Seagate confirmed that it had begun shipping its 22TB hard drives to interested parties at its recent conference call with financial analysts and investors. The new 22TB HDDs are the most capacious models on the market, using shingled magnetic recording (SMR) to enable unprecedented capacity for hyperscale data centers.
"[Our] strategy also provides manufacturing flexibility and improves our overall cost efficiencies across the breadth of our common platform family, which currently spans 16TB through 20TB capacities for CMR products, with some customers stretching to 22TB using SMR feature sets," said Dave Mosley, chief executive of Seagate, at the earnings call (via SeekingAlpha).
Seagate’s hybrid 22TB SMR hard drives are available to select customers, primarily to hyperscalers that need to maximize storage density at data centers and who have software that can take advantage of HDDs that use shingled magnetic recording technology.
Seagate’s hybrid SMR (HSMR) hard drives feature non-shingled zones (for decent random write performance) and shingled zones (for higher areal density and additional capacity). Technically, such drives leave the factory as conventional magnetic recording (CMR) HDDs and the end-user formats them in accordance with its requirements. As a result, the size of CMR and SMR bands can vary from drive to drive.
Since SMR HDDs are particularly slow when overwriting data, data center applications optimized for such drives have to write data sequentially (and preferably account for non-shingled zones used for caching) and make as few random writes or modifications as possible to maintain predictable performance.
When Seagate pre-announced its 20TB HDDs mid-2020, it said that they would use new 2.2TB perpendicular magnetic recording (PMR) platters but would rely on essentially the same platform as 16TB/18TB hard drives that use two-dimensional magnetic recording (TDMR) technology to deal with a very high track density. However, it did not explicitly say that these latest platters could be used in SMR mode for a 22TB capacity point.
This is apparently the case, so from a general hardware standpoint, Seagate's 22TB HDDs for exascalers are very similar to the Exos X20 20TB hard drives launched last month. The key difference is SMR, which adds about 10% more capacity to hit an areal density of about 1248 Gbit/inch2. Unfortunately, Seagate doesn't publish the specs for its 22TB HDDs since they might be configured differently for different clients (depending on their performance and power requirements), but some general things like maximum sustained transfer rates should be similar to the Exos X20.
As for HDDs featuring heat-assisted magnetic recording (HAMR) technology, Seagate continues to ship them to select clients for evaluations and some deployments. The company believes that HAMR will eventually move into its common platform, but hasn't said when this will happen or at which capacity point. Last year Seagate said that its technologies will enable 100TB HDDs sometime in 2030.
