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Seagate quietly expands multi-actuator HDD product line

Seagate has added to its multi-actuator line of Exos 2X HDDs, now offering up to 18 TB in capacity in its attempt to start paving the way for future use cases.

Seagate quietly updated its dual-actuator product page, adding two higher-capacity HDD options that can effectively double throughput at higher density.

Seagate Exos 2X Mach.2, a multi-actuator HDD, has been out in a 14 TB capacity, but this week the company also began advertising 16 TB and 18 TB models aimed at hyperscalers.

Most of the advancements in HDD technology center on increasing capacity, according to Thomas Coughlin, president of Coughlin Associates, a digital storage analysis and consulting firm. In the case of Seagate's multi-actuator HDDs, the dual-arm technology enables data transfers twice as fast as a single-arm drive. Mach.2's two new drive options allow Seagate to work out any bugs in practical applications on a smaller scale before moving multi-actuator technology to its upcoming high-capacity versions, he said.

Coughlin said Seagate is likely doing one more thing with the release of these higher-capacity HDDs: testing the waters.

"Is there a market here [for multi-actuator technology], will it grow, and are enterprise data centers and hyperscalers going to take advantage of this type of drive?" he said.

Addressing future issues

The progression from 14 TB to these two new HDD options is about laying the groundwork for what's to come rather than addressing current needs, according to Ed Burns, analyst at IDC. Seagate's Exos 2X 16 TB and 18 TB drive options likely won't draw in new customers outside of large cloud companies, he said.

Seagate Exos 2X18
Seagate increases the capacity of its Exos 2X line to 18 TB.

"It is more of a future use case. ... Once drives get to be 40 TB and above, there would be stranded capacity or capacity that cannot be quickly accessed with a single actuator," Burns said.

Multiple actuators increase throughput, but don't improve latency, so specific latency service-level agreements could still be an issue when only using multi-actuator HDDs, he said. Latency remains at 4.12 milliseconds in line with the rest of the Exos line, according to the vendor.

Coughlin added that performance increases on each drive with more than one actuator, but customers using an array of multi-actuator drives will see even more of an uptick due to aggregating throughput.

He also pointed out that as density goes up, rebuilding HDDs becomes more of a challenge due to complexity and time consumption. RAID rebuild is a matter of capacity and performance; capacity has been increasing, but performance has been roughly the same, he said.

"A dual actuator increases the data rate in and out of the drive, which will help in the instance of a drive rebuild at a high capacity," Coughlin said.

Same form factor, more performance

Seagate is offering its 16 TB and 18 TB Exos 2X Mach.2 in both SAS and SATA interface connections. The SAS version provides a maximum transfer rate of up to 554 MBps. The single-actuator versions have a maximum transfer rate of 270 MBps.

Once Seagate can establish a market, there'll be more players in the multi-actuator space.
Thomas CoughlinPresident, Coughlin Associates

Seagate stated that the 18 TB drive will act as two independent 9 TB logical units for the SAS interface and an 18 TB logical device for SATA.

Seagate offers the highest-capacity multi-actuator drives currently on the market. But it could soon be joined by Western Digital, which also has plans for multi-actuator HDDs, as well as Toshiba, which will likely enter the market as use cases emerge, Coughlin said.

"Once Seagate can establish a market, there'll be more players in the multi-actuator space," he said.

Adam Armstrong is a TechTarget Editorial news writer covering file and block storage hardware and private clouds. He previously worked at

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