SUMMARY: Reading Solaris 2.2 DAT tapes on a HP 9000/720 workstation

From: Nicholas J Brealey (
Date: Tue Oct 26 1993 - 19:46:09 CDT

Sorry for the delay in posting the solution - the HP workstation is 120 miles
away and trying out the suggestions took some time.

After everything else had failed I called Sun Support and got the answer
in half an hour - full marks to Sun Support!

Paul Vickery from Sun Support gave me the solution:

On a Sun workstation with Solaris 2.2 use /dev/rmt/0l to write the DDS (DAT)
tape in uncompressed format.
The l option is the only one which writes uncompressed tapes - m, h and c
write compressed tapes.
The Solaris 2.2 documentation is WRONG when it says that l, m and h write
uncompressed tapes and c writes compressed tapes.


1) Solaris 2.1 can only write DDS tapes in compressed format.

2) I was trying to read the tape on a HP 6400 Series Model 2000 DDS drive
   which does not have data compression. Reading a compressed format tape
   on a workstation running HP/UX 9 with this drive crashed the workstation
   but there is a patch (from HP) to fix the problem.

3) Unlike Exabyte tapes, DDS tapes can be used in either compresssed or
   uncompressed format after they have been initialised and can even have
   a mixture of compressed and uncompressed files.

Thanks to all who replied - they all gave good suggestions
which I will consider when ever I have problems in the future.

Thanks to: (Tim) (Zdenek Dospisil) (Steve Carter) (Dan Stromberg) (Dave Cress)
kmah@DCS-Systems.COM (Kevin Mah)

Nicholas Brealey
RF Effects Department
AEA Technology
OX14 3DB

tel: +44 235 463404
fax: +44 235 463480

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