Despite turbulent times for the tech world, the AI boom is driving demand for mass data storage. To meet these needs, manufacturers have ambitious plans to increase hard drive capacity.
From fluctuating demand to supply chain geopolitics, the past few years have been rocky ones for the storage industry. Now, with demand for nearline storage picking back up, each of the Big Three HDD manufacturers have hit the 30TB milestone, and have ambitious plans to further ramp up hard drive capacity.
Western Digital, Seagate, and Toshiba have all laid out capacity goals for the years ahead, with hyperscalers in mind. The long-awaited mass production of HAMR drives is finally a reality, and the need to store datasets for AI training is likely to sustain demand for high-cap drives moving forward. Here’s a look at the current state of high capacity hard drives, and the factors which will shape their future.
The Great HDD Rebound
2022 and 2023 were hard years for the storage industry. HDD unit shipments almost halved in 2022, and this was followed by declines in revenue for the three largest HDD manufacturers.
However, demand has finally picked back up. From 2023 to 2024, unit volume shipments of high capacity nearline drives increased by an estimated 42%. Overall HDD shipped capacity also grew significantly, increasing by 49% to 1.32ZB over the same period.
As for the future, Wells Fargo analyst Aaron Rakers predicts that shipped HDD capacity will grow at a 19% CAGR through 2027. Analyst Tom Coughlin has a similarly sunny forecast: he projects that in 2029, HDD capacity shipments will be a stunning 7.3ZB. By that year, the lion’s share will be nearline drives, which Coughlin believes will account for over 90% of shipments, compared to 54% today.
With HDD manufacturers leaning into long-term agreements with major customers, it looks like nearline HDD will continue to be a crucial part of the storage mix.
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Onward and Upward
The recent demand fluctuation and tariff disruption haven’t discouraged the Big Three from making big plans to increase hard drive capacity. With 30TB drives in the bag, they’ve set their sights on more ambitious milestones, and are developing innovative tech to reach them.
HAMR Time: Seagate’s Mozaic 3+
Seagate was the first company to cross the 30TB finish line. Its Mozaic 3+ HDD platform incorporates 30TB+ drives making use of heat-assisted magnetic recording (HAMR). These Mozaic drives utilize superlattice platinum-alloy media, which enables smaller magnetic grains and denser recording. Seagate has also insisted that these HAMR drives are just as reliable as those using traditional perpendicular magnetic recording (PMR).
In its latest roadmap, Seagate plans to leverage HAMR to create Mozaic products with ever-greater density. The firm will ship Mozaic 4 (4TB/platter) in volume in the first half of 2026, and is aiming to have Mozaic 5 (5TB/platter) qualified in late 2027 or early 2028. If all goes well, Seagate will reach the 50+TB milestone by 2028. While ambitious, the current roadmap does mark a shift from its previous plans, which would have seen 40TB drives released in 2024-5, and 50+TB drives in 2025-6.
For years, Seagate’s promise has been that HAMR is the key to mass producing high capacity drives, which is in turn necessary if HDD is to remain the cheaper option for hyperscalers moving forward. High-cap HAMR isn’t just another milestone: the long-term existence of Seagate may depend upon its success.
Tom Coughlin, at least, is optimistic on HAMR’s prospects, and anticipates that by at least 2027, each of the big three HDD manufacturers will produce HAMR drives in volume. In the same year, he predicts more than half of HDDs will use HAMR. If this is the case, then Seagate will have earned its laurels as an early adopter of a successful technique.
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Western Digital’s UltraSMR Strategy
While Western Digital is a latecomer to HAMR, the firm has kept pace in the capacity race. In late 2024, the firm began shipping 32TB energy assisted PMR (ePMR) drives. Rather than resorting to HAMR, the milestone was achieved with an eleventh platter, and Western Digital’s pride and joy: UltraSMR.
With regular SMR (shingled magnetic recording) drives, tracks partially overlap in order to increase storage density. WD’s “UltraSMR” augments standard SMR with large block encoding and error detection algorithms to prevent noise when tracks are written closer together. With innovations like this, WD insists that it’s “on the road to 50TB by continuing to push boundaries that make leaps in capacity.”
In early 2025, WD released an updated roadmap:
At a conference, WD confirmed that they would ship HAMR drives in volume in 2027. Before this, there will be a final ePMR drive, a 36TB drive using UltraSMR. The plan is for its first HAMR drives to come in three variants: a 36TB CMR (conventional magnetic recording) drive, a 40TB SMR drive, and a 44TB UltraSMR drive.
Interestingly Western Digital is pushing its new 32TB drive as one of two new devices which are made with its new AI data cycle framework in mind. In this framework, the cycle begins and ends with data stored in high-cap HDDs. All of the data prep, ingestion, and model training happens in the intermediate stages, for which WD offers its new DC SN 655, a 64TB TLC NAND drive.
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Toshiba’s Transition
The third platter plotter, Toshiba, has a lot on its plate lately. The firm accepted a $15.3 billion offer from Japanese Industrial Partners to take the company private, was delisted in late 2023, and cut 6% of its Japanese workforce as part of a revitalization effort. Nonetheless, the firm is pushing to stay competitive in the race for hard drive capacity.
Toshiba’s primary tool for upping capacity has been its MAS-MAMR technology. That’s a variation on microwave assisted magnetic recording (MAMR), which enables a lower current in the write head, allowing for more narrowly focused recording locations. In 2024, the firm used MAMR to create a 31TB SMR demo drive with 11-platters.
However, the firm is following Seagate and WD in pursuing HAMR. By using HAMR and SMR, the firm firm achieved a 32TB 10-disk drive. It plans to ship test samples of HAMR drives this year. Looking further ahead, the firm expects to produce hard drives exceeding 40TB by 2026.
To 100TB and Beyond
With even near-term goals subject to change, long-term capacity goals can typically be taken with a grain of salt. That being said, manufacturers are thinking as far as a decade out in a bid to shape the future of magnetic storage.
Seagate expects its granular iron platinum media, which figures in its Mozaic 3 HAMR drives, to be viable at least through Mozaic 5. The same media will also likely be used in 10TB/platter drives, a milestone which Seagate CEO Dave Mosely expects will be achieved in the lab by 2028.
Beyond that, things get tricker. According to Seagate CTO Dr. John Morris, “another level of extension” of platinum media could enable 15TB platters. However, getting beyond that would require “some level of disruptive innovation”. But with multiple generations of drives between now and then, there’s ample time for a new technology to rear its head.
Both Western Digital, and Seagate, are turning their attention to bit patterned media (BPM). Heat dot magnetic recording, or HDMR, involves specially prepared media, with precisely packed patterns of bits etched within the safety of a clean room. Seagate expects BPM to enable densities in excess of 8TB per square inch, allowing for 120TB+ drives.
Uncertainty and Promise
The data storage industry has seen its share of challenges recently. But with clear roadmaps and AI-fueled demand for affordable storage at scale, the ending of the hard drive saga has clearly not yet been written.
No wonder, then, that there’s still a great deal of innovation and ambition being brought to bear on spinning media. This is especially true when it comes to the nearline drives used by hyperscalers, as manufacturers boost hard drive capacity to ensure HDD stays relevant for years to come.
At Horizon Technology, we know all about data center HDD. For practical support with managing jumps in hard drive capacity now and in the future, get in touch.
