Toshiba touts industry-first 12-disk HDD stacking technology, will pair with microwave-based recording tech — says advance will enable 40TB drives in 2027

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Rival 3.5-inch HDDs are still limited to 10 or 11 platters.

Toshiba's new 12-disk stacking technology
(Image credit: Toshiba)

10/15/2025 update: The original version of this story incorrectly stated that rival drive makers currently top out at 10 platters. But Western Digital has been shipping 11-platter drives in 32TB (SMR) and 26TB (CMR) since 2024.

Toshiba has announced that it is the first company in the hard disk storage space to “verify 12-disk stacking technology.” Rivals currently aren’t able to squeeze more than 10 or 11 platters in their 3.5-inch HDDs. Thanks to this latest innovation, Toshiba expects to be able to commercialize 40TB HDDs for data centers as early as 2027.

Turn it up to 11? This one goes to 12.

How did Toshiba manage to add 20% more platters to the confines of a standard 3.5-inch form factor drive? The answer is, of course, through miniaturization. More specifically, the squishing of platters required “the development of new dedicated parts in the stack, and replacement of the current aluminum substrate medium with a glass substrate that offers greater durability and allows thinner designs.” Furthermore, Toshiba promises “improved mechanical stability and in-plane accuracy, higher density and greater reliability,” with its advanced design.

Safe from HAMR?

Toshiba is going to support the new 12-disk stacking technology devices with its Microwave-Assisted Magnetic Recording (MAMR) technology for the headlining 40TB HDDs, sometime in 2027. However, it is also investigating devices using next-generation Heat Assisted Magnetic Recording (HAMR) technology. This could be important, as its MAMR roadmap has been relatively conservative compared to rivals already on the HAMR train.

Some competitors, like Seagate, have roadmaps with 100TB+ HAMR drives (from 2030). WD is also plowing forward with HAMR, but Seagate seems to have leveraged its Invetac acquisition to put it ahead.

In summary, the 12-platter stacking breakthrough is an important engineering milestone for Toshiba. It will help prevent it from trailing too far behind rivals. Beyond capacities, Toshiba’s work is claimed to deliver “greater durability,” and that could also resonate with data center storage buyers and their TCO and reliability-focused decision-making.

More details Friday

Toshiba will be showcasing its new 12-disk stacking technology at the IDEMA Symposium on October 17, 2025, in Kawasaki, Japan. We expect to get some more technical data about its innovation there.

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Mark Tyson
Mark Tyson
News Editor

Mark Tyson is a news editor at Tom's Hardware. He enjoys covering the full breadth of PC tech; from business and semiconductor design to products approaching the edge of reason.

4 Comments Comment from the forums
  • Alvar "Miles" Udell
    They could have a cost advantage as well. If I remember correctly HAMR requires more expensive platters than MAMR.
    Reply
  • bit_user
    The article said:
    Rival 3.5-inch HDDs are still limited to 10 platters for the foreseeable future.
    I just saw a Youtube ad that claims Western Digital now has 11-platter Ultrastar drives.

    The other thought I have about these is that you get 20% longer scrub & rebuild times, when you increase platter count by 20%. At least platter density increases do something to (slightly) mitigate the ever-increasing time read/write the entire drive contents.
    Reply
  • Shiznizzle
    As long as they are not SMR, i dont care. I find that tech suspect and rewrites take time. I would rather have more drives than SMR.

    I am not sold on this heat assisted tech. Heat destroys magnetic tracks as do severe shocks.
    Reply
  • bit_user
    Shiznizzle said:
    As long as they are not SMR, i dont care. I find that tech suspect and rewrites take time. I would rather have more drives than SMR.
    Depending on what you're using it for, SMR isn't always bad. Performance-wise, I'd rather have a HDD with SMR than magnetic tape! If you're only reading & writing big files (e.g. movies), you probably wouldn't even notice the difference.

    Shiznizzle said:
    I am not sold on this heat assisted tech. Heat destroys magnetic tracks as do severe shocks.
    Server hard drives usually have a 5 year warranty. They're sold to big datacenters, some of whom buy them by the millions. I'm not saying the tech is perfect, but for them to adopt it, it's got to be pretty solid.

    The industry has been trying to make this transition for nearly a decade and it certainly seems to have taken them some time to make it work well enough. It's not some hack they just jammed in, at the last minute.
    Reply