Off-topic Onstream ADR30 tape problem

["Paul R. Ganci" <ganci@xxxxxxxxxx>]

I have a very strange problem which I am hoping maybe someone else with 
an Onstream ADR50 SCSI drive may have run into and can help me. I 
purchased 12 ADR30 cartridges off Ebay. 6 of the 12 cartridges plus 8 of 
my own work just fine in the drive. The other 6 of 12 give me I/O errors 
as if they are wrtite-protected. For example the command sequence:

> mt -f /dev/nst0 rewind
>mt -f /dev/nst0 weof
/dev/nst0: Input/output error
mt: The tape is write-protected.

The log file shows the following entries in response to the "weof" 
command above:

Sep  5 19:56:18 nureyev kernel: st0: Error with sense data: Current 
st09:00: sense key Data Protect
Sep  5 19:56:18 nureyev kernel: Additional sense indicates Cannot write 
medium - incompatible format

Now before you all shout at me ... yes I checked the little tab ... the 
tapes are not physically write-protected! It is as if there was 
something recorded on these tapes which have "software write-protected" 
them. I have tried to erase them to now avail.  I always seem to get the 
message in the log file you see above. Has anyone else ever seen 
anything like this problem? I know it is the tape because I have 14 
others that work fine. Also I can't believe that 6 out of 12 tapes are 
bad ... I really think there is something on them that is preventing me 
from writing to them. If I could turn that off then I think the tapes 
will work fine.

Thanks for any help on this strange question.

--
Paul (ganci@xxxxxxxxxx)