Do you still use a device with a mechanical hard drive in it? Flash storage has become so affordable and ubiquitous that it now holds the data of most of our devices outside of backup systems and NAS, SSD and flash memory. Hard drive shipments peaked in 2015, and sold less each year, but in terms of terabytes sold, hard drives are more important than ever. With web storage and backups, we stream more of our data into the cloud, and add it to AI and big data, and global server capacity is growing faster than ever before.
Accessing Flash servers, but physical hard disks still form the backbone of data farms. Larger drives have many advantages for server tors operators. Larger disks have more “array density” – how much data is stored per square inch – which can improve disk speed, and switching large disks to an existing system is always a cheaper way to increase capacity than a new server rack builder. Disk capacity continues to grow, but with the latest 16TB and 18TB drives, we’re getting closer to the limits of traditional technology.
It works like this. Hard drives store data by changing the polarity of the magnetic “bits” on the drive plate. Essentially they write data by replacing these bits so that the magnetic north points either upwards or downwards. These bits are arranged in concentric rings called “tracks”. You can increase the hard drive’s storage capacity in a number of ways: add more disks (also called “platters”), add more tracks per platter, or shorten bits (increase bits per track). There are a few problems with this though.
For one, we don’t have the space to add platters. The 18TB drive may be cramming Nine Piles enclose the standard hard drive. Adding more bits or trks also have their own problems. To make either smaller, you also need to shrink the right head. If the head is larger than tracks or bits, you may accidentally rewrite the neighboring bits when trying to write, such as trying to use a wide marker to write on narrow-lined paper.
You can shrink the right head, but this makes it difficult to create the magnetic field needed to write the data. You can tackle this by changing the material of the platter – reducing its “coercion” or how resistant it is outside the magnetic field – but this presents a new problem. On the basis of nanoparticles, as on hard drives, low-complex materials tend to flip their magnetic polarity erratically, not good if you want reliable, long-term data storage.
The solution could be microwave and heat-assisted magnetic recording, or two new technologies known as MAMR and HAMR. This uses an energy source, either a microwave generating device called a “spin-torque slayer” or a laser, or forcibly alters the platter material. This, combined with more stable platter content and smaller text heads, allows you to pack more data on each platter. Toshiba is expected to launch its first MAMR drive earlier this month, an 18TB model, and Western Digital’s MAMR drives soon. Seagate has 20 TB drives for enterprise partners, and we can also get customer versions of it.
It’s still early days with both of these technologies, but drives made with these methods (collectively called “energy-assisted magnetic recording” or EAMR), should enable drives up to 60TB and possibly beyond, such as dual-actuator designs. Add other changes that could double the speed, and hard drives should see a huge improvement over the next few years.
For more information on how HAMR and MAMR actually work, with another Western digital technology called EPMR, check out the full video, and see our list of resources here
