Hopefully this will be useful to someone.

==================================================

Notes:

- the name of the AMANDA server is 'blather'

- You may (or may not) need to label the tape before
  running 'amtapetype' (I did the first time I used
  the tape).

- Rebooting causes the drive to turn HW compression back on.
  I have not found a way to turn it off that survives rebooting.
  If anyone knows of one, please let me know :)

- There is amtapetype output for this drive at the website:

  http://amanda.sourceforge.net/fom-serve/cache/453.html

  define tapetype SDLT600 {
     comment "just produced by tapetype prog (hardware compression off)"
     length 307200 mbytes
     filemark 0 kbytes
     speed 9160 kps
  }

  As you'll see below, I got the same tape size but a very different
  speed.


#
# Hardware compression turned on?
#
 root blather:/usr/local/building/amanda/tape-src
<Mon May 23 14:37>  1025 # ./amtapetype -o -c -f /dev/nst0
Writing 2048 Mbyte   compresseable data:  37 sec
Writing 2048 Mbyte uncompresseable data:  66 sec
WARNING: Tape drive has hardware compression enabled
Estimated time to write 2 * 1024 Mbyte: 66 sec = 0 h 1 min

#
# Yes -- double check with the drive
#
 root blather:/usr/local/building/amanda/tape-src
<Mon May 23 15:38>  1030 # mt -f /dev/nst0 datcompression
Compression on.
Compression capable.
Decompression capable.

#
# turn hardware compression off
#
 root blather:/usr/local/building/amanda/tape-src
<Mon May 23 15:38>  1031 # mt -f /dev/nst0 datcompression off
Compression off.
Compression capable.
Decompression capable.

#
# double check again
#
 root blather:/usr/local/building/amanda/tape-src
<Mon May 23 15:38>  1032 # mt -f /dev/nst0 datcompression
Compression off.
Compression capable.
Decompression capable.

#
# double check again with 'amtapetype -c'
#
 root blather:/usr/local/building/amanda/tape-src
<Mon May 23 15:38>  1033 # ./amtapetype -o -c -f /dev/nst0
Writing 2048 Mbyte   compresseable data:  60 sec
Writing 2048 Mbyte uncompresseable data:  60 sec
Estimated time to write 2 * 1024 Mbyte: 60 sec = 0 h 1 min

#
# now get the tape type (approx. 5.5 h actual run time)
#
 root blather:/usr/local/building/amanda/tape-src
<Mon May 23 15:56>  1037 # ./amtapetype -e 300g -t SDLT600 -f /dev/nst0
Writing 4096 Mbyte   compresseable data:  124 sec
Writing 4096 Mbyte uncompresseable data:  125 sec
Estimated time to write 2 * 307200 Mbyte: 18750 sec = 5 h 12 min
wrote 9830400 32Kb blocks in 100 files in 9564 seconds (short write)
wrote 9830400 32Kb blocks in 200 files in 9508 seconds (short write)
define tapetype SDLT600 {
   comment "just produced by tapetype prog (hardware compression off)"
   length 307200 mbytes
   filemark 0 kbytes
   speed 32988 kps
}

That's It!

--
Steve Lane
System, Network and Security Administrator
Doudna Lab
Biomolecular Structure and Mechanism Group
UC Berkeley