I have about 120 DLTape-VS1 tapes and 2 drives that are all near the end of their retention period, and have been superseded by newer technology. I would like to donate the whole package to my local FreeGeek organization in the hopes that someone else can get some more use out of it (many of the tapes have only been written once or twice). But first, I need a way to erase all of the tapes so that my company's data isn't leaked.
What's easiest/cheapest?
Build some sort of machine with both drives and manually blank each tape? How?
Use some sort of fancy magnet thing to passively wipe the data away?
Any other creative ways to reuse/recycle this investment in an ecologically friendly way?
You need a "degausser".
Here is one company selling them:
http://www.veritysystems.com/degaussers/erase-dlt.asp
There are probably others.
It seems there are different types for different tape drives. The one I used you just sat the tape on a small shelf and switched it on for a few seconds to erase the tape.
Fancy magnet thing (degausser). Borrow it from somebody for a day or two. Without it the process will use a lot of time and there is no guarantee your data is unrecoverable.
Confirm with one tape if you can write it after degaussing. With LTO tapes it is impossible to write them again after complete deletion, because LTO magnetic head positions itself to some already-existing guidance tracks on a tape. It cannot operate at all if they are deleted. If I remember correctly, DLT also has those tracks, but they are optical, not magnetic, so degausser will not hurt them.