On Wed, Nov 07, 2007 at 01:58:42PM -0800, Andy Sparrow wrote:
> An earlier poster alluded to this phenomena.
> 
> That header information will never be overwritten by any DLT drive
> once written.
>
> And you can't access it via regular commands like mt, dd etc. to
> overwrite it either.

That's not correct for DLT.  Writing a block at BOT will change the
density for the remaining writes.  Writing to any other location on the
tape will continue using the existing density.

So a simple 'mt rewind ; dd if=/dev/zero of=<correct device> count=1'
should set the density.

See section 2.4.2 in the DLT7000 product manual
http://downloads.quantum.com/dlt7000/dlt7000productmanual.pdf

It could be that it's an old tape that has never been changed to the
correct density, but my bet is that something else is going on.

-- 
Darren Dunham                                           ddunham AT taos DOT com
Senior Technical Consultant         TAOS            http://www.taos.com/
Got some Dr Pepper?                           San Francisco, CA bay area
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