Byte swapping on tape drives. (was: exabyte tape weirdness)

[Simon Cooper]

   SGI supply a number of features on their tape device drivers, the following
is from the manual entry of an ISI tape drive (see `man ts')....

      Device Specific    User Friendly        Comments
           Name              Name

     /dev/mt/ts0d0       /dev/tape       Rewind device
                                         (Standard
                                         Interface).  Bytes
                                         are swapped in
                                         order to be
                                         compatible with the
                                         IRIS 2000 and 3000
                                         workstation family.
     /dev/mt/ts0d0nr     /dev/nrtape     Non-rewinding
                                         device.  Bytes are
                                         swapped in order to
                                         be compatible with
                                         the IRIS 2000 and
                                         3000 workstation
                                         family.
     /dev/mt/ts0d0ns     /dev/tapens     Rewind device.
                                         Bytes are not
                                         swapped.
     /dev/mt/ts0d0nrns   /dev/nrtapens   Non-rewinding
                                         device.  Bytes are
                                         not swapped.

   The information about byte swapping does appear in the tps (scsi tape)
manual page but is not as obvious.  It also explains that on exabytes
/dev/tape is linked to the non-byte swapping driver for performance reasons.
I have used the IRIX 3.3.1 online manual pages to obtain this information.

Simon Cooper.