Hi Ruben,
> 
> > > st0(bzivsc0:4:0):  Check Condition on opcode 0x1e
> > >     SENSE KEY:  Illegal Request
> > >  COMMAND INFO:  524288 (0x80000)
> > >      ASC/ASCQ:  No Additional Sense Information
> > > 
> > > 
> > > 
> > > The tape condition codes resulted from a 'mt rewind' command
> > > Any clue on this one ?
> 
> Ok. Would the tape rewind anyway?
> If not: does "echo < /dev/rst0" work? (rewind for the poor)

So, I just found the code place where this is called from.

Apparently, in the new scsi code

a) the st_mount / st_unmount calls try to block the door, if any, (indirectly)
using this opcode. Any error from this is ignored, however.
[src/sys/dev/scsipi, around line 721]

b) the new scsi code is more verbose about raw SCSI error codes, at least with
the GENERIC kernel.

I think you can savely ignore this messages, they are only logged to the 
console, the tape should rewind anyway.

	-is