If you can see the tape drive, the easiest way IMO is to load it up
and check the lights on the right side of the drive.

You don't have to degauss it, just load it up, use the Density
Overdride button to pick the mode you want, and write something to BOT
(bplabel would be a good choice).  I've heard rumors that even this
might not be necessary anymore, but it's guaranteed to work.

Donaldson, Mark writes:
> If I have a DLT-IV tape and it's in my library, is there a way to find
> out if it's using DLT7K densities or is maybe at some earlier format.
> Once formatted for one density, it's forever there unless degaussed,
> right?
> 
> -M 
> 
> ----------------------------------------------------------------------- 
>    Mark Donaldson - Sr. Systems Engineer 
>    Experian - Denver Colorado 
> ----------------------------------------------------------------------- 

-- 
Larry Kingery 
        Hacking's just another word for nothing left to kludge