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Seagate uses HAMR to hit 30TB in Exos hard drives

HDD giant Seagate unveils 30TB Exos drives with higher areal density, aimed at hyperscaler customers, with products at 50TB promised for 2028 in its roadmap

Hard disk drive (HDD) capacities could double in the next few years, with a milestone achieved by Seagate that brings 30TB (terabyte) drives to the market.

This quarter, Seagate will ship the latest Exos HDDs with capacity of 30TB to cloud hyperscaler customers.

These are based on advances in areal density – capacity per disk platter area – that have now achieved 3TB per platter for the first time using heat-assisted magnetic recording (HAMR). With 10 platters per drive, that means 30TB per drive is achieved.

Seagate said it has roadmap plans to increase areal density to 4TB or 5TB in the coming years, so the prospect of nearly doubling that current 30TB capacity is possible.

What is HAMR?

HAMR HDDs are based around use of a laser in the drive write heads that temporarily heats up the platter surface to create conditions for a reliable write in the material used.

That particular ensemble of technologies forms Seagate’s Mozaic 3+ brand.

Drilling down, the core components of Mozaic 3+ are:

  • Superlattice platinum-alloy media. More areal density requires smaller grain size. The alloys used in Mozaic 3+ drives allow for the nanoscale structure and bits that are stable at such sizes.
  • Plasmonic writer technology that comprises a nanophotonic laser that can direct a very precise heat spot onto the platter surface to reliably write the data.
  • Spintronic readers that are integrated with the plasmonic write head and incorporate an extremely small and sensitive magnetic field reading sensor.
  • A system-on-a-chip controller to manage orchestration of write and read operations.

“Seagate is the world’s only hard drive manufacturer with the areal density capability to get to 3TB per platter and with 5TB on the horizon,” said Seagate CEO Dave Mosley. “As AI [artificial intelligence] use cases put a premium on raw datasets, more companies are going to need to store all the data they can. To accommodate the resulting masses of data, areal density matters more than ever.”

Will HAMR save HDDs?

Seagate’s launch of 3TB per platter drives takes hard drive capacity up to 30TB for the first time. With its proposed roadmap, capacities could reach 50TB by 2028.

Adding new and more complex components will add more cost to drives. Use of heat will likely add to cooling requirements, and that in turn adds to costs.

Those who boost the cost advantages of solid state – such as Pure Storage, which says the HDD will be obsolete by 2028 – will likely leap on such details.

But spinning disk still costs less per-gigabyte than flash in raw terms. At the end of 2023, that differential, on average, was a few cents, making flash 25% to 50% more costly per gigabyte than spinning disk.

In October 2023, flash cost averaged $0.075/GB while HDD cost averaged $0.05/GB for SAS and $0.035/GB for SATA drives.

Those prices are based on averages of HDDs and flash drives. Seagate’s Exos HDDs are targeted at hyperscalers and, they hope, sales to such customers in huge volumes will keep costs down.

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