NAME

st − SCSI tape drive interface

STNOPSIS

/dev/{r|nr|ar|anr}st∗

DESCRIPTION

st is the device driver for the Small Computer System Interface (SCSI) tape drive.  The Release 3.2 or previous OS versions must use tu(4) or mt(4) depending on the drive type. In the Release 3.3 and later versions, st can handle all drive types.  There are tow types of SCSI tape drivers: the mt type and tu type.  The mt type can handle the variable length record while the tu cannot handle such records.  St supports both these types. 

St supports three standard drives: 5099EN24, 5125, and 2150S.  It is possible, however, to connect SCSI tape drives other than these.  If youspecify flags 1 to the drive in the configuration file during kernel configuration, as given below, the drive is proved as the 512-byte fixed length drive:
 

controllerstc0at iop0priority 5
tapest0st stc0 drive 0flags 1

 
If you specify flags 2 to the drive as given below, it is probed as the variable length drive:
 

tapest0st stc0 drive 0flags 2

 
Furthermore, if you specify flags 0 to the drive, St automatically investigates to which type the drive belongs.  You can check which drive type was used for probing by the configuration message displayed during the OS boot-up. 
 

stc0 at iop addr 5 intr 5
st0  at stc0 slave 0
st0: [CARTRIDGE] (512 BYTES REC)/∗ 512-byte fixed length ∗/
stc1 at iop addr 6 intr 6
st1  at stc1 slave 0
st1: [OPEN-REEL] (FLEX REC, 64K MAX)/∗ variable length record ∗/

st can handle up to four tape drives at the same time.  The lower 2 bits of the device minor number is used for specifying the device number, and bits 3 and 4 are used for specifying the record format.  However, the contents of the record formats (device minor numbers) for the four standard drive types supported by st differs depending on the drive, as given below:
 

 /dev/{r|nr|anr}st[00−03]default record format of drive
 /dev/{r|nr|anr}st[08−11]QIC−11/9 track or 1600 bpi
 /dev/{r|nr|anr}st[16−19]QIC−11/4 track or 6250 bpi
 /dev/{r|nr|anr}st[24−27]QIC−24/9 track or 3200 bpi

 
Moreover, the driver operates differently depending on the prefix indicated at the beginning of the device name.
 

 /dev/rst∗rewind a file when closing the device.
 /dev/nrst∗do not rewind a file when closing the device.
 /dev/anrst∗do not rewind a file when closing the device. auto sapce mode.

 
In the auto space mode, when the device is closed, FSF 1 is performed automatically, and the head position is reset to the beginning of the next file, as long as one or more bytes of data are actually read from the media from the time the device is opened until it is closed.

IOCTL

In addition to standard drive interface (ioctl) described in mtio(4), the st driver provides ioctl only for SCSI commands which are included in header file /sys/newsiodev/streg.h. 

Record format of the 5099EN24 drive

Two record formats, QIC−24 and QIC−11 types, are used for 5099EN24 type drives.  The device minor number (00−03) supports QIC−24 type; and the minor number (08−11) supports QIC−11. 

Record format of the 5125 drive

The 5125 drive can automatically identify and read QIC−120 and QIC−24 types.  However, only the QIC−120 type is used for writing.  Use device minor number (00−03) only. 

Record format of the 2150S drive

The 2150S type drives support QIC−24, QIC−120 and QIC−150 types.  Use device minor number (00−03) for the QIC−120 type; (08−11) for the QIC−150 type; and (16−19) for the QIC−24 type. 

FILES

/dev/{r|nr|ar|anr}st∗device special file
/dev/MAKEDEVdevice file creation shell script
/sys/newsiodev/streg.hioctl command definition

SEE ALSO

mt(1), tar(1), mtio(4), dump(8), restore(8)

DIAGNOSTICS

st∗: Error 1. Write protect is effective. 

st∗: Error 2. The specified record format is invalid.  The record format cannot be changed in the middle of the tape. 

st∗: Error 3. The request or argument of the ioctl command is invalid. 

st∗: Error 4. It encountered to the EOM during data I/O or record search. 

st∗: Error 5. Device is busy. 

The device driver also displays the error status returned by the controller as in the example given below:

st∗: SCSI error 2 on block #0.

BUG

Device names used by tu can be accessed in order to maintain compatibility with the OS versions released before version 3.2. 

St command does not support the block for a device. 

The tape will not run reverse direction using tu type drive.  Therefore, ioctl for the BSR and BSF are not supported. 

In principle, any SCSI tape drive can be operated using st.  However, this is not guaranteed. 

NEWS-OS Release 3.3