[ams6110]

For that volume I'd think a degausser would be used.

[teraflop]

AFAIK, if you physically destroy the contents of a drive with a strong magnetic field, you also destroy the servo tracks, rendering the drive useless. Modern hard drives can't "low-level format" themselves; they're not mechanically precise enough.

[deelowe]

Degaussers render the drive nonfunctional.