MAMR Mia – it's not just WD: Toshiba's popped to the microwave too

Oscillating microwaves reduce coercivity, permit small area bit writing

Toshiba, like Western Digital, is going to use Microwave-Assisted Magnetic Recording (MAMR) to escape the inability of current PMR tech to go beyond 15-16TB disk drive capacity.

Western Dig's MAMR is so phat, it'll store 100TB on a hard drive by 2032


Up to now we haven't known what Toshiba planned to do to increase disk capacity in the future.

PMR (Perpendicular Magnetic Recording) can be roughly thought of as groups of upright rods of magnetism in a magnetic recording medium layer, arranged in circular tracks around a disk platter. Each rod forms a bit. The end of the rod is what is magnetised by a disk's read:write head and the smaller this end area is, the less stable the applied magnetic polarity. As the bit area shrinks, the magnetic value can be altered by temperature changes or the value of neighbouring bits, rendering the disk useless.

The remedy is to use a more stable recording medium, one with a higher resistance to magnetic polarity changes, known as a high coercivity. But that coercivity has to be overcome in order for a read:write head to change the magnetic polarity.

Seagate has chosen to do thus using heat (Heat-Assisted Magnetic Recording or HAMR). Proponents of the MAMR approach say HAMR stresses the disk surface and read:write heads rendering the disk unreliable in the long-term. Seagate disputes this and has demonstrated long life HAMR read:write heads.

Western Digital has chosen MAMR for its future technology and now we know Toshiba is doing the same.

Dr Shiro Saito, a Toshiba corporate EVP, gave a presentation on Toshiba's technology strategy on November 22 and we have seen a copy of his slide deck.

Increasing nearline 3.5-inch disk drive capacity is part of that strategy and MAMR is the chosen technology:


Toshiba MAMR nearline disk drive technology. It's a pity that the timescale on the graph stops at 2018. Click to enlarge

The read:write head has an added Spin Torque Oscillator (STO) which produces microwave radiation. Microwave electro-magnetic radiation has frequencies and wavelengths between 1mm and 1m, and frequencies between 300GHz (1mm wave length) and 300MHz (1m). Microwave ovens use a 2.45GHz frequency or thereabouts and the microwave energy is absorbed by the water content in food, so heating it.

MAMR uses 20 - 40GHZ frequencies and the STO bombards a bit area with a circular AC microwave field, lowering its coercivity and enabling the bit value to be written (magnetic polarity changed as desired.)

It is reckoned that MAMR could lead to 4Tbit/in2 areal densities, beyond the 700 to 1,000Gbit/in2 used currently, and leading to 40TB drives.

Going by the chart above, we might expect Toshiba to produce a 16TB PMR disk drive in 2019 and an 18TB MAMR drive in 2020, assuming the timescale is linear. ®

Similar topics

Other stories you might like

  • EU-US Trade and Technology Council meets to coordinate on supply chains
    Agenda includes warning system for disruptions, and avoiding 'subsidy race' for chip investments

    The EU-US Trade and Technology Council (TTC) is meeting in Paris today to discuss coordinated approaches to global supply chain issues.

    This is only the second meeting of the TTC, the agenda for which was prepared in February. That highlighted a number of priorities, including securing supply chains, technological cooperation, the coordination of measures to combat distorting practices, and approaches to the decarbonization of trade.

    According to a White House pre-briefing for US reporters, the EU and US are set to announce joint approaches on technical discussions to international standard-setting bodies, an early warning system to better predict and address potential semiconductor supply chain disruptions, and a transatlantic approach to semiconductor investments aimed at ensuring security of supply.

    Continue reading
  • US cops kick back against facial recognition bans
    Plus: DeepMind launches new generalist AI system, and Apple boffin quits over return-to-work policy

    In brief Facial recognition bans passed by US cities are being overturned as law enforcement and lobbyist groups pressure local governments to tackle rising crime rates.

    In July, the state of Virginia will scrap its ban on the controversial technology after less than a year. California and New Orleans may follow suit, Reuters first reported. Vermont adjusted its bill to allow police to use facial recognition software in child sex abuse investigations.

    Elsewhere, efforts are under way in New York, Colorado, and Indiana to prevent bills banning facial recognition from passing. It's not clear if some existing vetoes set to expire, like the one in California, will be renewed. Around two dozen US state or local governments passed laws prohibiting facial recognition from 2019 to 2021. Police, however, believe the tool is useful in identifying suspects and can help solve cases especially in places where crime rates have risen.

    Continue reading
  • RISC-V needs more than an open architecture to compete
    Arm shows us that even total domination doesn't always make stupid levels of money

    Opinion Interviews with chip company CEOs are invariably enlightening. On top of the usual market-related subjects of success and failure, revenues and competition, plans and pitfalls, the highly paid victim knows that there's a large audience of unusually competent critics eager for technical details. That's you.

    Take The Register's latest interview with RISC-V International CEO Calista Redmond. It moved smartly through the gears on Intel's recent Platinum Membership of the open ISA consortium ("they're not too worried about their x86 business"), the interest from autocratic regimes (roughly "there are no rules, if some come up we'll stick by them"), and what RISC-V's 2022 will look like. Laptops. Thousand-core AI chips. Google hyperscalers. Edge. The plan seems to be to do in five years what took Arm 20.

    RISC-V may not be an existential risk to Intel, but Arm had better watch it.

    Continue reading

Biting the hand that feeds IT © 1998–2022