Hard drives with a capacity of 20 TB are already supplied by WDC, and in a month Seagate will also begin to supply. The former uses tiled SMR recording and ePMR to increase the recording density, while the latter will use HAMR technology with local heating of magnetic plates. The companies will be able to release HDDs of larger capacity only if they use glass plates, says Hoya, a HDD plates manufacturer.

Hoya believes that the 22 and 24 TB hard drives expected to hit the market in 2022 will be only possible if they meet who hard things. First, the number of plates should be increased to ten or more pieces. Secondly, the recording density can be significantly increased only due to the HAMR technology - by using auxiliary heating of the recording area to overcome the coercive force of the disk magnetic surface.

It was the latter technology that Seagate staked on, while Western Digital first decided to implement MAMR technology, or auxiliary microwave irradiation of the recording area, which also allows to overcome the coercive force of the magnetic layer. According to Hoya, MAMR technology is viable, but it won't push the limits of increasing storage capacity far. In principle, WDC agrees with this and is also developing its own heated recording options (HAMR).

And this is where Hoya reveals itself in all its glory. While its main competitor - Showa Denko - relies on aluminum plates, Hoya is developing the production of glass plates. Only glass will allow the production of thinner and stronger plates so that 10, 11 and 12 magnetic plates can be installed in the hard disk package, and maybe more.

As for the HAMR technology, the glass without the appearance of defects can withstand local heating up to 700 ° C, while the heat resistance of aluminum is limited to 200 ° C. The choice of the future is obvious. Increasing the capacity of hard drives over 20 TB is possible only on "glass" and this is already included in the production plans of all interested parties.