Western Digital details 14-platter 3.5-inch HAMR HDD designs with 140 TB and beyond

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Western Digital details 14-platter 3.5-inch HAMR HDD designs with 140 TB and beyond

Western Digital doubles the performance of hard drives with dual-actuator High-Bandwidth, with path to 8X performance increase

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."

Alongside its new vertical laser technology, Western Digital is also working on an HDD platform capable of housing up to 14 platters, another part of the equation enabling the company to increase the capacity of its hard drives significantly over the next 10 years or so.

The 12-platter platform will first be used with 60TB ePMR drives in 2028. While Western Digital does not disclose how many platters the company's 60TB HAMR HDD will use, it says that its ePMR and HAMR drives will use the same platform, which suggests that HAMR products will also use generally the same design.

"We also borrowing some of the ideas from Hammer," said the CPO of Western Digital. "So, to get to 60, we will go to 12 platters. We are packing more capacity inside the same three and a half inch, all without changing the power profile of the drive. The customers don't have to spend more energy doing what we do."

Seagate achieves a whopping 6.9TB storage capacity per platter in its lab

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  1. Western Digital details 14-platter 3.5-inch HAMR HDD designs with 140 TB and beyond
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