MTIO(4) MidnightBSD 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 second 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 */

daddr_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 */

short

mt_resid;

/* residual count */

#if defined (__FreeBSD__)

daddr_t mt_blksiz;

/* presently operating blocksize */

daddr_t mt_density;

/* presently operating density */

u_int32_t mt_comp;

/* presently operating compression */

daddr_t mt_blksiz0;

/* blocksize for mode 0 */

daddr_t mt_blksiz1;

/* blocksize for mode 1 */

daddr_t mt_blksiz2;

/* blocksize for mode 2 */

daddr_t mt_blksiz3;

/* blocksize for mode 3 */

daddr_t mt_density0;

/* density for mode 0 */

daddr_t mt_density1;

/* density for mode 1 */

daddr_t mt_density2;

/* density for mode 2 */

daddr_t mt_density3;

/* density for mode 3 */

/* the following are not yet implemented */

u_int32_t mt_comp0;

/* compression type for mode 0 */

u_int32_t mt_comp1;

/* compression type for mode 1 */

u_int32_t mt_comp2;

/* compression type for mode 2 */

u_int32_t mt_comp3;

/* compression type for mode 3 */

/* end not yet implemented */
#endif

daddr_t

mt_fileno;

/* relative file number of current position */

daddr_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.

*/

u_int8_t io_sense[32];

/* Last Sense Data For Data I/O */

u_int32_t io_resid;

/* residual count from last Data I/O */

u_int8_t io_cdb[16];

/* Command that Caused the Last Data Sense */

u_int8_t ctl_sense[32];

/* Last Sense Data For Control I/O */

u_int32_t ctl_resid;

/* residual count from last Control I/O */

u_int8_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 {

u_int32_t retries;

/* total # retries performed */

u_int32_t corrected;

/* total # corrections performed */

u_int32_t processed;

/* total # corrections successful */

u_int32_t failures;

/* total # corrections/retries failed */

u_int64_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, u_int32_t)

/* get logical blk addr */

#define

MTIOCRDHPOS

_IOR(’m’, 6, u_int32_t)

/* get hardware blk addr */

#define

MTIOCSLOCATE

_IOW(’m’, 5, u_int32_t)

/* seek to logical blk addr */

#define

MTIOCHLOCATE

_IOW(’m’, 6, u_int32_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, u_int32_t)

/* Get current EOT model */

#define

MTIOCGETEOTMODEL

_IOR(’m’, 8, u_int32_t)

#ifndef _KERNEL

#define

DEFTAPE

"/dev/nsa0"

#endif

#ifdef

_KERNEL

/*
* minor device number
*/

#define

T_UNIT

003

/* unit selection */

#define

T_NOREWIND

004

/* no rewind on close */

#define

T_DENSEL

030

/* density select */

#define

T_800BPI

000

/* select 800 bpi */

#define

T_1600BPI

010

/* select 1600 bpi */

#define

T_6250BPI

020

/* select 6250 bpi */

#define

T_BADBPI

030

/* undefined selection */

#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 understandable manner.

MidnightBSD 0.3 February 11, 1996 MidnightBSD 0.3