SSDs have benefited greatly from the development of 3D NAND flash memory technology, which has led to continuous growth in data density and capacity.
In comparison, the data storage density of existing HDDs has approached its technical bottleneck. HDDs are often seen to be eventually replaced by SSDs, but the large amount of data required for AI learning, coupled with new HDD data storage technologies, has extended the market lifespan of HDDs.
The key technology among all this is Seagate Technology's heat-assisted magnetic recording (HAMR) technology, which introduces laser heating to increase data storage density. It is estimated that this technology can achieve an annual data storage density growth rate of 20% for HDDs.
According to the Japanese market research institute Techno System Research (TSR), global HDD shipments reached a peak of 650 million units in 2010 but have been steadily declining since then. By 2023, it has dropped to only 19%, or 120 million units, with the 500 million units lost almost all replaced by SSDs.
HDDs still hold the advantage of having a lower capacity cost per unit compared to SSDs, especially in the nearline storage market for data centers. A report from Nikkei pointed out that in 2023, a nearline storage HDD had a unit price per GB of US$0.013, while large-capacity SSDs for servers had a unit price per GB of US$0.123, nearly 9.5 times higher than HDDs.
According to estimates by IDC, to store the learning data of generative AI, the average annual growth rate of capacity demand for data storage devices is up to 20%. Currently, the construction of each data center requires US$1 to 1.5 billion, with electricity and maintenance costs reaching US$10 to 100 million annually.
With limited funds, companies tend to prefer HDDs due to their lower storage capacity cost per unit. However, the mainstream technology for large-capacity HDDs, PMR, is only suitable for HDDs below 16TB. Even with improved technologies from major HDD manufacturers such as Western Digital (WD)'s ePMR and Toshiba's FC-MAMR, the upper limit is only 22 to 24TB with an annual data density growth rate of only 8%, which cannot meet the 20% annual capacity increase demand of data center operators.
In 2021, Toshiba proposed a new technology, MAS-MAMR, which can increase HDD's data storage cap to 30TB, an 87% increase over the mainstream 16TB HDDs used in data centers. On top of that, it significantly reduces power consumption per TB, which can greatly reduce electricity costs for data centers, thus making it suitable for upgrading existing data centers.
However, Seagate is set to begin mass production of HAMR HDDs with capacities exceeding 30TB in March 2024, with plans to produce 40TB HDDs in 2025 and introduce products that exceed 50TB between 2027 and 2028. Seagate's advancement in this technology surpasses Toshiba's MAS-MAMR, making it the hope of the HDD market in the latter half of the 2020s.
