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 mt(7)								       mt(7)




 NAME
      mt - magnetic tape interface and controls for stape and tape2

 DESCRIPTION
      This entry describes the behavior of HP magnetic tape interfaces and
      controls, including reel-to-reel, DDS, QIC, 8mm, and 3480 tape drives.
      The files /dev/rmt/* refer to specific raw tape drives, and the
      behavior of each given unit is specified in the major and minor
      numbers of the device special file.

    Naming Conventions
      There are two naming conventions for device special files.  The
      standard (preferred) convention is used on systems that support long
      file names.  An alternate convention is provided for systems limited
      to short file names.  The following standard convention is recommended
      because it allows for all possible configuration options in the device
      name and is used by mksf(1M) and insf(1M):

	   /dev/rmt/c#t#d#[o][z][e][p][s[#]][w]density[C[#]][n][b]

      The following alternate naming convention is provided to support
      systems in which the /dev/rmt directory requires short file names.
      These device special file names are less descriptive, but guarantee
      unique device naming and are used by mksf(1M) and insf(1M) where
      required.

	   /dev/rmt/c#t#d#[f#|i#][n][b]

      For each tape device present, eight device files are automatically
      created when the system is initialized.  Four of these device files
      utilize either the standard (long file name) or alternate (short file
      name) naming conventions.	 When the standard naming convention is
      being utilized, these four files contain the density specification
      "BEST".  When the alternate naming convention is being utilized, these
      four files contain the density specification "f0".  There are four
      such files because each of the four different permutations of the "n"
      and "b" options (see below) is available.

      The remaining four files automatically created when the system is
      initialized utilize the pre-HP-UX 10.0 device file naming convention.
      This includes an arbitrary number to distinguish this tape device from
      others in the system, followed by the letter m.  There are four such
      files because each of the four different permutations of the n and b
      options (see below) is available.	 These files are created as a
      usability feature for pre-HP-UX 10.0 users who do not wish to acquire
      familiarity with the standard or alternate naming conventions.

      Each of the automatically created four device files which utilize the
      standard or alternate naming conventions is linked to a device file
      which utilizes the pre-HP-UX 10.0 naming convention.  Thus, the device
      files which utilize the pre-HP-UX 10.0 naming convention provide the



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      same functionality as the device files which contain the density
      specification BEST (standard naming convention) or f0 (alternate
      naming convention).

    Options
      The options described here are common to all tape drivers.  The c#t#d#
      notation in the device special file name derives from ioscan output
      and is described on the manpages for ioscan(1M) and intro(7).  Options
      unique to stape and tape2 are described later in this manpage, in the
      DEPENDENCIES section.

      c#	Instance number assigned by the operating system to the
		interface card.

      t#	Target address on a remote bus (for example, SCSI address)

      d#	Device unit number at the target address (for example, SCSI
		LUN).

      w		Writes wait for physical completion of the operation before
		returning status.  The default behavior (buffered mode or
		immediate reporting mode) requires the tape device to buffer
		the data and return immediately with successful status.

      density	Density or format used in writing data to tape.	 This field
		is designated by the following values:

		BEST	       Highest-capacity density or format will be
			       used, including data compression, if the
			       device supports compression.

		NOMOD	       Maintains the density used for data
			       previously written to the tape.	Behavior
			       using this option is dependent on the type of
			       device.	This option is only supported on DDS
			       and 8MM drives.

		DDS	       Selects one of the known DDS formats; can be
			       used to specify DDS1 or DDS2, as required.

		DLT	       Selects one of the known DLT formats; can be
			       used to specify DLT42500_24, DLT42500_56,
			       DLT62500_64, DLT81633_64, or DLT85937_52, as
			       required.

		QIC	       Selects one of the known QIC formats; can be
			       used to specify QIC11, QIC24, QIC120, QIC150,
			       QIC525, QIC1000, QIC1350, QIC2100, QIC2GB, or
			       QIC5GB, as required.





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		D8MM	       Selects one of the known 8MM formats; can be
			       used to specify D8MM8200 or D8MM8500, as
			       required.

		D	       Selects a reel-to-reel density; can be used
			       to specify D800, D1600, or D6250, as
			       required.

		D3480	       Specifies that the device special file
			       communicates with a 3480 device.	 (There is
			       only one density option for 3480.)

		D[#]	       Specifies density as a numeric value to be
			       placed in the SCSI mode select block
			       descriptor.  The header file <sys/mtio.h>
			       contains a list of the standard density
			       codes.  The numeric value is used only for
			       density codes which cannot be found in this
			       list.

      C[#]	Write data in compressed mode, on tape drives that support
		data compression.  If a number is included, use it to
		specify a compression algorithm specific to the device.
		Note, compression is also provided when the density field is
		set to BEST.

      n		No rewind on close.  Unless this mode is requested, the tape
		is automatically rewound upon close.

      b		Specifies Berkeley-style tape behavior.	 When the b is
		absent, the tape drive follows AT&T-style behavior.  The
		details are described in "Tape Behavioral Characteristics"
		below.

      f#	Specify format (or density) value encoded in the minor
		number.	 The meaning of the value is dependent on the type
		of tape device in use.	(Used for short file name notation
		only.)

      i#	Specify an internal Property Table index value maintained by
		the tape driver, containing an array of configuration
		options.  The contents of this table are not directly
		accessible.  Use the lssf(1M) command to determine which
		configuration options are invoked.  (Used for short file
		name notation only.)

    Sample Tape Device Special File Names
      For a QIC150 device at SCSI address 3, card instance 2, with default
      block size, buffered mode, and AT&T-style with rewind on close, the
      standard device special file name is /dev/rmt/c2t3d0QIC150.




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      For a device at card instance 1, target 2, LUN 3, with exhaustive mode
      enabled (see DEPENDENCIES), fixed block size of 512 bytes, DDS1
      density with compression, AT&T-style with no rewind on close, the
      standard device file special name is /dev/rmt/c1t2d3es512DDS1Cn.

      For a system requiring short file names, the same device special file
      would be named /dev/rmt/c1t2d3i<&lt&lt&lt;#>&gt&gt&gt;n, where <&lt&lt&lt;#>&gt&gt&gt; is an index value
      selected by the tape driver.

      Use the lssf(1M) command to determine which configuration options are
      actually used with any device file.  The naming convention defined
      above should indicate the options used, but device files may be
      created with any user defined name.

    Tape Behavioral Characteristics
      When opened for reading or writing, the tape is assumed to be
      positioned as desired.

      When a file opened for writing is closed, two consecutive EOF (End of
      File) marks are written if, and only if, one or more writes to the
      file have occurred.  The tape is rewound unless the no-rewind mode has
      been specified, in which case the tape is positioned before the second
      EOF just written.	 For QIC devices only one EOF mark is written and
      the tape is positioned after the EOF mark (if the no-rewind mode has
      been specified).

      When a file open for reading (only) is closed and the no-rewind bit is
      not set, the tape is rewound.  If the no-rewind bit is set, the
      behavior depends on the style mode.  For AT&T-style devices, the tape
      is positioned after the EOF following the data just read (unless
      already at BOT or Filemark).  For Berkeley-style devices, the tape is
      not repositioned in any way.

      Each read(2) or write(2) call reads or writes the next record on the
      tape.  For writes, the record has the same length as the buffer given
      (within the limits of the hardware).

      During a read, the record size is passed back as the number of bytes
      read, up to the buffer size specified.  Since the minimum read length
      on a tape device is a complete record (to the next record mark), the
      number of bytes ignored (for records longer than the buffer size
      specified) is available in the mt_resid field of the mtget structure
      via the MTIOCGET call of ioctl(2).  Current restrictions require tape
      device application programs to use 2-byte alignment for buffer
      locations and I/O sizes.	To allow for more stringent future
      restrictions (4-byte aligned, etc.) and to maximize performance, page
      alignment is suggested.  For example, if the target buffer is
      contained within a structure, care must be taken that structure
      elements before the buffer allow the target buffer to begin on an even
      address. If need be, placing a filler integer before the target buffer
      will insure its location on a 4-byte boundary.



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      The ascending hierarchy of tape marks is defined as follows: record
      mark, filemark (EOF), setmark and EOD (End of Data). Not all devices
      support all types of tape marks but the positioning within the
      hierarchy holds true.  Each type of mark is typically used to contain
      one or more of the lesser marks.

      When spacing over a number of a particular type of tape mark,
      hierarchically superior marks (except EOD) do not terminate tape
      motion and are included in the count. For instance, MTFSR can be used
      to pass over record marks and filemarks.

      Reading an EOF mark is returned as a successful zero-length read; that
      is, the data count returned is zero and the tape is positioned after
      the EOF, enabling the next read to return the next record.

      DDS devices and the 8mm 8505 device also support setmarks , which are
      used to delineate a group (set) of files.	 For the 8mm 8505 setmarks
      are only supported when the density is set to 8500 plus compression.
      Reading a setmark is also returned as a zero-length read.	 Filemarks,
      setmarks and EOD can be distinguished by unique bits in the mt_gstat
      field.

      Spacing operations (back or forward space, setmark, file or record)
      position past the object being spaced to in the direction of motion.
      For example, back-spacing a file leaves the tape positioned before the
      file mark; forward-spacing a file leaves the tape positioned after the
      file mark.  This is consistent with standard tape usage.

      For QIC devices, spacing operations can take a very long time.  In the
      worst case, a space command could take as much as 2 hours!  While this
      command is in progress, the device is not accessible for any other
      commands.

      lseek(2) type seeks on a magnetic tape device are ignored.  Instead,
      the ioctl(2) operations below can be used to position the tape and
      determine its status.

      The header file <sys/mtio.h> has useful information for tape handling.
      The following is included from <sys/mtio.h> and describes the possible
      tape operations:

	   /* mag tape I/O control requests */

	   #define  MTIOCTOP  _IOW('m', 1, struct mtop)	 /* do mag tape op */
	   #define  MTIOCGET  _IOR('m', 2, struct mtget) /* get tape status */

	   /* structure for MTIOCTOP - mag tape op command */

	   struct mtop {
	       short mt_op;	    /* operations defined below */
	       daddr_t mt_count;    /* how many of them */



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	   };

	   /* operations */

	   #define MTWEOF 0  /* write filemark (end-of-file record) */
	   #define MTFSF  1  /* forward space file */
	   #define MTBSF  2  /* backward space file */
	   #define MTFSR  3  /* forward space record */
	   #define MTBSR  4  /* backward space record */
	   #define MTREW  5  /* rewind */
	   #define MTOFFL 6  /* rewind and put the drive offline (may eject) */
	   #define MTNOP  7  /* no operation, may set status */
	   #define MTEOD  8  /* DDS, QIC and 8MM only - seek to end-of-data */
	   #define MTWSS  9  /* DDS and 8MM only - write setmark(s) */
	   #define MTFSS 10  /* DDS and 8MM only - space forward setmark(s) */
	   #define MTBSS 11  /* DDS and 8MM only - space backward setmark(s) */
	   #define MTSTARTVOL 12  /* Start a new volume (for ATS) */
	   #define MTENDVOL 13	/* Terminate a volume (for ATS) */
	   #define MTRES 14  /* Reserve Device */
	   #define MTREL 15  /* Release Device */
	   #define MTERASE 16  /* Erase media */

	   /* structure for MTIOCGET - mag tape get status command */

	   struct mtget {
		long	   mt_type;	/* type of magtape device */
		long	   mt_resid;	/* residual count */

	   /* The following two registers are device dependent */

		long	   mt_dsreg1;	 /* status register (msb) */
		long	   mt_dsreg2;	 /* status register (lsb) */

	   /* The following are device-independent status words */

		long	   mt_gstat;	 /* generic status */
		long	   mt_erreg;	 /* error register */
		daddr_t	   mt_fileno;	 /* No longer used - always set to -1 */
		daddr_t	   mt_blkno;	 /* No longer used - always set to -1 */

      Information for decoding the mt_type field can be found in
      <sys/mtio.h>.

    Other Tape Status Characteristics
      Efficient use of streaming tape drives with large internal buffers and
      immediate-reporting require the following end-of-tape procedures:

	   All writes near LEOT (Logical End of Tape) complete without error
	   if actually written to the tape. Once the tape driver determines
	   that LEOT has been passed, subsequent writes do not occur and an
	   error message is returned.



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	   To write beyond this point (keep in mind that streaming drives
	   have already written well past LEOT), simply ask for status using
	   the MTIOCGET ioctl.	If status reflects the EOT condition, the
	   driver drops all write barriers.  For reel-to-reel devices,
	   caution must be exercised to keep the tape on the reel.

      When immediate-reporting is enabled, the tape2 driver will drop out of
      immediate mode and flush the device buffer with every write filemark
      or write setmark.	 The stape driver will flush the device buffers when
      a write filemark or write setmark command is given with the count set
      to zero.

      When immediate-reporting is disabled, the write encountering LEOT
      returns an error with the tape driver automatically backing up over
      that record.

      When reading near the end-of-tape, the user is not informed of LEOT.
      Instead, the typical double EOF marks or a pre-arranged data pattern
      signals the logical end-of-tape.

      Since magnetic tape drives vary in EOT sensing due to differences in
      the physical placement of sensors, any application (such as multiple-
      tape cpio(1) backups) requiring that data be continued from the EOT
      area of one tape to another tape must be restricted.  Therefore, the
      tape drive type and mode should be identical for the creation and
      reading of the tapes.

      The following macros are defined in <sys/mtio.h> for decoding the
      status field mt_gstat returned from MTIOCGET.  For each macro, the
      input parameter <x> is the mt_gstat field.

	   GMT_BOT(x)		    Returns TRUE at beginning of tape.

	   GMT_EOD(x)		    Returns TRUE if End-of-Data is
				    encountered for DDS, QIC or 8MM.

	   GMT_EOF(x)		    Returns TRUE at an End-of-File mark.

	   GMT_EOT(x)		    Returns TRUE at end of tape.

	   GMT_IM_REP_EN(x)	    Returns TRUE if immediate reporting mode
				    is enabled.

	   GMT_ONLINE(x)	    Returns TRUE if drive is on line.

	   GMT_SM(x)		    Returns TRUE if setmark is encountered.

	   GMT_WR_PROT(x)	    Returns TRUE if tape is write protected.

	   GMT_COMPRESS(x)	    Returns TRUE if data compression is
				    enabled.



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	   GMT_DENSITY(x)	    Returns the currently configured 8-bit
				    density value.  Supported values are
				    defined in <sys/mtio.h>.

	   GMT_QIC_FORMAT(x) and GMT_8mm_FORMAT(x)
				    Return the same information as does
				    GMT_DENSITY(x).  GMT_DENSITY(x) is
				    preferred because GMT_QIC_FORMAT and
				    GMT_8mm_FORMAT may be obsoleted at some
				    future date.

	   GMT_D_800(x)		    Returns TRUE if the density encoded in
				    mt_gstat is 800 bpi.

	   GMT_D_1600(x)	    Returns TRUE if the density encoded in
				    mt_gstat is 1600 bpi.

	   GMT_D_6250(x)	    Returns TRUE if the density encoded in
				    mt_gstat is 6250 bpi (with or without
				    compression).

	   GMT_D_6250c(x)	    Returns TRUE if the density encoded in
				    mt_gstat is 6250 bpi plus compression.

	   GMT_D_DDS1(x)	    Returns TRUE if the density encoded in
				    mt_gstat is DDS1 (with or without
				    compression).

	   GMT_D_DDS1c(x)	    Returns TRUE if the density encoded in
				    mt_gstat is DDS1 plus compression.

	   GMT_D_DDS2(x)	    Returns TRUE if the density encoded in
				    mt_gstat is DDS2 (with or without
				    compression).

	   GMT_D_DDS2c(x)	    Returns TRUE if the density encoded in
				    mt_gstat is DDS2 plus compression.

	   GMT_D_DLT_42500_24(x)    Returns TRUE if the density encoded in
				    mt_gstat is 42500 bpi, 24 track pairs.

	   GMT_D_DLT_42500_56(x)    Returns TRUE if the density encoded in
				    mt_gstat is 42500 bpi, 56 track pairs.

	   GMT_D_DLT_62500_64(x)    Returns TRUE if the density encoded in
				    mt_gstat is 62500 bpi (with or without
				    compression).

	   GMT_D_DLT_62500_64c(x)   Returns TRUE if the density encoded in
				    mt_gstat is 62500 bpi plus compression.




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	   GMT_D_DLT_81633_64(x)    Returns TRUE if the density encoded in
				    mt_gstat is 81633 bpi (with or without
				    compression).

	   GMT_D_DLT_81633_64c(x)   Returns TRUE if the density encoded in
				    mt_gstat is 81633 bpi plus compression.

	   GMT_D_DLT_85937_52(x)    Returns TRUE if the density encoded in
				    mt_gstat is 85937 bpi (with or without
				    compression).

	   GMT_D_DLT_85937_52c(x)   Returns TRUE if the density encoded in
				    mt_gstat is 85937 bpi plus compression.

	   GMT_D_3480(x)	    Returns TRUE if the density encoded in
				    mt_gstat is for a 3480 device (with or
				    without compression).

	   GMT_D_3480c(x)	    Returns TRUE if the density encoded in
				    mt_gstat is for a 3480 device with
				    compression.

	   GMT_D_QIC_11(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-11 format.

	   GMT_D_QIC_24(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-24 format.

	   GMT_D_QIC_120(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-120 format.

	   GMT_D_QIC_150(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-150 format.

	   GMT_D_QIC_525(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-525 format.

	   GMT_D_QIC_1000(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-1000 format.

	   GMT_D_QIC_1350(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-1350 format.

	   GMT_D_QIC_2100(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-2100 format.

	   GMT_D_QIC_2GB(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-2GB format.

	   GMT_D_QIC_5GB(x)	    Returns TRUE if the density encoded in
				    mt_gstat is QIC-5GB format.



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	   GMT_D_8MM_8200(x)	    Returns TRUE if the density encoded in
				    mt_gstat is 8 millimeter 8200 format
				    (with or without compression).

	   GMT_D_8MM_8200c(x)	    Returns TRUE if the density encoded in
				    mt_gstat is 8 millimeter 8200 format
				    with compression.

	   GMT_D_8MM_8500(x)	    Returns TRUE if the density encoded in
				    mt_gstat is 8 millimeter 8500 format
				    (with or without compression).

	   GMT_D_8MM_8500c(x)	    Returns TRUE if the density encoded in
				    mt_gstat is 8 millimeter 8500 format
				    with compression.

	   GMT_MEDIUM(x)	    Identifies the 8-bit medium type value
				    describing the tape currently loaded
				    into the tape device.  The reported
				    value is only valid for QIC and 8mm
				    devices.  Supported values are defined
				    in <sys/mtio.h>.

	   GMT_QIC_MEDIUM(x)	    Returns the same information as does
				    GMT_MEDIUM(x).  GMT_MEDIUM(x) is
				    preferred because GMT_QIC_MEDIUM may be
				    obsoleted at some future date.

	   GMT_DR_OPEN(x)	    Does not apply to any currently
				    supported devices.	Always returns
				    FALSE.

      HP-UX silently enforces a tape record blocking factor (MAXPHYS) on
      large I/O requests.  For example, a user write request with a length
      of ten times MAXPHYS will actually reach the media as ten separate
      records.	A subsequent read (with ten times MAXPHYS as a length) will
      look like a single operation to the user, even though HP-UX has broken
      it up into ten separate read requests to the driver.  The blocking
      function is transparent to the user during writes.  It is also
      transparent during reads unless:

	   +  The user picks an arbitrary read length greater than MAXPHYS.

	   +  The user attempts to read a third-party tape containing
	      records larger than MAXPHYS.

      Since the value for MAXPHYS is relatively large (usually >= 256K
      bytes), this is typically not a problem.

      The MTNOP operation does not set the device-independent status word.




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      3480 stacker devices are supported only in auto (that is, sequential-
      access) mode.  To advance to the next tape in the stack, an MTIOCTOP
      control request specifying an MTOFFL operation should be issued.	An
      MTIOCGET control request should then be issued to determine whether or
      not the stacker has been successfully advanced.  Failure on the
      MTIOCGET operation (or an offline status) indicates that no more tapes
      are available in the stacker, the stacker has been ejected, and user
      intervention is required to load a new stack.

 EXAMPLES
      Assuming that fd is a valid file descriptor, the following example
      writes two consecutive filemarks on the tape:

	   #include <&lt&lt&lt;sys/types.h>&gt&gt&gt;
	   #include <&lt&lt&lt;sys/mtio.h>&gt&gt&gt;

	   struct  mtop mtop;

	   mtop.mt_op = MTWEOF;
	   mtop.mt_count = 2;
	   ioctl(fd, MTIOCTOP, &&amp&amp&amp;mtop);

      If fd is a valid file descriptor for an open DDS drive, the following
      example spaces forward to just past the next setmark:

	   #include <&lt&lt&lt;sys/types.h>&gt&gt&gt;
	   #include <&lt&lt&lt;sys/mtio.h>&gt&gt&gt;

	   struct  mtop mtop;

	   mtop.mt_op = MTFSS;
	   mtop.mt_count = 1;
	   ioctl(fd, MTIOCTOP, &&amp&amp&amp;mtop);

      Given that fd is a valid file descriptor for an opened tape device,
      and that it has just returned 0 from a read(2) request.  The following
      system call verifies that the tape has just read a filemark:

	   #include <&lt&lt&lt;sys/types.h>&gt&gt&gt;
	   #include <&lt&lt&lt;sys/mtio.h>&gt&gt&gt;

	   struct mtget mtget;

	   ioctl(fd, MTIOCGET, &&amp&amp&amp;mtget);
	   if (GMT_EOF (mtget.mt_gstat)) {
	   /* code for filemark detection */
	   }

 WARNINGS
      Density specifications BEST (standard naming convention) or f0
      (alternate naming convention) activate data compression on tape



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      devices which support compression.  This is also true for the files
      using the pre-HP-UX 10.0 naming convention which are linked to these
      files (see "Naming Conventions" above).

      This means that a tape written using one of the eight device files
      (which are automatically created when the system is initialized) on a
      tape device which supports data compression, will contain compressed
      data.  This tape cannot be successfully read on a tape device which
      does not support compressed data.	 For example, a tape written (using
      one of the eight automatically created device files) on a newer DDS
      device which supports data compression cannot be read on an older DDS
      device which does not support data compression.

      To accomplish data interchange between devices in a case such as this,
      a new device file must be manually created using the mksf(1M) command.
      In the above example, the options specified to mksf(1M) should include
      a density option with an argument of DDS1, and must not include a
      compression option.

      Use the mksf(1M) command instead of the mknod(1M) command to create
      tape device files.  As of the 10.0 release, there are more
      configuration options than will fit in the device file's minor number.
      Prior to the 10.0 release, it was possible to select configuration
      options by directly setting the bits in the device special file's
      minor number using mknod(1M).

      As of the 10.0 release, a base set of configuration options are
      contained in the minor number.  Extended configuration options are
      stored in a table of configuration properties.  The minor number may
      contain an index into the property table, which is maintained by the
      tape driver and is not directly visible to the user.  The mksf(1M)
      command sets the minor number and modifies the property table as
      needed based on mnemonic parameters passed into the command.

      If your device configuration requirements are limited to the base set
      of options, you need not be concerned with the property table.  The
      base configuration options are as follows:

	   +  hardware address (card instance, target, and unit number)

	   +  density (from the set of pre-defined options listed in
	      mksf(1M))

	   +  compression (using the default compression algorithm)

	   +  rewind or no rewind

	   +  Berkeley	or  AT&T mode

      All other configuration options are extended options that result in
      use of the property table.



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      It is recommended that all tape device files be put in the /dev/rmt
      directory.  All tape device files using extended configuration options
      must be put in the /dev/rmt directory.  This is required for proper
      maintenance of the property table.  Device files using a extended
      configuration options located outside the /dev/rmt directory may not
      provide consistent behavior across system reboots.

      Use the rmsf(1M) command to clean up unused device files.	 Otherwise,
      the property table may overflow and cause the mksf(1M) command to
      fail.

      Density codes listed in <sys/mtio.h> have device-dependent behaviors.
      See the hardware manual for your tape device to find which densities
      are valid.  For some devices, these values may be referred to as
      formats instead of densities.

      Use of unbuffered mode can reduce performance and increase media wear.

      Reads and writes from/to older (fixed block) devices such as QIC150
      must occur at exact multiples of the supported block size.

      Write operations on a QIC device can be initiated only at BOT or EOD.
      QIC devices will not allow writes with the tape positioned in the
      middle of recorded data.

      The offline operation puts the QIC drive offline.	 The cartridge is
      not ejected as is done for DDS.  To put the drive back online, the
      cartridge has to be manually ejected and then reinserted.

      Sequential-access devices that use the SCSI I/O interface may not
      always report true media position.

      On a 3480 device with data compression enabled, writing of a single
      record that cannot be compressed to less than 102,400 bytes is not
      supported.

      Note that using the 8200 format on 8500-style 8mm devices will
      significantly reduce tape capacity, and that only the 8500c-density
      setting provides support for setmarks.

      The maximum I/O request for 8mm devices is limited to 240KB.

 DEPENDENCIES
    Driver-Specific Options for stape (major number 205)
      The following options may be used in creating device special files for
      tape drives that access the stape driver:

      e	      Exhaustive mode is enabled (default is disabled).
	      When exhaustive mode is enabled, the driver will, if
	      necessary, attempt several different configuration options
	      when opening a device.  The first attempt follows the minor



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	      number configuration exactly, but if that fails, the driver
	      attempts other likely configuration values.

	      With Exhaustive mode disabled, the driver makes only one
	      attempt to configure a device using the configuration
	      indicated in the minor number.

      p	      Specifies a partitioned tape whose currently active partition
	      is partition 1 (closest to BOT (beginning of tape)).  Optional
	      partition 1 is closest to BOT for possible use as a volume
	      directory.  The default partition without this option is
	      partition 0.  If partitioning is unsupported, the entire tape
	      is referred to as partition 0.

      s[#]    Specifies fixed-block mode; the optional number indicates the
	      block size.  If the number is not present, the driver selects
	      a default block size appropriate to the device type.

    Driver Specific Options for tape2 (major number 212)
      The following options may be used in creating device special files for
      tape drives that access the tape2 driver:

      o	      Diagnostic messages to the console are suppressed.

      z	      The tape driver will attempt to mimic the behavior of RTE
	      systems;	that is, the driver will not do any tape alteration
	      or movement when the device is closed.

 AUTHOR
      mt was developed by HP and the University of California, Berkeley.

 FILES
      /dev/rmt/*	       tape device special files
      <&lt&lt&lt;sys/mtio.h>&gt&gt&gt;	       constants and macros for use with tapes
      /etc/mtconfig	       configuration property table for tapes
      /dev/rmt/*config	       device files for accessing configuration
			       properties table - for internal use only

 SEE ALSO
      dd(1), mt(1), ioctl(2), insf(1M), lssf(1M), mksf(1M), rmsf(1M),

      Configuring HP-UX for Peripherals












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