This is what I got from tapetype...  after 8 hours!
Is it ok to have filemark 0 kbytes?

]# tapetype -e 20480m -f /dev/nst0
wrote 622535 32Kb blocks in 95 files in 14145 seconds (short write)
wrote 625716 32Kb blocks in 191 files in 14295 seconds (short write)
define tapetype HP-DLT-40i {
    comment "just produced by tapetype program"
    length 19503 mbytes
    filemark 0 kbytes
    speed 1404 kps
}


It seems to be working.. doing first backup now.. will try restore tomorrow 
morning.


Cheers,
Mike
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Hlade's Law:    If you have a difficult task, give it to a lazy person --
                they will find an easier way to do it.