Fedora Users — Off-topic Onstream ADR30 tape problem

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.

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Paul (ganci@xxxxxxxxxx)