Has anyone got any idea why C1504B DDS Drive (DDS-1 but
with hardware compression) should dynamically, without
any human intervention, switch off compression?

This has happened at least two times, and gets very
annoying when you mount a tape, launch a backup job,
and leave for the day, only to find it took about three
times as long as it should have, or worse still, because
of the lack of compression, halts half way through demanding
a second tape.

The only thing I can think of is that, on today's occasion,
the tape was a 60-metre Verbatim tape that had most likely
been written to before without compression.  But why should
the drive sense this and turn off compression?

Sysdiag/scsidds/modesense clearly showed compression had
been turned off.  But no human did it.  And we have been
happily writing with compression for weeks.  I guess one
solution is to put a call to devctrl.privxl.telesup (or
whatever its called) to force compression on, at the beginning
of each store job.  But isn't that a bit of a kludge?

Any clues?

Ron Burnett
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