Output blocksize on Fujitsu 9-track

[S. Cowles]

I've had trouble with the following operation:

    dd if=gigo of=/dev/rmt8 obs=XXk conv=sync

the computer running this is a Sun 3/280 with 4.0.3, the tape drive is a
Fujitsu 244X set at 6250bpi. For XX, the largest number I've had success
with is 63K. I'd like to use 256k but dd complains that there is an
invalid write parameter. When XX is 63 and smaller, the operation works
fine, no surprises.  64 and larger blocksizes cause the error. Anyone have
any ideas?  Thanks.

scowles at ccc.nersc.gov