The current highest-capacity internal hard drive that you can buy offers 3TB of storage space, which is huge. Soon you'll be able to put even more data on one, thanks toSeagate's recent achievement in data density.

The hard-drive maker announced today that it has become the first company to achieve the milestone storage density of 1 terabit (1 trillion bits) per square inch, promising to double the current hard-drive's capacity before the end of this decade. The company says its new storage technology will also allow hard drives to reach 60TB capacity within the next decade.

Just so you know how big of a milestone this is, a square inch is about the surface of a medium-size thumb. Now imagine you can put on that tiny area the amount of bit that's much larger than the total number of stars in the Milky Way, which is estimated to be between 200 and 400 billion.

Seagate says it reached this landmark data density with a new recording technology called heat-assisted magnetic recording (HAMR). Currently, hard drives use a different recording technology called perpendicular magnetic recording (PMR), which was introduced in 2006 to replace longitudinal recording, a method dated back to the advent of hard drives for computer storage in 1956. PMR has the limit density of close to 1Tb per square inch, which is expected to be reached in the next few years.

Generally, hard-drive manufacturers increase areal density and capacity by shrinking a platter's data bits so that more bits can be put within each square inch of disk space. On top of that, they also tighten the data tracks, the concentric circles on the disk's surface that anchor the bits. The challenge to areal density gains is to do both bit shrinking and track tightening without affecting the bits' magnetization, which would garble data.



According to Seagate, HAMR technology allows for a linear bit density of about 2 million bits per inch, once thought impossible, which results in a data density of just more than 1 trillion bits, or 1 terabit, per square inch. This is about 55 percent higher than today's areal density ceiling of 620 gigabits per square inch.

Seagate says the first generation of HAMR drives will offer some 6TB of storage space in the desktop (3.5 inch) standard and 2TB in the laptop (2.5 inch) standard. Going forward, the technology also offers an unprecedented scale of capacity growth with a theoretical areal density limit ranging from 5 to 10 terabits per square inch, which translates into capacities from 30TB to 60TB for 3.5-inch drives and 10TB to 20TB for 2.5-inch drives.