Western Digital this week outlined its near-term and mid-term plans to increase hard drive capacities to around 60TB and beyond with optimizations that significantly increase HDD performance for the AI and cloud era. In addition, the company outlined its longer-term vision for hard disk drives' evolution that includes a new laser technology for heat-assisted magnetic recording (HAMR), new platters with higher areal density, and HDD assemblies with up to 14 platters. As a result, WD will be able to offer drives beyond 140 TB in the 2030s.
(Image credit: Western Digital)
Western Digital plans to volume produce its inaugural commercial hard drives featuring HAMR technology next year, with capacities rising from 40TB (CMR) or 44TB (SMR) in late 2026, with production ramping in 2027. These drives will use the company's proven 11-platter platform with high-density media as well as HAMR heads with edge-emitting lasers that heat iron-platinum alloy (FePt) on top of platters to its Curie temperature — the point at which its magnetic properties change — and reducing its magnetic coercivity before writing data.
New lasers
These edge-emitting lasers are efficient enough to make HAMR possible, but are mechanically and optically constrained, according to Ahmed Shihab, chief product officer at Western Digital. These lasers waste part of the generated light and are physically tall. That height forces additional spacing between platters, while optical losses limit how much thermal energy can be delivered to the media — both factors directly restrict areal density scaling.
(Image credit: Western Digital)
More importantly, edge-emitting HAMR lasers are made with low yields as they rely on mechanical cleaving, precision optical alignment, and thermal screening, which prevents wafer-level testing. As a consequence, they can only be tested as part of the final head assembly, which greatly reduces yield (something that killed RDRAM years ago, as these memory chips must be tested only as part of the module assembly).
"Everybody in the industry, us included, use what is called an edge-emitting laser," Shibab said. "It is the gray box that you see sitting on the top [see the image above]. They work really well. They are the ones powering HAMR today, but they have three challenges. The light produced sometimes is wasted, so they waste a bit of energy that could be better used elsewhere. They’re quite tall, so we have to make sure the platters are some distance apart from each other. And during the hard drive manufacturing process, the yields are not as good as we’d like them to be."
To remove these limitations, Western Digital spent six years developing a patented vertical-emitting laser. Unlike conventional designs, it emits light straight down onto the magnetic media, couples more energy onto the disk, and is significantly shorter in the Z-dimension. This change enables two parallel advances: higher areal density (up from today's four terabytes per platter all the way to 10 TBs per platter) as well as a thinner head assembly that allows more disks to be packed into the same 3.5-inch drive. Furthermore, Western Digital's new vertical laser is made using a lithography process and can be tested on a wafer independently of the head, so the company also expects meaningfully higher manufacturing yields.
"By emitting more light, harnessing more of that light into the recording technology, we will increase the aerial density of the HAMR platters from four terabytes all the way to 10 terabytes by 2028 per platter," said Shihab. "This technology is not theoretical. It is actually already in the labs. We have watched it during the recording."
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