MTIO

Section: Devices and Network Interfaces (4)
Index Return to Main Contents

BSD mandoc
 

NAME

mtio - UNIX magtape interface  

DESCRIPTION

The special files named /dev/cy0s /dev/cy15s are interfaces to the UNIX magtape drivers. For the Tahoe, these interfaces may be on the VERSABUS via a CIPHER tapemaster formatter cy(4). The files cy0s cy15s are read/written in 25 IPS , The density (1600 BPI or 3200 BPI is selected by a switch on the drive. The following table of device names applies to any of the transport/controller pairs.

Rewind No-rewind       Rewind  No-rewind cy0s/rcy0s   ncy0s/nrcy0s    cy8s/rcy8s      ncy8s/nrcy8s
cy1s/rcy1s      ncy1s/nrcy1s    cy9s/rcy9s      ncy9s/nrcy9s
cy2s/rcy2s      ncy2s/nrcy2s    cy10s/rcy10s    ncy10s/nrcy10s
cy3s/rcy3s      ncy3s/nrcy3s    cy11s/rcy11s    ncy11s/nrcy11s
cy4s/rcy4s      ncy4s/nrcy4s    cy12s/rcy12s    ncy12s/nrcy12s
cy5s/rcy5s      ncy5s/nrcy5s    cy13s/rcy13s    ncy13s/nrcy13s
cy6s/rcy6s      ncy6s/nrcy6s    cy14s/rcy14s    ncy14s/nrcy14s
cy7s/rcy7s      ncy7s/nrcy7s    cy15s/rcy15s    ncy15s/nrcy15s

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.

For compatibility with customary UNIX tape device names ``mt* '' the Bo Pa n Bc Pa cy*s files are linked to appropriate Bo Pa n Bc Em mt* files.

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 other 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/cy?
/dev/rcy?
Rewind devices.
/dev/ncy?
/dev/nrcy?
No-rewind devices.
/dev/[n]mt?
/dev/[n]rmt?
Linked device names.

 

SEE ALSO

mt(1), tar(1), cy(4)


 

Index

NAME
DESCRIPTION
FILES
SEE ALSO

This document was created by man2html, using the manual pages.
Time: 06:48:27 GMT, May 19, 2025