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
.In 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 MTWEOF0 /* 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 MTOFFL6 /* 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 MTCOMP14 /* 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_ENABLE0xffffffff
#define MT_COMP_DISABLED 0xfffffffe
#define MT_COMP_UNSUPP0xfffffffd
/*
* 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_ISVIPER10x0e /* Archive Viper-150 */
#define MT_ISPYTHON0x0f /* 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_UNIT003 /* 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
