ST(4)                       BSD Programmer's Manual                      ST(4)

NAME
     st - machine-independent SCSI tape driver

SYNOPSIS
     options SCSI
     tape st0 at tg? targetbase 0

DESCRIPTION
     The st driver for tape drives on the Small Computer System Interface (AN-
     SI X3.131-1992) bus is a machine-independent generic device which employs
     machine-dependent drivers for individual host adapters to send commands
     to manipulate tapes.  The st driver takes care of opening the tape de-
     vice, locking out other users and serializing I/O; generating the correct
     read and write Command Descriptor Blocks, and handling specialized tape
     commands such as space forward, write filemarks or rewind; detecting er-
     rors and reporting them in a standard way to the user's terminal; and
     probing for logical units on SCSI targets and classifying them according
     to their type.  The driver supports alternate tape densities on QIC
     drives by encoding the SCSI tape density in the high 5 bits of the minor
     device number.  The driver supports the standard mt(1) tape motion com-
     mands.

FILES
     /dev/rst[0-3]   auto-rewind tape devices
     /dev/nrst[0-3]  no-rewind tape devices
     /dev/rq11st0    force QIC-11 tape format
     /dev/rq150st0   force QIC-150 tape format
     /dev/rf8mm0     force fixed-length record 8mm tape format

SEE ALSO
     mt(1)

HISTORY
     Written by Donn Seeley of BSDI for BSD/386 0.3.

BUGS
     Cooked tape doesn't work.

     Many SCSI-1 tapes don't support the SCSI `mode select' command, which the
     driver uses to select tape density.  The driver currently assumes that
     most tapes do support this feature; this assumption may not be wise, and
     it will break any tape that does not support it and that isn't listed
     specifically in the driver.  Currently all Sankyo tapes and some Wangtek
     tapes are assumed not to support mode selection.

     Most SCSI-1 tapes can't report tape position.  The Archive Viper 150 sup-
     ports a read physical record number command which gives somewhat differ-
     ent results from the SCSI-2 read position command.

     The default record mode on 8mm tape is variable-length records; the spe-
     cific SCSI 8mm densities are used to select fixed-length records.  This
     is a gross hack which will go away when devt fields are widened.  For
     this reason, there isn't any way to select EXB-8200 density on an
     EXB-8500.

     The status feature of mt(1) is not very useful with SCSI tapes at this
     time.

BSDI BSD/386                    March 27, 1993                               1