freebsd-skq/share/man/man4/mtio.4

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.\" Copyright (c) 1996
.\" Mike Pritchard <mpp@FreeBSD.org>. All rights reserved.
.\"
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.\" @(#)mtio.4 8.1 (Berkeley) 6/5/93
.\"
.Dd February 11, 1996
.Dt MTIO 4 i386
.Os FreeBSD 2.2
.Sh NAME
.Nm mtio
.Nd
.Tn FreeBSD
magtape interface
.Sh DESCRIPTION
The special files
named
.Pa /dev/[nr]st*
refer to SCSI tape drives,
which may be attached to the system.
.Pa /dev/[nr]st*.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.
.Pp
.Pp
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
.Ql n
is usually prepended to
the name of the no-rewind devices.
.Pp
Tapes can be written with either fixed length records or variable length
records. See
.Xr st 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.
.Pp
All of the magtape devices may be manipulated with the
.Xr mt 1
command.
.Pp
A number of
.Xr ioctl 2
operations are available
on raw magnetic tape.
The following definitions are from
.Aq Pa sys/mtio.h :
.Bd -literal
/*
* 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. They are defined in the SCSI II spec */
/* and range from 0 to 0x17. 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 */
#endif
/* 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 */
daddr_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_char mt_comp0; /* compression type for mode 0 */
u_char mt_comp1; /* compression type for mode 1 */
u_char mt_comp2; /* compression type for mode 2 */
u_char mt_comp3; /* compression type for mode 3 */
#endif
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 */
#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 */
#define MTIOCIEOT _IO('m', 3) /* ignore EOT error */
#define MTIOCEEOT _IO('m', 4) /* enable EOT error */
#ifndef KERNEL
#define DEFTAPE "/dev/nrst0"
#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_ */
.Ed
.Pp
.Sh FILES
.Bl -tag -width /dev/[nr]st* -compact
.It Pa /dev/[nr]st*
.El
.Sh SEE ALSO
.Xr mt 1 ,
.Xr tar 1 ,
.Xr st 4
.Sh HISTORY
The
.Nm mtio
manual appeared in
.Bx 4.2 .
An i386 version first appeared in
.Fx 2.2 .
.Sh BUGS
The status should be returned in a device independent format.
.Pp
The special file naming should be redone in a more consistent and
understandable manner.