Toshiba Looks to Turbocharge Hard Drive Capacity

The company expects MAS-MAMR technology to enable nearline HDDs of more than 30TB.

Configuration of a dual Field Generation Layer Spin Torque Oscillator (dual FGL STO) and its Oscillation Spectrum. (Image source: Toshiba.)

Configuration of a dual Field Generation Layer Spin Torque Oscillator (dual FGL STO) and its Oscillation Spectrum. (Image source: Toshiba.)

Toshiba says it has reached a milestone in magnetic recording technology. In January, the electronics company stated that it had achieved the world’s first demonstration of hard disk drive (HDD) recording performance improvement with Microwave Assisted Switching-Microwave Assisted Magnetic Recording (MAS-MAMR). The breakthrough relies on Toshiba’s bi-oscillation type spin torque oscillator device (dual FGL STO) that it showcased at the recent Joint MMM-INTERMAG Conference 2022 in January.

While there are several technical approaches to increasing the data capacity of HDDs, Toshiba contends that its MAS-MAMR method is a good candidate for achieving data capacity growth while not sacrificing data transfer rate performance, energy efficiency or reliability.

The crucial aspect of the new technology is that it delivers substantial storage capacity increases, potentially allowing nearline HDDs to reach capacities exceeding 30TB. Nearline HDDs are an intermediate option between online storage, which is immediately available, and offline storage, which is not.

Magnetic recording technology has been around since its first nascent patent in 1898. In essence, it works by magnetizing fine grains of a recording medium in one of two polarities to store a pattern of data. The polarities can be maintained for varying lengths of time depending on the materials used, but for data storage, it’s generally maintained for years. A key aspect of the technology’s performance is the distance between the magnetic read/write head and the recording medium. One way that the recording performance has improved is by decreasing the medium’s thickness and lowering the head.

The potential for 30TB of storage represents a dramatic increase over Toshiba’s 18TB MG09 hard drive, which it began shipping in 2021, and which uses a Flux Control MAMR (FC-MAMR). FC-MAMR incorporates a recording device with a nanometer-scale gap between the read/write head. It also employs spin torque oscillators to assist recording by producing microwaves that make it easier for the direction of the magnetic particles to change. During microwave irradiation, the required energy to switch polarity is reduced.

MAS-MAMR is set to improve on FC-MAMR by using a bi-oscillation type of spin torque oscillator with a two-layer field generator that produces microwaves more efficiently, with a lower current and more focus on individual recording medium particles. Although MAS-MAMR is still theoretical, Toshiba has set its sights on using it to make unprecedented improvements to recording technology.

Improving recording performance with MAS-MAMR. (Image source: Toshiba.)

Improving recording performance with MAS-MAMR. (Image source: Toshiba.)

In order to accomplish these performance enhancements, Toshiba had to address three conflicting goals. Increasing recording density requires miniaturization of the read/write head and the recording grains—that was goal one. However, this reduces the thermal stability of the recording medium, which is needed for data integrity—so goal two was to maintain thermal stability. The third goal was to tie it all together and secure sufficient recording performance.

To simultaneously increase thermal stability and recording density, a material that can better maintain magnetization must be used. The key property of such a material is coercivity, which is the degree of magnetic directional change resistance that the recording material particles possess. The microwave-assisted magnetization techniques increase the coercivity of a material, or improve how easily the magnetic direction of the particles can change, which in turn improves recording performance. The downside of higher coercivity is that it makes it more difficult for the write head to generate a magnetic field.

The key to overcoming this challenge was the introduction of an external energy source. This is where MAS-MAMR comes in with its microwaves. One way to increase density is to write data on different depths of the medium. Toshiba’s use of microwave radiation to fine-tune the polarity at different layers of the medium could greatly increase the density of data recording. However, the desired effect of MAS-MAMR on recording performance hasn’t yet been demonstrated and is still theoretical.

Toshiba’s bi-oscillation type spin torque oscillator (STO) device irradiates microwaves by means of a two-layer field generating layer (FGL). The dual FGL STO is an efficient way to generate microwaves because it uses less current while delivering on more focused spots. The idea is that when dual FGL STO is incorporated into a recording head, it improves recording performance with MAS-MAMR. Toshiba reports such an outcome for its new recording heads equipped with the STO resulting in a confirmed stable oscillation. Toshiba claims that the technology marks the first time that an approximately 6 dB improvement in recording performance with MAS-MAMR has been achieved. The next step is to test it out with HDDs with over 30TB of storage capacity.

According to Toshiba, “MAS-MAMR has taken a major step forward as a practical next-generation magnetic recording technology that can significantly improve recording density.” The company intends to commercialize nearline HDDs with over 30TB capacity equipped with MAS-MAMR. Efforts will also continue to develop FC-MAMR alongside advances in MAS-MAMR to keep amping up storage capacity. Another line of Toshiba’s R&D strategy is developing Thermal Assisted Magnetic Recording (TAMR) to deliver a wider range of storage options.

Filling the Data Demand

The advances in magnetic recording technology come at a time when expanding digital storage for data centers is a crucial aspect of many companies’ digital transformations, spurred by the COVID-19 pandemic. The growing demand for storage at the enterprise-level bodes well for nearline HDDs, which cloud computing and data centers rely on. With demand for nearline HDDs forecasted to grow by $17.5 billion by 2025, demand for more storage capacity will grow in tandem.

Such growth was in some ways unexpected. Because solid-state drive (SSD) storage is faster and more efficient than HDD, it’s the go-to option for consumer devices. However, the high-capacity of HDD storage makes it desirable for enterprise use. With the rise in remote work during the pandemic and the accompanying spur in demand for data centers’ mass storage, Forbes estimates that shipments of high-capacity HDDs grew by 50 percent in 2021 compared to 2020, which was considerably higher than analysts expected. However, it’s projected that in 2022, growth of nearline HDD shipments will decline from 50 percent to 20 percent year-over-year. HDD shipments are estimated at 234 million recording devices, down about 10 percent from 2021 shipments.

Toshiba is hardly the only innovator of data storage technology. According to a report by Digital Journal, the global next generation data storage market is expected to grow by 8.2 percent by 2028. In addition to Toshiba, some of the topic players in the data storage market include Dell EMC, IBM, HP, Western Digital, Seagate, Kingston, SanDisk, Micron Technology, Nutanix, NetApp, Quantum, Hitachi, Drobo, Avago Technologies, SimpliVity and Trintri. In other words, there’s competition to meet the mounting and diverse data storage needs, and conventional storage methods are buckling under the pressure of mounting demand from businesses, consumers and governments. Some of the top market segments include cloud-based disaster recovery, all-flash storage arrays, hybrid array, holographic data storage and Heat Assisted Magnetic Recording (HAMR).

While Toshiba is eyeing the world’s first 30TB HDD storage, Seagate’s Mach.2 Exos 2X14 is reportedly the fastest HDD at a 524MB/s sustained transfer rate (outer diameter) of 304/384 random read/write IOPS and a 4.16 ms average latency. The Mach.2 Exos 2X14 is a high-capacity dual-actuator HDD with sequential read and write performance double that of the competition. Yet, Seagate is also focused on developing HAMR, in which recording medium grains can become more densely packed while maintaining magnetic and thermal stability through a process where each bit is heated and then cooled within a nanosecond. The company also has the lofty goal of delivering 50TB hard disk drives by 2026, 100TB HDDs by 2030, and 120TB+ units by early in the next decade.

Western Digital is another prominent competitor that’s using Energy-Enhanced Perpendicular Magnetic Recording (ePMR), a technology that is somewhat similar to Toshiba’s FC-MAMR in which the write head is charged with an electric current that creates an additional magnetic field that grants greater stability.