At the moment, Toshiba offers HDDs that use two-dimensional magnetic recording (TDMR) and shingled magnetic recording (SMR). In the near-future, the Japanese firm will also introduce disks that use microwave assisted magnetic recording (MAMR), as well as heat-assisted magnetic recording (HAMR) after that.
Overall, It is not a secret that for years now Toshiba has been working on hard drives featuring SMR technology. However unlike its competitors, the company has yet to introduce any commercial SMR hard drives, so these new MAMR + SMR drives would be the first commercial SMR deployment for the company. SMR of course brings some new performance trade-offs due to the read-modify-write cycle introduced by shingled tracks, but it still makes a great deal of sense for high-capacity HDDs since it allows drive vendors to increase their capacities without switching to a new type of media.Volume production of the MAMR disks is expected in 2020. HAMR is still a bit further out as that technique requires different platter technology. Further details at AnandTech.