On Nov 19, 2008, at 4:10 AM, Remco Post wrote:

tsm: server>del volhist todate=today t=dbb dev=drm
ANR6978E DELETE VOLHISTORY: Invalid device class UNKNOWN.

The message could be more helpful, but per the manual, DEVclass can be
used on the command only if the device class type is SERVER.

I would wait until there are more dbbackups, then let this one be of
age for a Delete Volhistory to be appropriate, rather than employ
FORCE=Yes.

   Richard Sims