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What is Hard Drive Areal Density?

May 13, 2022

Areal density describes the amount of data that can be stored within a given amount of physical space on a hard drive’s platters. 

Generally speaking, a higher areal density is a good thing. Hard drives with a higher areal density usually offer more storage space, although this also depends on the number of data-storing platters within the drive’s enclosure. 

While areal density is an important metric for engineers, it’s not usually an important consideration when purchasing a hard drive for a personal computer. The areal density doesn’t necessarily determine the hard drive’s capacity — just the amount of data that can be stored on each of the platters.

Techniques for Increasing Hard Drive Areal Density

Hard drive manufacturers have worked to increase the areal density of their products for more than 70 years. Introduced in 1956, the IBM 350 had an areal density of about 2,000 bits per square inch (bit/in2). Today, some high-end server hard drives 1.1 terabytes per square inch (/in2). 

So, how are manufacturers able to hit new milestones? The answer largely depends on the purpose of the drive. For long-term storage applications, drives can make trade-offs in read/write speed in order to hold more data. For consumer-level hard drives, read/write speed and cost per gigabyte are typically more important considerations than total capacity.

For the past few decades, manufacturers have increased areal density by improving the precision of the actuator heads that read and write data. Engineers have also found ways to improve the magnetic receptivity of platters by using different materials and overcoats. 

Other techniques for improving hard drive areal density include:

Heat-Assisted Magnetic Recording (HAMR) 

Hard drives read and write data using magnetic charges. HAMR drives use read/write heads equipped with lasers, which temporarily heat up the platters and make them more receptive to magnetic effects. 

The technology was patented in 1954, but the technology wasn’t considered viable until 2006. In 2020, the first HAMR hard drives became commercially available.

Microwave-Assisted Magnetic Recording (MAMR)

 MAMR applies both microwave and magnetic fields to the hard drive platters, which generates ferromagnetic resonance. That allows the hard drive to use a lower magnetic field than is possible with conventional methods. 

Unlike HAMR, MAMR drives are expected to use about the same amount of electricity as conventional hard drives. However, HAMR will require significant research and investment — to date, no working HAMR prototypes have been produced.

Shingled Magnetic Recording 

This process essentially overlays data tracks on top of one another (hence the name — from an engineer’s perspective, the overlaid tracks are similar to roof shingles, although that’s a slight oversimplification). While shingled magnetic recording improves density, it reduces write speeds; currently, the only drives that use this technology are intended for cloud servers and other long-term storage environments.

Developing Data Recovery Techniques for High-Density Hard Drives

At, we’ve created proprietary recovery techniques for thousands of hard drive models, including many high-density drives intended for server applications.

Each new technology brings new data recovery considerations. For example, helium hard drives have become popular with enterprises for their increased areal density, reduced energy consumption, and improved durability — but when a helium hard drive fails, engineers can’t simply open the device and replace the actuator heads. To access data, the drive’s helium atmosphere must be restored, which obviously requires specialized equipment. 

By investing in advanced firmware repair tools, ISO-certified clean rooms, and in independent research and development, we’re able to offer recovery options for every type of hard drive failure. As HAMR and MAMR hard drives become commonplace, our engineers will be prepared to meet the challenge.

To discuss hard drive data recovery, contact us online or call 1-800-237-4200.