MTIO

Section: Devices and Network Interfaces (4)
Updated: vax
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BSD mandoc
BSD 4.2  

NAME

mtio - UNIX magtape interface  

DESCRIPTION

The special files named /dev/mt0 and /dev/rmt0 through /dev/mt23 and /dev/rmt23 refer to UNIX magtape drives, which may be on the MASSBUS using the TM03 formatter ht(4), or TM78 formatter, mt(4), or on the UNIBUS using either the TM11 or TS11 formatters tm(4), TU45 compatible formatters, ut(4), or ts(4). These devices are typical tape block devices, see physio(4).

The following table of the converntional device names is applicable to any of the transport/controller pairs. (But note that only 1600 BPI is available with the TS11 .

        800 BPI    1600 BPI   6500 BPI
or lowest density       or second density       or third density


Rewind   mt0/rmt0    mt8/rmt8   mt16/rmt16
Rewind   mt1/rmt1    mt9/rmt9   mt17/rmt17
Rewind   mt2/rmt2    mt10/rmt10         mt18/rmt18
Rewind   mt3/rmt3    mt11/rmt11         mt19/rmt19
No-rewind        nmt4/nrmt4   nmt12/nrmt12         nmt20/nrmt20
No-rewind        nmt5/nrmt5   nmt13/nrmt13         nmt21/nrmt21
No-rewind        nmt6/nrmt6   nmt14/nrmt14         nmt22/nrmt22
No-rewind        nmt7/nrmt7   nmt15/nrmt15         nmt23/nrmt32

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.

Unix tapes are written in multiples of 1024 byte block records. 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 Aq Pa sys/mtio.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 */

/* 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 */
/* the following two are not yet implemented */
        daddr_t mt_fileno;      /* file number of current position */
        daddr_t mt_blkno;       /* block number of current position */
/* end not yet implemented */
};

/*
 * 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 */

/* 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 */
#define MTIOCIEOT       _IO('m', 3)                     /* ignore EOT error */
#define MTIOCEEOT       _IO('m', 4)                     /* enable EOT error */

#ifndef KERNEL
#define DEFTAPE "/dev/rmt12"
#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

 

FILES

/dev/mt?
/dev/rmt?

 

SEE ALSO

mt(1), tar(1), tp(1), ht(4), tm(4), ts(4), mt(4), ut(4)  

HISTORY

The mtio manual appeared in BSD 4.2  

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.


 

Index

NAME
DESCRIPTION
FILES
SEE ALSO
HISTORY
BUGS

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Time: 06:48:53 GMT, May 19, 2025