This may sound like a dumb question, but wouldn't it be easier to just use a bulk tape eraser (read: nicely powerful electromagnet) to completely wipe the tape and then relable it?
>To turn it off, one must use a combination of mt to run the drive, >and dd to write to it. The basic idea is to rewind the tape, use mt >to turn the compression off (see the docs on your version of mt, >they've recently been playing with it) and then write enough data >to the drive that its forced to flush its buffers. At this point >it will re-write that hidden header with the compression flags off >and that tape will then be fixed to show a no compression >preference setting when it is subsequently re-inserted nto the >drive. > >Something like this: >mt -f /dev/nst0 rewind >## save the tapes label >dd if=/dev/st0 of=./scratch bs=32k count=1 >mt -d /dev/nst0 defcompression -1 (or off, depends on your mt) >## most drives have at least a 4 meg (131072 blocks of 32768 bytes) >## buffer, so overrun it >dd if=/dev/zero of=/dev/st0 bs=32k count=131073 >## restore the label >dd if=./scratch of=/dev/st0 bs=32k count=1 >## then to show the restored label and make us feel better >dd if=/dev/st0 >##which will spit out the restored label onscreen. > >Now, if that drive has a compression status led, it should be off. >My Seagate 4 slotter has such an led in the front of the drawer.
