BSD 4_3_Net_2 release
[unix-history] / usr / src / share / man / man4 / man4.tahoe / mtio.4
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.\" @(#)mtio.4 6.4 (Berkeley) 5/6/91
.\"
.Dd May 6, 1991
.Dt MTIO 4
.Os
.Sh NAME
.Nm mtio
.Nd
.Tn UNIX
magtape interface
.Sh DESCRIPTION
The special files named
.Pa /dev/cy0s ,
...,
.Pa /dev/cy15s
are interfaces to the
.Tn UNIX
magtape drivers.
For the
Tahoe, these interfaces
may be on the
.Tn VERSABUS
via a
.Tn CIPHER
tapemaster formatter
.Xr cy 4 .
The files
.Pa cy0s ,
...,
.Pa cy15s
are read/written in 25
.Tn IPS ,
The density (1600
.Tn BPI
or 3200
.Tn BPI )
is selected by a switch on the drive.
The following table of device names
applies to any of the transport/controller pairs.
.Bl -column "rewindxxx" "No-rewindxxx" "rewindxxxx" "No-rewindxxxx" -offset indent
.Em 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
.El
.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
For compatibility with customary
.Tn UNIX
tape device
names
.Dq Em mt* ,
the
.Bo Pa n Bc Pa cy*s
files are linked to appropriate
.Bo Pa n Bc Em mt*
files.
.Pp
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.
.Pp
All of the magtape devices may be manipulated with the
.Xr mt 1
command.
.Pp
A number of other
.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 */
/* 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
.Ed
.Sh FILES
.Bl -tag -width /dev/nrcy? -compact
.It Pa /dev/cy? ,
.It Pa /dev/rcy?
Rewind devices.
.It Pa /dev/ncy? ,
.It Pa /dev/nrcy?
No-rewind devices.
.It Pa /dev/[n]mt? ,
.It Pa /dev/[n]rmt?
Linked device names.
.El
.Sh SEE ALSO
.Xr mt 1 ,
.Xr tar 1 ,
.Xr cy 4