Hard disk drives (HDDs), long dismissed as "relics of a bygone era" compared with solid-state drives (SSDs), are enjoying a second heyday in the age of artificial intelligence (AI). That is because they offer a lower-expense alternative for storing the explosively increasing data needed for AI training and operations. As AI corporations have begun enhancing model performance by keeping the data required for AI models rather than discarding it—and storing it on HDDs—HDDs have earned the nickname "data vault" in the AI era.
Compared with SSDs, which had been favored as storage devices for data centers, HDDs are standing out for their "price competitiveness" and "ultrahigh-capacity data storage." SSDs have clear strengths—overwhelmingly faster speeds and less noise and heat than HDDs—but as the data AI must process grows exponentially, HDDs have gained importance for their lower prices and ability to store ultrahigh-capacity data of 30 terabytes (TB) or more.
Stefan Mandl, vice president and head of global sales and marketing at Western Digital (WD), said in a written interview with ChosunBiz on the 30th, "The faster AI adoption accelerates, the more customers need high-performance storage," adding, "WD provides solutions that ensure long-term performance and durability while efficiently managing expense and energy use."
With HDD demand surging, WD is seeing steep growth in its results. WD is the leading corporation in the HDD market. It has about a 42% share, splitting the market with Seagate. WD supplies HDDs to global big tech corporations such as Google, Microsoft, Meta and Amazon.
Riding HDD demand, WD's results have entered a growth phase. In fiscal year 2025 (July 2024–June 2025), thanks to a surge in demand for high-capacity HDDs and SSDs used in AI data centers, revenue jumped 51% on-year to $9.52 billion (about 14.3656 trillion won), marking record results. WD declared this year's supply volume "sold out" and said demand for long-term contracts through 2028 has increased.
WD said it will target the market with products that maximize power efficiency while increasing storage capacity. The maximum capacity of WD products released so far is 32TB. Mandl said, "Without increasing power consumption, we will mass-produce a product in the second half of this year that expands capacity to 40TB. We aim to expand capacity to 100TB by 2029," adding, "We will help customers adopt data storage flexibly according to the roadmap." The following is a Q&A with Mandl.
— What added value can WD's HDDs create in the AI era? How is the role of HDDs changing?
"HDDs are essential for large-scale AI implementations. Training large-scale AI models with massive data requires enormous resources, so storage must not only provide high capacity reliably but also withstand long hours of intensive workloads. HDDs are suitable storage for the large-scale data center environments AI requires in terms of expense efficiency and scalability.
Market research firm IDC projects that about 80% of cloud storage will still be HDD-based in 2029. WD helps maintain long-term performance and durability reliably while efficiently managing data center operating expense and energy use."
— A significant share of revenue is concentrated in data centers and the cloud. How is your HDD business strategy being restructured?
"As we enter the AI era, it is true that customer requirements for HDDs have diversified. To operate AI data centers, you not only need the capability to safely store massive data, but also technologies that minimize power and resolve data bottlenecks.
WD focuses on five requirements when developing storage technology: capacity to handle exploding data growth; reliability to support AI stably; performance to eliminate data bottlenecks; power efficiency; and total cost of ownership (TCO) optimization for expense reduction. We have demonstrated this to customers and are pursuing collaboration through multi-year contracts.
— In the data center and cloud market, how do you differ from competitors?
"'Top capacity' and 'power efficiency.' WD is preparing the industry's highest-capacity products. We are conducting quality tests of the world's highest-capacity 40TB HDD with two customers and plan to begin mass production in the second half of this year. In 2029, we will launch a 100TB product. Beyond capacity, we also have solutions that can maximize power efficiency. WD plans to respond flexibly to the market by releasing in parallel energy-enhanced perpendicular magnetic recording (ePMR), which improves the reliability of data storage, and heat-assisted magnetic recording (HAMR) product lines that maximize storage capacity."
— What next-generation products are you preparing?
"Customers are not simply buying the drive itself. They consider comprehensively how quickly they can secure deployable capacity, whether reliability is ensured for stable operation at scale, what the power efficiency is like, and whether the price is reasonable. Because customers' AI models and applications vary, the required combinations of capacity, performance and power efficiency also differ.
To meet these customer needs quickly and flexibly, we are advancing HDD technology and expanding the HDD platform. We announced a product roadmap to customers to increase bandwidth—meaning data transfer speed—by up to eight times while introducing a power-efficiency-maximizing technology that can cut power consumption by 20% compared with existing levels. We have also built intelligent solutions so customers can quickly adopt solutions optimized for their data centers."