Despite solid state drives increasing in capacity in recent years, the humble platter-based 3.5-inch hard drive still reigns supreme as the data storage device to beat in terms of bits for your buck. But if traditional drives are going to meet user’s ever-increasing data storage demands they will need to improve on the maximum 620 gigabits per square inch storage densities currently possible in platter based 3.5-inch drives. That’s just what Seagate has demonstrated with new technology that has achieved a milestone storage density of 1 terabit per square inch.
From the advent of hard drives in 1956, the magnetic surface of the hard drive platters was divided in sub-micrometer-sized regions called magnetic domains that were oriented horizontally and parallel to the disk surface in what was called longitudinal recording. But around 2005/2006, Perpendicular Magnetic Recording (PMR) was introduced, which changed the orientation to perpendicular to allow for closer magnetic domain spacing and increase data storage capacity.
Seagate has now demonstrated a next-generation recording technology called heat-assisted magnetic recording (HAMR) that increases each platter’s storage capacity by shrinking a platter’s data bits and also tightening the concentric circles, known as data tracks, on the disk’s surface that anchor the bits.
Shrinking the data bits much further isn’t possible in current hard disk technologies because the magnetization of sufficiently small nanoparticles can randomly flip direction under the influence of temperature in what is known as superparamagnetism. HAMR technology gets around this by using materials that are stable at much smaller sizes, but which require heating with a laser before the magnetic orientation of a bit can be changed.
At the current limit of around 620 gigabits per square inch, the maximum storage capacity of today’s 3.5-inch HDDs is 3 TB, while 2.5-inch HDDs with a storage densities of around 500 gigabits per square inch top out at 750 GB. By using HAMR technology, Seagate says it has achieved a linear bit density of roughly two million bits per inch, and a data density of just over one trillion bits (1 terabit) per square inch.
Seagate anticipates that the first generation of HAMR drives will more than double the current capacities to 6 TB for 3.5-inch drives and 2 TB for 2.5-inch drives. However, with the technology offering a theoretical area density limit of somewhere from five to ten terabits per square inch, it says that 30 TB to 60 TB 3.5-inch drives and 10 TB to 20 TB 2.5-inch drives are possible in the future.
Seagate says its first HAMR hard drives will be introduced later this decade, with drives offering up to 60 TB likely to appear in the following ten years.