- Seagate prototypes reach 7TB per platter, highest density for HDD research
- Ten-platter drives allow experimental hard drives to reach a total capacity of 70TB
- HAMR uses localized heating to write data to smaller magnetic bits
Seagate Technology has announced plans to ship a 3.5-inch hard drive with a total storage capacity of 70TB.
This follows research-grade prototypes that reached 7TB per platter, the highest areal density reported for an HDD prototype.
The company presented these results at a symposium organized by the Japan HDD Association and at a seminar organized by the National Institute of Materials Science.
Technology behind ultra-high capacity
According to Seagate, this achievement is a critical step toward reaching 10TB per platter by 2028.
The prototype units are based on a combination of heat-assisted magnetic recording (HAMR) and tile magnetic recording (SMR).
HAMR uses localized heating to write data to smaller magnetic bits, while SMR partially overlaps tracks to increase storage density.
These innovations are based on perpendicular magnetic recording (PMR), which has been used for about two decades to improve areal density, but is now reaching practical limits.
Additional support technologies include granular ferromagnets made of iron-platinum, glass substrates for dishes, and multi-sensor magnetic heads with two read heads.
Together, these innovations allow prototypes to reach densities close to 8 TB per platter, and projections suggest up to 10 TB per platter once HAMR and SMR are fully optimized.
Seagate’s development roadmap shows steady improvements in platter density over the past decade.
Capacities increased from 3TB per platter in 2018 to 6TB in 2024, driven largely by successive generations of HAMR technology.
At the same time, the increase in the number of plates in high-capacity units has contributed to overall storage growth.
Ten-platter drives are now common for experimental ultra-high-capacity HDDs, which will position them to become the largest commercially available HDDs in the late 2020s.
Combining these innovations with optimized read/write technologies also makes these drives one of the fastest HDDs currently in development.
HAMR technology has steadily increased areal density from 1.3 Tbit/square inch in 2017 to 3.7 Tbit/square inch in the first half of 2025 when combined with SMR.
Projections indicate that 10TB per platter drives are theoretically feasible within a few years.
Beyond that point, achieving 15TB per platter will require advances such as fully bit-patterned media to fully isolate the magnetic bits.
Seagate’s research indicates a realistic, though still experimental, path toward the best HDDs in terms of capacity.
While it now appears possible to get 70TB drives in late 2025 or early 2026, the timeline for commercially available 10TB per platter drives remains uncertain.
Through PC clock (originally in Japanese)
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