Media is awash with stories of new data center construction worldwide. Powered by the largest cloud service providers in the world and accelerated by the growing demands of AI, these data centers measure their power demands in the scale of gigawatts (GW) and their geographical footprint can rival that of a metropolitan city.¹ These massive data centers contain incredible amounts of computing power, via GPUs, CPUs, and DRAM. But they also require massive amounts of data storage: often football-field-sized buildings full of racks containing enclosures full of hard disk drives.

The AI data center balancing act

Faced with explosive growth, data center operators are solving a complex equation of power and cost efficiency. Every watt and every dollar carry an opportunity cost. Money spent on storage is money not spent on compute; watts consumed by drives are watts unavailable to GPUs and memory. And watts are scarce.

Microsoft’s CEO recently stated that if you can’t “get the builds done fast enough close to power … you may actually have a bunch of chips sitting in inventory that I can’t plug in. In fact, that is my problem today. It’s not a supply issue of chips; it’s actually the fact that I don’t have warm shells to plug into.” Available power from utilities and having data center shells where that power exists is a critical gate to data center build-out.

The storage density challenge

Within this environment, both TCO and power efficiency have become the dominant decision drivers for HDD deployments. The critical question is simple: how much capacity can I fit into a single 3.5” HDD while maintaining efficiency and reliability?

Storage density is an essential contributor to TCO, though secondary to cost and power. These factors improve as the areal density and capacity per drive increase. Western Digital’s proven innovations in recording technologies like ePMR and OptiNAND™, and mechanical innovations such as HelioSeal®, the triple-stage actuator, and the world’s first 11-disk 3.5” HDD, have already enabled up to 26TB² capacities in a conventional recording (CMR) drives. The question now is: how do we go further?

SMR and storage capacity optimization

Enter shingled magnetic recording (SMR). This recording format—named for overlapping the data tracks on the HDD like shingles on a roof—maximizes usable capacity in a single HDD. Western Digital’s UltraSMR takes this further, applying novel data encoding and error correcting techniques to expand drive capacity up to 32TB today—a 23% gain over the 26TB CMR drive.

SMR is not a niche experiment; it’s a proven technology that enhances capacity and power efficiency, independent of future recording methods. As the industry transitions to new recording technologies like heat-assisted magnetic recording (HAMR), UltraSMR technology will continue to deliver these same advantages, helping customer achieve better TCO at scale and reduced power per terabyte.

SMR’s journey to hyperscale adoption

Historically, host-managed SMR required deep software integration and changes across the entire storage stack. The devices utilize a different command set from conventional (CMR) HDDs and have rigidly enforced rules regarding where data is allowed to be written due to the shingled architecture. This has made the ramp of SMR into the market somewhat slow.

That’s changed. Over the last 2-3 years, SMR has been deployed at massive scale by the world’s largest data center operators. These hyperscalers recognized early that SMR solved pressing TCO and power efficiency problems and had the engineering scale to integrate it. Western Digital collaborated closely with early SMR pioneers like Dropbox, whose deployment proved SMR drives could expand capacity without expanding footprint or power.

As Western Digital CEO Irving Tan stated in our earnings call following the close of FQ1’26, SMR now represents roughly 50% of our exabytes shipped into capacity-optimized data center applications. That equals a tremendous number of HDDs shipped and is a powerful proof point: SMR isn’t some future or unproven technology; it’s here today, at hyperscale.

Democratizing SMR

But the SMR story is not only the story of hyperscalers. To deliver true market impact, SMR must be accessible to enterprises and smaller-scale operators—and that transition is underway.

Western Digital’s zonedstorage.io site is a clearinghouse for tracking open-source SMR support. Through ongoing contributions, Western Digital has helped integrate native SMR compatibility into the btrfs and xfs file systems, making deployment simpler and more flexible.

Meanwhile, independent software-defined storage solutions innovators such as SaunaFS by Leil Storage, VaultFS by SwissVault, and blockOS by RedData are introducing software-defined SMR solutions that eliminate the need for custom development. Having native out-of-box solutions available to the market will expand the ability of customers to start enjoying the TCO and power efficiency advantages conferred by SMR accessible to any scale of deployment—from cloud to enterprise edge.

The storage market evolution

The demands of the modern data economy have changed. With AI and data growth surging, the industry’s focus has shifted toward TCO, power efficiency, and reliability at scale. Western Digital continues to lead through proven innovation—advancing areal density, simplifying transitions, and extending lifecycles to protect our customers’ investment.

As native SMR support matures, more customers can now take advantage of its benefits. SMR represents purposeful progress—delivering real capacity and real value today while paving the smart path to next-generation architectures like HAMR.

For storage architects and IT leaders, the takeaway is clear:

It’s time to plan for SMR as part of a modern, sustainable storage strategy—balancing capacity, cost, and continuity at every scale.

1. https://www.theguardian.com/technology/2025/jul/16/zuckerberg-meta-data-center-ai-manhattan
2. One terabyte is equal to one trillion bytes. Actual user capacity may be less due to operating environment.