With MAMR technologies (microwave assisted magnetic recording) and HAMR (heat -assisted magnetic recording), hard drives are about to overcome the 30 TB per unit. Both technologies use an additional energy source to enable a smaller writing head, which allows a greater density of bits and tracks. But these are not the only advances in the next generation of hard drives.
Conventional perpendicular magnetic recording technology (PMR), standard on hard drives for almost two decades, has reached its limits. For this reason, manufacturers have long explored new recording technologies that expand the storage capacity of the units.
The application of microwave and laser rays has been especially promising since it reduces the intensity of the required magnetic energy and allows a weaker magnetic field to bits.
This innovation allows to reduce the size of the writing head and increase the density of writing of the bits and the data tracks, which allows to store more data on the magnetic discs and, consequently, increase the storage capacity. These technologies are known as microwave -assisted magnetic recording (MAMR) and heat -assisted magnetic recording (HAMR), depending on whether microwaves or laser rays are used.
Mamr, the starting point
Mamr hard drives are available since 2022 and, for now, represent the first stage of technology development known as MAMR Flow Control (FC-MAMR). Here, the microwave concentrate the magnetic flux in the writing head so that the magnetic energy is directed to the magnetic disk more focused.
In the next development stage, MAMR microwave-assisted switching (MAS-MAMR), microwave should also activate the magnetic material of the discs to further reduce the required magnetic energy. This involves a major technical challenge since it requires not only a new coating that responds to microwaves, but also a more precise switching of the microwave generator. In principle, with FC-MAMR this can work continuously, while with MAS-MAMR it should be activated specifically for each bit in order to prepare exactly the correct area of the magnetic surface for the writing process.
In addition, it has been shown that a microwave generator with two layers of field generation (FGL) produces less noise than one with a single FGL, which facilitates the writing and reading of bits. However, technology still requires more tests and improvement until it is reliable and profitable enough for serial production.
Mamr and Hamr technologies in the new HDD generation
Until then, FC-MAMR already allows storage capabilities greater than 30 TB per unit, thanks to the intelligent combination with two other technological improvements: a subsequent development of the staggered magnetic recording (SMR) and an eleventh magnetic disc incorporated in the hard disk housing. Toshiba recently presented a similar prototype, with a capacity of 31.24 TB.
Improvements in existing technologies
SMR technology is not new, it is a recording technology that uses overlapping data clues to increase storage density. By overwriting existing data, overlapping clues must be read and stored temporarily before writing again after the writing of the new data. Additional reading and writing operations can cause fluctuations in writing performance, which manufacturers try to compensate with better cache algorithms and larger caches.
The novelty is that larger caches can now also be used for normal reading operations, introducing more data and allowing more complex error correction mechanisms. These digital filtering algorithms come in part of radio technology, which allows you to filter the desired signals even with intense noise. In the hard disc sector they allow to compensate for a greater number of reading errors, which allows data clues to overlap more than before.
In addition, thinner magnetic discs offer an additional increase in capacity. They currently have a thickness of only 0.55 mm instead of 0.635 mm, which means that there are 11 albums instead of 10 in the standard format of 3.5 inches. Together, MAS-MAMR, SMR and the thinnest magnetic discs should increase the storage capacity of hard drives to about 40 TB in the coming years.
However, there will continue to exist units without SMR for the business sector, since many business applications generate very high writing loads and depend on a constant writing performance. SMR is not ideal for this due to long writing operations. Without SMR, business hard drives will have slightly lower capabilities.
The future belongs to Hamr
To fit into the so -called “writing space” of the writing head, the microwave generator used in MAMR must be very small, which limits its performance and makes it unlikely that the capacity can be expanded beyond the 40 TB. HAMR technology offers greater potential. In his case, a laser diode is located on the writing space, to
through which the laser beam is guided towards a nearby field transducer (NFT) via an optical fiber and concentrates on the magnetic surface. The material is heated to the point of Curie, where it loses its magnetic properties, so that the bits can align with a very low magnetic energy.
While MAMR mainly increases the linear bits density on data tracks, HAMR tends to increase track density. Like MAS-MAMR, HAMR also requires a new type of coating on magnetic discs capable of supporting precise warming and allowing a stable alignment of bits. Hamr has not yet reached Mamr’s reliability, and production processes must also be more profitable.
After all, the most important requirement in the future development of hard drives is that new technologies do not increase the price per unit of capacity; Otherwise, companies would simply resort to older and older hard drives. However, two prototypes recently presented by Toshiba show that HAMR works: one reaches 27 TB with 10 magnetic discs, and the other, in combination with SMR (and also with 10 magnetic discs), reaches 32 TB.
In conclusion, in recent years, the capacity of hard-in-law hard drives has continuously increased around 2 TB per year, while the costs have remained stable, also thanks to FC-MAMR. MAS-MAMR and HAMR must continue this development to remain in the market, where MAS-MAMR is currently closer and, therefore, the upcoming generations of hard discs of up to 30 or 40 TB will tend to use this technology. Hamr will gradually take over.
