[Info-vax] DLT Tape degaussing services

[William Webb]

On Fri, Mar 13, 2009 at 3:20 PM, glen herrmannsfeldt
<gah at ugcs.caltech.edu> wrote:
> Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>
>> Simply degaussing DLT tapes is not a good idea.  They have some sort of
>> "formatting" or a "clock track" that is necessary for proper operation.
>> Once degaussed, they may never work again.
>
> As I understand it, that isn't true for DLT.
> (Or at least not the current versions of DLT.)
>
> It is for Ultrium (LTO) and some others, though, so one
> should be careful before degaussing a new tape system.
>
> Also, in some cases degaussing is required.  DLT1 uses the
> same tapes as a DLT IV, but the magnetic signal is different.
> A signal left from the older drive will not get fully erased,
> and will interfere with the new data signal.
>
> According to wikipedia, the DLT formats that do use a
> servo track use an optical track on the back of the tape.
>
> -- glen
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Also, in some cases degaussing is required.  DLT1 uses the
same tapes as a DLT IV, but the magnetic signal is different.
A signal left from the older drive will not get fully erased,
and will interfere with the new data signal.

That may be true, but there are interlocks (tabs and slots) in the
side of the case that keep DLTs of various numbers (I,II,II,IV) from
working in various other DLT models.

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