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MTIO(4)		       FreeBSD Kernel Interfaces Manual		       MTIO(4)

NAME
     mtio -- FreeBSD magtape interface

DESCRIPTION
     The special files named /dev/[n]sa* refer to SCSI tape drives, which may
     be	attached to the	system.	 /dev/[n]sa*.ctl are control devices that can
     be	used to	issue ioctls to	the SCSI tape driver to	set parameters that
     are required to last beyond the unmounting	of a tape.

     The rewind	devices	automatically rewind when the last requested read,
     write or seek has finished, or the	end of the tape	has been reached.  The
     letter `n'	is usually prepended to	the name of the	no-rewind devices.

     Tapes can be written with either fixed length records or variable length
     records.  See sa(4) for more information.	Two end-of-file	markers	mark
     the end of	a tape,	and one	end-of-file marker marks the end of a tape
     file.  If the tape	is not to be rewound it	is positioned with the head in
     between the two tape marks, where the next	write will over	write the sec-
     ond end-of-file marker.

     All of the	magtape	devices	may be manipulated with	the mt(1) command.

     A number of ioctl(2) operations are available on raw magnetic tape.  The
     following definitions are from <sys/mtio.h>:

     #ifndef _SYS_MTIO_H_
     #define _SYS_MTIO_H_

     #ifndef _KERNEL
     #include <sys/types.h>
     #endif
     #include <sys/ioccom.h>

     /*
      *	Structures and definitions for mag tape	io control commands
      */

     /*	structure for MTIOCTOP - mag tape op command */
     struct mtop {
	     short   mt_op;	     /*	operations defined below */
	     int32_t mt_count;	     /*	how many of them */
     };

     /*	operations */
     #define MTWEOF	     0	     /*	write an 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 */
     #define MTNOP	     7	     /*	no operation, sets status only */
     #define MTCACHE	     8	     /*	enable controller cache	*/
     #define MTNOCACHE	     9	     /*	disable	controller cache */

     #if defined(__FreeBSD__)
     /*	Set block size for device. If device is	a variable size	dev	     */
     /*	a non zero parameter will change the device to a fixed block size    */
     /*	device with block size set to that of the parameter passed in.	     */
     /*	Resetting the block size to 0 will restore the device to a variable  */
     /*	block size device. */

     #define MTSETBSIZ	     10

     /*	Set density values for device. Sets the	value for the opened mode only.	*/

     #define MTSETDNSTY	     11

     #define MTERASE	     12	     /*	erase to EOM */
     #define MTEOD	     13	     /*	Space to EOM */
     #define MTCOMP	     14	     /*	select compression mode	0=off, 1=def */
     #define MTRETENS	     15	     /*	re-tension tape	*/
     #define MTWSS	     16	     /*	write setmark(s) */
     #define MTFSS	     17	     /*	forward	space setmark */
     #define MTBSS	     18	     /*	backward space setmark */

     #define MT_COMP_ENABLE	     0xffffffff
     #define MT_COMP_DISABLED	     0xfffffffe
     #define MT_COMP_UNSUPP	     0xfffffffd

     /*
      *	Values in mt_dsreg that	say what the device is doing
      */
     #define MTIO_DSREG_NIL  0	     /*	Unknown	*/
     #define MTIO_DSREG_REST 1	     /*	Doing Nothing */
     #define MTIO_DSREG_RBSY 2	     /*	Communicating with tape	(but no	motion)	*/
     #define MTIO_DSREG_WR   20	     /*	Writing	*/
     #define MTIO_DSREG_FMK  21	     /*	Writing	Filemarks */
     #define MTIO_DSREG_ZER  22	     /*	Erasing	*/
     #define MTIO_DSREG_RD   30	     /*	Reading	*/
     #define MTIO_DSREG_FWD  40	     /*	Spacing	Forward	*/
     #define MTIO_DSREG_REV  41	     /*	Spacing	Reverse	*/
     #define MTIO_DSREG_POS  42	     /*	Hardware Positioning (direction	unknown) */
     #define MTIO_DSREG_REW  43	     /*	Rewinding */
     #define MTIO_DSREG_TEN  44	     /*	Retensioning */
     #define MTIO_DSREG_UNL  45	     /*	Unloading */
     #define MTIO_DSREG_LD   46	     /*	Loading	*/

     #endif  /*	__FreeBSD__ */

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

     struct mtget {
	     short   mt_type;	     /*	type of	magtape	device */
     /*	the following two registers are	grossly	device dependent */
	     short   mt_dsreg;	     /*	``drive	status'' register */
	     short   mt_erreg;	     /*	``error'' register */
     /*	end device-dependent registers */
	     /*
	      *	Note that the residual count, while maintained,	may be
	      *	be nonsense because the	size of	the residual may (greatly)
	      *	exceed 32 K-bytes. Use the MTIOCERRSTAT	ioctl to get a
	      *	more accurate count.
	      */
	     short   mt_resid;	     /*	residual count */
     #if defined (__FreeBSD__)
	     int32_t mt_blksiz;	     /*	presently operating blocksize */
	     int32_t mt_density;     /*	presently operating density */
	     uint32_t mt_comp;	     /*	presently operating compression	*/
	     int32_t mt_blksiz0;     /*	blocksize for mode 0 */
	     int32_t mt_blksiz1;     /*	blocksize for mode 1 */
	     int32_t mt_blksiz2;     /*	blocksize for mode 2 */
	     int32_t mt_blksiz3;     /*	blocksize for mode 3 */
	     int32_t mt_density0;    /*	density	for mode 0 */
	     int32_t mt_density1;    /*	density	for mode 1 */
	     int32_t mt_density2;    /*	density	for mode 2 */
	     int32_t mt_density3;    /*	density	for mode 3 */
     /*	the following are not yet implemented */
	     uint32_t mt_comp0;	     /*	compression type for mode 0 */
	     uint32_t mt_comp1;	     /*	compression type for mode 1 */
	     uint32_t mt_comp2;	     /*	compression type for mode 2 */
	     uint32_t mt_comp3;	     /*	compression type for mode 3 */
     /*	end not	yet implemented	*/
     #endif
	     int32_t mt_fileno;	     /*	relative file number of	current	position */
	     int32_t mt_blkno;	     /*	relative block number of current position */
     };

     /*	structure for MTIOCERRSTAT - tape get error status command */
     /*	really only supported for SCSI tapes right now */
     struct scsi_tape_errors {
	     /*
	      *	These are latched from the last	command	that had a SCSI
	      *	Check Condition	noted for these	operations. The	act
	      *	of issuing an MTIOCERRSTAT unlatches and clears	them.
	      */
	     uint8_t io_sense[32];   /*	Last Sense Data	For Data I/O */
	     int32_t io_resid;	     /*	residual count from last Data I/O */
	     uint8_t io_cdb[16];     /*	Command	that Caused the	Last Data Sense	*/
	     uint8_t ctl_sense[32];  /*	Last Sense Data	For Control I/O	*/
	     int32_t ctl_resid;	     /*	residual count from last Control I/O */
	     uint8_t ctl_cdb[16];    /*	Command	that Caused the	Last Control Sense */
	     /*
	      *	These are the read and write cumulative	error counters.
	      *	(how to	reset cumulative error counters	is not yet defined).
	      *	(not implemented as yet	but space is being reserved for	them)
	      */
	     struct {
		     uint32_t retries;	     /*	total #	retries	performed */
		     uint32_t corrected;     /*	total #	corrections performed */
		     uint32_t processed;     /*	total #	corrections successful */
		     uint32_t failures;	     /*	total #	corrections/retries failed */
		     uint64_t nbytes;	     /*	total #	bytes processed	*/
	     } wterr, rderr;
     };

     union mterrstat {
	     struct scsi_tape_errors scsi_errstat;
	     char _reserved_padding[256];
     };

     /*
      *	Constants for mt_type byte.  These are the same
      *	for controllers	compatible with	the types listed.
      */
     #define MT_ISTS	     0x01	     /*	TS-11 */
     #define MT_ISHT	     0x02	     /*	TM03 Massbus: TE16, TU45, TU77 */
     #define MT_ISTM	     0x03	     /*	TM11/TE10 Unibus */
     #define MT_ISMT	     0x04	     /*	TM78/TU78 Massbus */
     #define MT_ISUT	     0x05	     /*	SI TU-45 emulation on Unibus */
     #define MT_ISCPC	     0x06	     /*	SUN */
     #define MT_ISAR	     0x07	     /*	SUN */
     #define MT_ISTMSCP	     0x08	     /*	DEC TMSCP protocol (TU81, TK50)	*/
     #define MT_ISCY	     0x09	     /*	CCI Cipher */
     #define MT_ISCT	     0x0a	     /*	HP 1/4 tape */
     #define MT_ISFHP	     0x0b	     /*	HP 7980	1/2 tape */
     #define MT_ISEXABYTE    0x0c	     /*	Exabyte	*/
     #define MT_ISEXA8200    0x0c	     /*	Exabyte	EXB-8200 */
     #define MT_ISEXA8500    0x0d	     /*	Exabyte	EXB-8500 */
     #define MT_ISVIPER1     0x0e	     /*	Archive	Viper-150 */
     #define MT_ISPYTHON     0x0f	     /*	Archive	Python (DAT) */
     #define MT_ISHPDAT	     0x10	     /*	HP 35450A DAT drive */
     #define MT_ISMFOUR	     0x11	     /*	M4 Data	1/2 9track drive */
     #define MT_ISTK50	     0x12	     /*	DEC SCSI TK50 */
     #define MT_ISMT02	     0x13	     /*	Emulex MT02 SCSI tape controller */

     /*	mag tape io control commands */
     #define MTIOCTOP	     _IOW('m', 1, struct mtop)	     /*	do a mag tape op */
     #define MTIOCGET	     _IOR('m', 2, struct mtget)	     /*	get tape status	*/
     /*	these two do not appear	to be used anywhere */
     #define MTIOCIEOT	     _IO('m', 3)		     /*	ignore EOT error */
     #define MTIOCEEOT	     _IO('m', 4)		     /*	enable EOT error */
     /*
      *	When more SCSI-3 SSC (streaming	device)	devices	are out	there
      *	that support the full 32 byte type 2 structure,	we'll have to
      *	rethink	these ioctls to	support	all the	entities they haul into
      *	the picture (64	bit blocks, logical file record	numbers, etc..).
      */
     #define MTIOCRDSPOS     _IOR('m', 5, uint32_t)  /*	get logical blk	addr */
     #define MTIOCRDHPOS     _IOR('m', 6, uint32_t)  /*	get hardware blk addr */
     #define MTIOCSLOCATE    _IOW('m', 5, uint32_t)  /*	seek to	logical	blk addr */
     #define MTIOCHLOCATE    _IOW('m', 6, uint32_t)  /*	seek to	hardware blk addr */
     #define MTIOCERRSTAT    _IOR('m', 7, union	mterrstat)   /*	get tape errors	*/
     /*
      *	Set EOT	model- argument	is number of filemarks to end a	tape with.
      *	Note that not all possible values will be accepted.
      */
     #define MTIOCSETEOTMODEL	     _IOW('m', 8, uint32_t)
     /*	Get current EOT	model */
     #define MTIOCGETEOTMODEL	     _IOR('m', 8, uint32_t)

     #ifndef _KERNEL
     #define DEFTAPE "/dev/nsa0"
     #endif

     #endif /* !_SYS_MTIO_H_ */

FILES
     /dev/[n]sa*

SEE ALSO
     mt(1), tar(1), ast(4), sa(4)

HISTORY
     The mtio manual appeared in 4.2BSD.  An i386 version first	appeared in
     FreeBSD 2.2.

BUGS
     The status	should be returned in a	device independent format.

     The special file naming should be redone in a more	consistent and under-
     standable manner.

FreeBSD	10.1		       November	11, 2011		  FreeBSD 10.1

NAME | DESCRIPTION | FILES | SEE ALSO | HISTORY | BUGS

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