How strong of a magnet do you need to erase the data on an old-fashioned tape backup system (as in, one of those things that spins around with reels and tapes)?

Can a Magnet ACTUALLY Erase Your Cassette Tape?

Would a bulk tape eraser, the kind used in radio studios to erase

A History of Removable Computer Storage

Information reel-to-reel recorder - Tapehead

Would a bulk tape eraser, the kind used in radio studios to erase

Why do the computer tape reels that you see in old movies run back

Can damaged data be retrieved from Linear Tape-Open (LTO) backup

Can I used a regular fridge magnet to erase a cassette tape? If so

Magnetic Tape - an overview

Panasonic RS-790S Reel to Reel Tape Player / Recorder TESTED *read

Can damaged data be retrieved from Linear Tape-Open (LTO) backup

Why do we use magnetic tapes to do backup? Why not use Blu-ray

Is magnetic tape storage available for the public to buy? - Quora