tp(7) tp(7)
NAME
tp - streaming cartridge tape interface
DESCRIPTION
tp provides the interface to SCSI 1/4 inch streaming cartridge tape
drives, and uses the scsi(7) interface to communicate with the SCSI
hardware.
By default, tp uses a single SCSI target; each target may support up
to 8 cartridge tape drives (i.e., 1 drive per SCSI logical unit).
Note, however, that there are limitations on the support of multiple
logical units imposed by the scsi interface; see scsi(7) for further
details.
The binary representation of the minor device number is encoded as
tttdddmpppp. The meanings of these bits are as follows:
ttt the SCSI target id
ddd the SCSI logical unit (tape drive) number
m if set, the tape is not rewound when closed
pppp represents the recording format to be used. The formats
currently supported are:
pppp Recording
value format
0 Default mode
1 QIC-24
2 QIC-120
3 QIC-150
4-15 reserved for future use
The recording format required is communicated to the tape
hardware. When "default mode" is selected, the hardware may
determine automatically which tape format to use for read
operations. In addition, the hardware may select whether to
use QIC-120 or QIC-150 format for write operations, depending
on the type of cartridge used.
Multiple opens are not allowed, neither is opening for simultaneous
reading and writing. When a drive is opened the first time after a
cartridge is inserted, the tape is rewound if necessary. Otherwise,
the tape is not rewound when the drive is opened. When the drive is
closed, the tape will be rewound or not, depending on the state of
the m bit in the minor device number (described above). If the tape
was opened for writing, a single tape mark is written.
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tp(7) tp(7)
The following options of the MTIOCTOP ioctl (described in mtio(7))
are implemented:
MTWEOF
write a tape mark
MTFSF forward-space file
MTBSF backward-space file
MTREW rewind tape
MTOFFL
same as MTREW
MTERASE
erase the entire tape
MTEND move to the end of media
MTRET retension the tape
MTIOCTOP is the only mtio feature implemented; other commands and
behaviour described in mtio(7) are not applicable to the tp
interface.
Only a character (raw) interface is provided. This interface
provides for direct transmission between the tape drive and the
user's data area. Seeks are ignored and attempts to transfer data in
quantities that are not in multiples of 512 bytes will fail,
returning an error condition. A zero count is returned when a tape
mark is read; another read will fetch the first record of the next
tape file if there is one, otherwise a second zero count is returned.
It is unwise to continue read attempts after two consecutive zero
counts are thus returned as this indicates the extent of the valid
recorded material on the tape.
FILES
/dev/ntape
non-rewinding cartridge tape interface
/dev/tape
standard cartridge tape interface
SEE ALSO
mt(1), mtio(7), scsi(7).
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