MAMR: The Future of Ultra-High-Capacity Hard Disk Drives

Hard drives have come a long way over the past six decades. The first hard drives were the size of refrigerators; they had record-sized platters capable of carrying a pitiful five megabytes of data. Seagate recently unveiled its upcoming twelve-terabyte model, the Seagate Barracuda Pro 12TB, a challenger to Western Digital’s twelve and fourteen-terabyte models. And Western Digital has designs on making even bigger ultra-high-capacity HDDs available to consumers by 2019—with a forty-terabyte drive available by 2025—using Microwave-Assisted Magnetic Recording, also known as MAMR.

So how does MAMR work? Why do hard drives need it? And what does MAMR mean for consumers?

To answer these questions, we have to look at two things:

  1. The problems HDD manufacturers need MAMR to solve
  2. Why previous solutions to these problems no longer prove sufficient on their own.

It’s going to be a bit of a long ride. So without further ado, let’s begin:

Why Do We Need MAMR? AKA, How Do You Increase HDD Capacity?

What do manufacturers do to squeeze every last drop of data they can into their hard drives? More or less the same way they squeezed a refrigerator-sized piece of technology and more—so, so much more—into 3.5-inch, 2.5-inch, 1.8-inch, and even smaller form factors:


Your hard drive has disk platters inside it—typically more than one—that store all of your data. Your data exists in the forms of bits made of symbolic “ones” and “zeroes,” represented by magnetically-charged regions of the disk arranged in concentric rings called tracks. To fit more data on a hard drive, the manufacturers could either add more platters or fit more ones and zeroes on a given platter surface. In fact, they do both.

But all of these methods are now falling short. When it comes to pushing the boundaries of spinning disk storage even further, hard drive manufacturers need something new. Here are just a few of the tricks HDD manufacturers have tried:

Adding More Platters

Adding more hard disk platters has its benefits. For starters, since there are more platter surfaces and more heads, data can be spread out in more locations on the drive. This has benefits to speed since the heads can read from and write to more sectors at once. In fact, it’s the same principle that makes RAID-0 arrays faster than single drives.

But adding platters obviously has some effect on the form factor of the hard drive. A two-terabyte Western Digital hard drive is a bit thicker than a 500-gigabyte drive from around the same period because, at that point in time, Western Digital was achieving this added capacity by increasing the number of platters on the drive’s spindle.

What Does Helium In Hard Drives Do?

Western Digital began making airtight hard drives filled with helium several years ago, allowing them to design platters that were thinner and could be stacked closer together for their ultra-high-capacity (i.e., 8+ terabytes) models. But you still can only pack the platters so tightly together since you need space for the stack of read/write heads to fit between them. This can obviously be problematic. Manufacturers want their hard drives to fit inside computers and servers without the need for expensive modifications.

Making Smaller Bits—Literally

Fitting more data on the platter surfaces means making the magnetic regions containing each bit smaller, thereby increasing the areal density of the platters. Manufacturers ran up against two big problems when they tried to do so.

Firstly, the smaller you make the regions, the harder it is for the heads to read and write data to them accurately. Hard drive manufacturers have attempted multiple methods to work around this problem. Secondly, when you make the regions on the platters too small, they can start to “bleed over” into each other, flipping bits and corrupting data!

Manufacturers dealt with the latter problem by switching from longitudinal recording to perpendicular recording. Perpendicular recording decreased the surface area of individual bits while keeping the bits from accidentally affecting their neighbors. It was such a breakthrough that Hitachi commissioned a video to explain the difference between the two. Manufacturers also figured out a way to overlap tracks of data, a technique known as Shingled Magnetic Recording (SMR), to improve areal density.

What about the first problem, though? Hard drive manufacturers have come up with several tricks to deal with that, and MAMR is the latest and best of those tricks.

A Closer Look at Your Read/Write Heads

There’s a limit to how small and sensitive read/write heads can be. If you’re a layperson, you might look at a stack of heads in an opened-up hard drive and say, “Those look pretty big. I bet the geniuses who build hard drives can make them smaller if they just try.”

The tip of a damaged read/write headstack
The tip of a damaged read/write headstack

But no, no, those things you’re looking at aren’t the heads. They’re the arms the read/write heads are attached to.

So you zoom in a bit. And you see these rectangular bits on the ends of the arms. You might think, “Those look pretty big. I bet the geniuses who build hard drives can make them smaller if they just try.”

The glider on the tip of a read/write head arm
The glider on the tip of a read/write head arm

But no, no, those things you’re looking at aren’t the heads, either. Those things are sliders, pieces aerodynamically designed to help the heads keep their position mere micrometers over the surfaces of the platters.

No, the real read/write heads are the minuscule copper coils you can’t even see with the naked eye. They float four to five nanometers above the platters, recording and changing the magnetic fields of individual bits. To the heads, a human hair (80,000-100,000 nanometers in diameter) might as well be Mount Everest.

That said, manufacturers pushed heads technology as much as they can. They gained finer control over the heads actuators and made smaller and more sensitive heads. But these measures could only go so far. HDD manufacturers still need to constantly fight harder and harder to keep their products relevant in an increasingly SSD-dominated world.

When All You Have Is a HAMR…

If you make the bit regions on your hard disk’s platters too small, it starts to become too hard for the heads to keep up. They require more energy to read and write data. Manufacturers’ first attempt to deal with this problem relied on using a laser built into the heads mechanism to give the read/write heads a much-needed boost. The heat from the laser would lower the energy barrier the heads needed to overcome. It’s sort of like a friend giving you a boost so you could climb a fence. This technology was known as Heat-Assisted Magnetic Recording or HAMR.

HAMR has a few problems. It was costly to implement. It was harder to manufacture. The laser that heated the platters also rendered the hard drive, in general, less reliable. And the last thing you want is an unreliable hard drive (as much as we’d make a fortune recovering data from them).

MAMR, on the other hand, uses a spin torque oscillator to generate microwave fields. The oscillator fulfills the same task as the laser, without heating the platters. The microwave oscillator is easier and cheaper to implement into headstack designs than HAMR’s laser as well. MAMR seems to essentially make HAMR useless. However, while Western Digital is pursuing MAMR, its rival Seagate seems content to stick with HAMR. Only time will tell which method comes out on top, although MAMR seems a sure winner.

MAMR: The Future of Ultra-High-Capacity Disks

So now you know how MAMR solves the problems facing manufacturers of ultra-high-capacity hard drives. But now you might be asking, “Why?”

The fact that Western Digital is pledging to use MAMR to develop forty-terabyte disks by 2025 shows their confidence in and commitment to this new technology. But you might ask yourself, “What’s the point?”

Storage manufacturers have already pushed the envelope with SSDs. Seagate developed a sixty-terabyte solid state drive. So what is this push for forty terabytes in a single hard drive about? A hard drive mid-life crisis, maybe? A desperate attempt to make hard disk drives seem more relevant as SSDs gobble up more and more of the market share and the per-gigabyte cost of NAND flash memory becomes more and more affordable?

Not quite.

With MAMR, HDDs are Still In the Game

Western Digital plans to have hard drives using MAMR available to consumers by 2019 and to have drives with up to forty terabytes of disk space by 2025. MAMR will hopefully make high-capacity hard drives cheaper. Western Digital most definitely wants to create high-capacity drives surpassing their previous 12- and 14-terabyte offerings and competitor Seagate’s Barracuda 12TB at a more welcoming price point for consumers.

But does a single hard drive really need forty terabytes of disk space?

Back in the 1980s Bill Gates allegedly said, “640 kilobytes of RAM ought to be enough for anyone.”

Gates has since denied saying it. He later said in 1999 that “no one involved in computers would ever say that.”

But the quote still holds true (whether or not it was ever actually said) as an illustration of our inability to predict what people will want in the future. After all, over a century of science-fiction literature shows that it’s quite a challenge to predict what people will want, need, and have even less than a decade from now.

A user who generates lots and lots of data—like a photographer or video editor—will jump at this opportunity. MAMR will also lead to hard drives much better suited to data centers that move around massive amounts of data all the time, as well as DVR units and surveillance systems that need room to store dozens or hundreds of hours of high-resolution video.

Rumors Of Spinning Disks’ Death Have Been Greatly Exaggerated

Don’t be so quick to write off the hard drive as dead. – Brian Gill, Gillware Data Recovery CEO

In the last three or four years or so every Tom, Dick, and Harry have proclaimed the hard disk drive as dead, or at least on its last legs. SSD is the future. It gets cheaper every year. It’s blazing fast. Every SSD innovation is a nail in the hard disk drive’s coffin.

And yet HDD manufacturers have still pushed to innovate. Hard drives have gotten bigger. And they’ve even gotten faster. Fast enough, in fact, to still be attractive over SSDs! Seagate’s Barracuda 12TB’s speed, in fact, is one of its biggest selling points currently. Hard disks are, if anything, tenacious.

The truth is that despite the doomsayers, for the foreseeable future, hard disk drives are here to stay. A forty-terabyte hard disk drive will most likely still be competitive in both performance as well as pricing, against an equivalently-massive SSD in 2025. And when you’re asking yourself whether you need that many terabytes in a single disk, blazing-fast SSD speeds are likely not your biggest concern.

Consumers who can walk into a Best Buy in 2025 and choose between a 40TB hard drive for $500 and a 60TB SSD for $1,000 (current high-capacity SSDs cost around the order of magnitude of $10,000, so this is pretty optimistic of a prediction) will go for the hard drive every time, unless they occupy a specific niche that requires lots of storage and SSD speeds.

For example, digital musicians and composers working with high-end sample libraries are often advised by the designers to, when possible, store their libraries (which often exceed 100 gigabytes) on SSDs to improve access times. But these kinds of consumers are a rare breed in a specific niche.

The hard drive is here to stay, and it seems that rather than replacing traditional spinning disks, SSDs will simply compliment them.

No one knows what the future may hold. But one thing we do know about the future is that when people lose data from their high-capacity MAMR hard drives and need their three dozen terabytes of million-megapixel photos and 8k videos salvaged, our data recovery services will still be there.

The Final Frontier

Here’s a fun little bit of serendipity: If all goes as planned, Western Digital will have its forty-terabyte HDD ready around the same time as SpaceX’s projected regular flights to Mars. What storage media do you think SpaceX will use on their rockets? Are there flash hard drives in SpaceX rockets? Or does SpaceX use traditional spinning disk drives? Western Digital’s 40TB MAMR hard disk drives? Or Seagate’s 60TB solid state drives?

We’d love to hear what you think. Leave your opinions in the comments section below.

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Will Ascenzo
Will is the lead blogger, copywriter, and copy editor for Gillware Data Recovery and Digital Forensics, and a staunch advocate against the abuse of innocent semicolons.
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