Home / Technology / HAMR and MAMR will give us giant hard drives

HAMR and MAMR will give us giant hard drives



Are you still using a device with a mechanical hard drive in it? Flash storage has become so cheap and ubiquitous that outside backup systems and NAS, SSDs and flash memory now contain the data on most of our devices. Hard disk shipments peaked in 2015, and fewer are sold each year, but when it comes to terabyte sales, hard drives are more important than ever. With web storage and backups, we dump more of our data into the cloud, adding AI and big data, and global server capacity grows faster than ever.

Flash enters servers, but physical hard drives still form the backbone of computer farms. Larger drives have many benefits for server operators. A larger disk has a larger “area density”

; – the amount of data stored per square inch – that can improve disk speed, and replacing larger disks with an existing system is almost always a cheaper way to increase capacity than building new server racks. Disk capacity has continued to grow steadily, but with recent 16TB and 18TB drives, we are approaching the limits of conventional technology.

It works like this. Hard disks store data by changing the polarity of magnetic “bits” on the drive tray. Essentially, they write data by changing these bits so that magnetic north points either up or down. These pieces are arranged in concentric rings called “tracks”. You can increase the storage capacity of a hard disk in a few ways: Add more disks (also called “platters”), add more slots per disc, or make the bits smaller (increase the bits per slot). However, each of these has some issues.

First, we have little space to add barrels. An 18 TB drive can cram nine plates in a standard hard disk drive cover. Adding more bits or tracks also has its own problems. To make either smaller, you also need to shrink the print head. If your head is too much larger than the grooves or pieces, you may accidentally overwrite neighboring bits when trying to type, such as trying to use a giant marker to write on narrow-edged paper.

You can shrink the printhead, but this makes it more difficult to generate the magnetic field needed to write data. You can deal with this by changing the plate material – by lowering the “coercivity” or how resistant it is to magnetic fields outside – but this introduces a new problem. On the scale of nanoparticles, such as those on the hard disk, low coercivity materials tend to randomly reverse magnetic polarity, not good if you want reliable, long-term data storage.

The solution can be two new techniques called microwave and heat-assisted magnetic recording, or MAMR and HAMR. These use an energy source, either a microwave-generating unit called a “torque oscillator” or a laser, or change the coercive material of the plate material. This, combined with a more stable plate material and a smaller printhead, allows you to pack more data on each plate. Toshiba just shipped the first MAMR drive, an 18 TB model, earlier this month, and Western Digital’s MAMR drives are expected soon. Seagate has 20 TB drives for business partners, and we can also get consumer versions of them.

There are still early days with both of these pieces of technology, but drives made with these methods (collectively called “energy-assisted magnetic recording” or EAMR), should enable drives up to 60 TB and possibly beyond. Add other changes such as a dual actuator design that can double read speeds, and hard drives will see major improvements in the coming years.

For more information on how HAMR and MAMR actually work, along with another technique from Western Digital called EPMR, you can check out the full video and see our source list here


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