brian,

that seemed to do the trick.  even though the reference from
Dick Stone of Quantum (dlt8000linux.pdf) shows
the maximum of 49125 bpi and 67854 length... the
51000/120000 seemed to be the magic number.  Many thanks
to Chris Marble <cmarble AT odin.ac.hmc DOT edu>.

[root@mssarc test]# /sbin/dump 0udsf 51000 120000 /dev/nst0 /iarc/vol
  DUMP: Date of this level 0 dump: Mon Mar 17 10:33:25 2003
  DUMP: Dumping /dev/sda12 (/iarc/vol) to /dev/nst0
  DUMP: Label: /iarc/vol
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 25827734 tape blocks on 0.75 tape(s).
  DUMP: Volume 1 started with block 1 at: Mon Mar 17 10:34:24 2003
. . .
. . .
DUMP: Closing /dev/nst0
  DUMP: Volume 1 completed at: Mon Mar 17 12:01:32 2003
  DUMP: Volume 1 25924800 tape blocks (25317.19MB)
  DUMP: Volume 1 took 1:27:08
  DUMP: Volume 1 transfer rate: 4958 kB/s
  DUMP: 25924800 tape blocks (25317.19MB) on 1 volume(s)
  DUMP: finished in 5225 seconds, throughput 4961 kBytes/sec
  DUMP: Date of this level 0 dump: Mon Mar 17 10:33:25 2003
  DUMP: Date this dump completed:  Mon Mar 17 12:01:32 2003
  DUMP: Average transfer rate: 4958 kB/s
  DUMP: DUMP IS DONE

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