buffered Data Protected bit.  If
			    set, this indicates	that checksums are transferred
			    with the logical blocks transferred	by the RECOV-
			    ERED BUFFERED DATA SCSI command.

		  -d	    Disable all	protection information settings.

		  -e	    Enable all protection information settings.	 The
			    default protection method used is Reed-Solomon CRC
			    (protection	method 1), as specified	in ECMA-319.
			    The	default	protection information length used
			    with Reed-Solomon CRC is 4 bytes.  To enable all
			    settings except one	more setting, specify the -e
			    argument and then explicitly disable settings that
			    you	do not wish to enable.	For example, specify-
			    ing	-e -w 0	will enable all	settings except	for
			    LBP_W.

		  -l	    List available protection parmeters	and their cur-
			    rent settings.

		  -L len    Set	the length of the protection information in
			    bytes.  For	Reed-Solomon CRC, the protection in-
			    formation length should be 4 bytes.

		  -m num    Specify the	numeric	value for the protection
			    method.  The numeric value for Reed-Solomon	CRC is
			    1.

		  -r 0|1    Set	the LBP_R parameter.  When set,	this indicates
			    that each block read from the tape drive will have
			    a checksum at the end.

		  -v	    Enable verbose mode	for parameter listing.	This
			    will include descriptions of each parameter.

		  -w 0|1    Set	the LBP_W parameter.  When set,	this indicates
			    that each block written to the tape	drive will
			    have a checksum at the end.	 The drive will	verify
			    the	checksum before	writing	the block to tape.

     locate	  Set the tape drive's logical position.  One of -b, -e, -f,
		  or -s	must be	specified to indicate the type of position.
		  If the partition number is specified,	the drive will first
		  relocate to the given	partition (if it exists) and then to
		  the position indicated within	that partition.	 If the	parti-
		  tion number is not specified,	the drive will relocate	to the
		  given	position within	the current partition.

		  -b block_addr	  Relocate to the given	tape block or logical
				  object identifier.  Note that	the block num-
				  ber is the Reported Record Number that is
				  relative to the beginning of the partition
				  (or beginning	of tape).

		  -e		  Relocate to the end of data.

		  -f fileno	  Relocate to the given	file number.

		  -p partition	  Specify the partition	to change to.

		  -s setmark	  Relocate to the given	set mark.

     comp	  Set the drive's compression mode.  The non-numeric values of
		  argument are:

		  off	     Turn compression off.
		  on	     Turn compression on.
		  none	     Same as off.
		  enable     Same as on.
		  IDRC	     IBM Improved Data Recording Capability compres-
			     sion (0x10).
		  DCLZ	     DCLZ compression algorithm	(0x20).

		  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
		  `on' will have the desired effect of enabling	the default
		  compression algorithm	supported by the drive.	 If this is
		  not the case (see the	status display to see which compres-
		  sion 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 spec-
		  ifications.

		  Note that for	some older tape	drives (for example the	Ex-
		  abyte	8200 and 8500 series drives) it	is necessary to	switch
		  to a different density to tell the drive to record data in
		  its compressed format.  If the user attempts to turn com-
		  pression on while the	uncompressed density is	selected, the
		  drive	will return an error.  This is generally not an	issue
		  for modern tape drives.

     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 "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 den-
		  sity name do not match exactly, an informational message is
		  output about what the	given string has been taken for.

     The initial version of the	density	table below was	taken from the
     `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.	Subsequent additions have come from a number of	sources.

     The density codes are:

       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  1,3
       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  5,11
       0x15    8.0  (0.315)  1	    1,789  (45,434)  RLL   CS  ECMA TC17    5,12
       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
       0x40   12.7  (0.5)  384	    4,800  (123,952)	   C   LTO-1
       0x41   12.7  (0.5)  208	    3,868  (98,250)  RLL   C   DLTapeIV(40) 6,7
       0x42   12.7  (0.5)  512	    7,398  (187,909)	   C   LTO-2
       0x44   12.7  (0.5)  704	    9,638  (244,805)	   C   LTO-3
       0x46   12.7  (0.5)  896	    12,725 (323,215)	   C   LTO-4
       0x47    3.81 (0.25)   ?	    6,417  (163,000)	   CS  DAT-72
       0x48   12.7  (0.5)  448	    5,236  (133,000) PRML  C   SDLTapeI(110) 6,8,13
       0x49   12.7  (0.5)  448	    7,598  (193,000) PRML  C   SDLTapeI(160) 6,8
       0x4A   12.7  (0.5)  768		?	     PRML  C   T10000A	    10
       0x4B   12.7  (0.5) 1152		?	     PRML  C   T10000B	    10
       0x4C   12.7  (0.5) 3584		?	     PRML  C   T10000C	    10
       0x4D   12.7  (0.5) 4608		?	     PRML  C   T10000D	    10
       0x51   12.7  (0.5)  512	    11,800 (299,720)	   C   3592A1 (unencrypted)
       0x52   12.7  (0.5)  896	    11,800 (299,720)	   C   3592A2 (unencrypted)
       0x53   12.7  (0.5) 1152	    13,452 (341,681)	   C   3592A3 (unencrypted)
       0x54   12.7  (0.5) 2560	    19,686 (500,024)	   C   3592A4 (unencrypted)
       0x55   12.7  (0.5) 5120	    20,670 (525,018)	   C   3592A5 (unencrypted)
       0x56   12.7  (0.5) 7680	    20,670 (525,018)	   C   3592B5 (unencrypted)
       0x58   12.7  (0.5) 1280	    15,142 (384,607)	   C   LTO-5
       0x5A   12.7  (0.5) 2176	    15,142 (384,607)	   C   LTO-6
       0x5C   12.7  (0.5) 3584	    19,107 (485,318)	   C   LTO-7
       0x5D   12.7  (0.5) 5376	    19,107 (485,318)	   C   LTO-M8	    14
       0x5E   12.7  (0.5) 6656	    20,669 (524,993)	   C   LTO-8
       0x71   12.7  (0.5)  512	    11,800 (299,720)	   C   3592A1 (encrypted)
       0x72   12.7  (0.5)  896	    11,800 (299,720)	   C   3592A2 (encrypted)
       0x73   12.7  (0.5) 1152	    13,452 (341,681)	   C   3592A3 (encrypted)
       0x74   12.7  (0.5) 2560	    19,686 (500,024)	   C   3592A4 (encrypted)
       0x75   12.7  (0.5) 5120	    20,670 (525,018)	   C   3592A5 (encrypted)
       0x76   12.7  (0.5) 7680	    20,670 (525,018)	   C   3592B5 (encrypted)
       0x8c    8.0  (0.315)  1	    1,789  (45,434)  RLL   CS  EXB-8500c    5,9
       0x90    8.0  (0.315)  1	    1,703  (43,245)  RLL   CS  EXB-8200c    5,9

       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

       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.
       9.  Vendor-specific Exabyte density code	for compressed format.
       10. bpi/bpmm values for the Oracle/StorageTek T10000 tape drives	are
	   not listed in the manual.  Someone with access to a drive can
	   supply the necessary	values by running 'mt getdensity'.
       11. This	is Exabyte 8200	uncompressed format.  The compressed format
	   density code	is 0x90.
       12. This	is Exabyte 8500	uncompressed format.  The compressed format
	   density code	is 0x8c.
       13. This	density	code (0x48) was	also used for DAT-160.
       14. Officially known as LTO-8 Type M, abbreviated M8.  This is a	pristine
	   LTO-7 cartridge initialized with a higher density format by an LTO-8
	   drive.  It cannot be	read by	an LTO-7 drive.	 Uncompressed capacity
	   is 9TB, compared to 6TB for LTO-7 and 12TB for LTO-8.

       NOTE ON QIC STREAMERS

       The following is	a table	of Data	Cartridge types	as used	in the 1/4 inch
       tape drives such	as the Archive Viper 150, Wangtek 5525ES, and Tandberg
       TDC4220 tape drives:

       Value Reference	   Format    Cartridge Type  Capacity	Tracks	Length
       ----- ---------	   ------    --------------  --------	------	------

       0x05		   QIC-11    DC300	     15MB	4	 300ft
       0x05		   QIC-11    DC300XL/P	     20MB	4	 450ft
       0x05		   QIC-11    DC600	     27MB	4	 600ft
       0x05  X3.136-1986   QIC-24    DC615A	     15MB	9	 150ft
       0x05  X3.136-1986   QIC-24    DC300XL/P	     45MB	9	 450ft
       0x05  X3.136-1986   QIC-24    DC600A	     60MB	9	 600ft
       0x0F  QIC-120	   QIC-120   DC600A/DC6150   120MB	15	 620ft
       0x10  QIC-150	   QIC-150   DC600XTD/DC6150 150MB	18	 620ft
       0x10  QIC-150	   QIC-150   DC6250	     250MB	18     1,020ft
       0x11  QIC-320	   QIC-525   DC6320	     320MB	26	 620ft
       0x11  QIC-320	   QIC-525   DC6525	     525MB	26     1,020ft
       0x1E  QIC-1000C	   QIC-1000  DC9100/DL9135   1.0GB	30	 760ft
       0x1E  QIC-1000C	   QIC-1000  DC9150	     1.2GB	30	 950ft
       0x22  QIC-2GB(C)	   QIC-2GB   DC9200	     2.0GB	42	 950ft
       0x22  QIC-2GB(C)	   QIC-2GB   DC9250	     2.5GB	42     1,200ft

     Notes:

     QIC-24, QIC-120, QIC-150 use fixed	blocksize of 512 bytes,	QIC-525,
     QIC-1000 and QIC-2GB can use blocksize of 1,024 bytes.  DDS (DAT) drives
     generally use variable blocks.

     QIC-02 and	QIC-36 are interface standards for tape	drives.	 The QIC-02
     and QIC-36	streamers such as the Wangtek 5250EQ are otherwise identical
     to	their SCSI versions (i.e.: Wangtek 5250ES).

     It	seems that the 150MB and larger	streamers cannot write QIC-24 9	track
     formats, only read	them.

     DC600A cartridges marked "10,000ftpi" can only be used as QIC-11, QIC-24,
     and QIC-120 format.  DC600A cartridges marked 12,500ftpi can be used as
     both QIC-120 and QIC-150 format.

     Some manufacturers	do not use "DC"	on their cartridges.  Verbatim uses
     DL, Maxell	uses MC, Sony uses QD, Quill uses DQ.

     3M/Imation	& Fuji use DC.	Thus a DL6250, MC-6250,	QD6250,	DQ6250 are all
     identical media to	a DC6250.

     QIC tape media is not "connected" to the take up reels and	will de-spool
     if	the tape drive has dust	covering the light sensor that looks for the
     end of tape holes in the media.

ENVIRONMENT
     TAPE  This	is the pathname	of the tape drive.  The	default	(if the	vari-
	   able	is unset, but not if it	is null) is /dev/nsa0.	It may be
	   overridden with the -f option.

FILES
     /dev/*sa[0-9]*  SCSI magnetic tape	interface

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.

COMPATIBILITY
     Some undocumented commands	support	old software.

SEE ALSO
     dd(1), ioctl(2), mtio(4), sa(4), environ(7)

HISTORY
     The mt command appeared in	4.3BSD.

     Extensions	regarding the st(4) driver appeared in 386BSD 0.1 as a sepa-
     rate st command, and have been merged into	the mt command in FreeBSD 2.1.

     The former	eof command that used to be a synonym for weof has been	aban-
     doned in FreeBSD 2.1 since	it was often confused with eom,	which is
     fairly dangerous.

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.

     Hardware block numbers do not always correspond to	blocks on the tape
     when the drive uses internal compression.

     Erasure is	not guaranteed if the tape is not at its beginning.

     Tape-related documentation	is poor, here and elsewhere.

BSD			       November	3, 2017				   BSD

NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | FILES | DIAGNOSTICS | COMPATIBILITY | SEE ALSO | HISTORY | BUGS

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