Several years ago (SunOS 4.0.3) we bought a 1/2 inch SCSI tape drive to
read seismic field tapes. These tapes had physical records sized anywhere
from 100,000 bytes to 3,500,000 bytes. To get our Sparc 1+ to read those
records we had to purchase a software driver and re-make the kernal. The
source of information about the driver (an independant software provider)
said they had had no problems with record length limitations with any
hardware other than that manufactured by Sun which had a hard 64K limit
The driver was obtained from:
MicroTech Conversion Systems
940 Industrial Avenue
Palo Alto, CA 94303
This information is 3 years old. It might still be a start.
Obviously, there is no affiliation between us and MicroTech other than
we purchased something from them that solved our problem.