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Home » News » WD Bets 8x Bandwidth Beats More Terabytes as 40TB UltraSMR Starts Shipping

WD Bets 8x Bandwidth Beats More Terabytes as 40TB UltraSMR Starts Shipping

by Brian Beeler<br>on August 6, 2026

Enterprise ◇<br>HDD

Western Digital started shipping its next-generation ePMR nearline platform at up to 40TB per drive during the quarter that ended July 3, and told investors on August 5 that its 44TB HAMR drive remains on track for the first half of calendar 2027. The company shipped 231 exabytes in the quarter, 209 of which were nearline, and expects the 40TB platform to account for more than half of nearline exabytes by the third quarter of calendar 2027. That is a lot of roadmap for a single earnings call, and it comes against Seagate, which is already shipping the capacity point that WD is still qualifying.

40TB ePMR and UltraSMR, Shipping Now

The 40TB drive is not a HAMR product. It combines ePMR with UltraSMR, WD’s shingled implementation, and it is the drive the company previewed at its Innovation Day in February, when it was described as in customer qualification with volume production targeted for the second half of calendar 2026; it arrived on schedule.

Two adoption targets came with it. WD expects the 40TB platform to exceed 50% of nearline exabytes by Q3 calendar 2027, and UltraSMR across all capacities to reach roughly 60% of nearline exabyte shipments by the end of fiscal 2027. The second number is interesting. Shingled media buys capacity without new recording physics, but it does so by making track rewrites more expensive, which is why UltraSMR adoption has always been gated by how much of a hyperscaler’s fleet can tolerate the write behavior. Sixty percent of nearline exabytes would be the highest share WD has committed to publicly.

44TB HAMR: 4TB Per Platter, 11 Disks

WD’s HAMR drive reaches 44TB with 4TB per platter across an 11-disk stack, and the company’s stated design goal is that customers see performance interchangeable with ePMR so the two can be deployed side by side. Management said qualifications are progressing with positive customer feedback and reiterated the first half of calendar 2027 for shipment. Seagate reaches the same 44TB with 10 disks at roughly 4.4TB each, which means Seagate is running a higher areal density per platter, and WD is closing the gap with an extra disk in the stack.

The Path Past 44TB

WD’s published roadmap runs two capacity lines in parallel through 2032. HAMR goes 40TB in 2026, 44TB in 2027, 60TB in 2028, and 100TB in 2029 with a dotted continuation past that. ePMR runs 40TB in 2026 and 60TB in 2028, which is compelling: WD says it can take a non-HAMR recording technology to 60TB by borrowing HAMR-derived media and firmware work, moving to 14 platters, and holding power flat.

For the 100TB target, WD’s stated components are its own laser technology in place of a conventional edge-emitting laser, areal density supporting up to 10TB per platter, and a 14-disk stack. Fourteen platters at 10TB each would be 140TB, so the 100TB figure implies roughly 7.1TB per platter and leaves headroom in the stated ceiling. Whether that headroom survives contact with yield is a future WD question.

Calendar Year<br>HAMR<br>ePMR

2026<br>40TB<br>40TB (UltraSMR, shipping)

2027<br>44TB (H1)<br>n/a

2028<br>60TB<br>60TB

2029<br>100TB<br>n/a

Source: Western Digital Innovation Day, February 3, 2026, and Q4 FY2026 earnings call, August 5, 2026. Vendor-stated figures.

High Bandwidth Technology

WD said its High Bandwidth Drive technology is now sampling with five customers, offering up to 8x throughput with no corresponding increase in power. The company demonstrated 2x at Innovation Day and targets 8x by 2030.

Current nearline drives run roughly 250 to 275MB/s sustained; Seagate’s 44TB Mozaic 4+ is rated around 300MB/s. A 2x HBD drive clears 500MB/s. At 8x the theoretical range, it runs past 2,000MB/s, which puts a single spindle withing range of NVMe SSD territory for sequential work while keeping the HDD cost structure. WD frames the goal as maintaining a 6-10x cost advantage over QLC flash as capacities climb.

Sitting behind HBD on the roadmap is Dual Pivot, a second independently operating actuator set that WD says doubles transactions per second, something we’ve seen riffs on before. It is a lab technology today, with availability targeted for 2028, and it stacks with HBD.

The reason this matters more than another 4TB of capacity: AI training pipelines are increasingly bottlenecked on how fast data moves out of the capacity tier during ingestion and preparation, not on how much of it fits. Per-drive sequential bandwidth has been flat for years while capacity kept climbing, which quietly made every...