When perpendicular magnetic recording (PMR) began to hit the buffers in terms of areal density improvements after 2010, WD subsidiary HGST began to develop helium-filled drive technology. The drives were filled with helium instead if air, and it had lower friction than air, meaning disk platters didn't need to be so strong, and could be thinner, meaning more could be fitted inside a standard drive enclosure, meaning an 80 per cent or better capacity increase. Seagate preferred to develop shingled magnetic recording as a a PMR capacity boost and look to post-PMR HAMR (heat-assisted magnetic recording) technology, then slated to arrive in 2016, as its areal density get-out-of-PMR-jail card.
https://www.theregister.co.uk/2017/04/27/seagate_missteps_as_revenue_generator_spins_down/













