January 28, 2023

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Iceotope study says liquid immersion works for hard drives • The Register

Liquid cooling company Iceotope has conducted a study with Meta into the feasibility of using its technology to meet the cooling requirements of the high-density storage drives that are increasingly being deployed by hyperscale datacenter operators.

According to Iceotope, the recently published study indicates that immersion cooling offers benefits including reduced vibration and equalized temperature across a JBOD array, in addition to improved thermal management.

Rotating drives would not normally be considered for immersion-based cooling techniques as these typically call for all moving parts, such as fans, to be removed in order for a system to be completely submerged in coolant. Solid state drives (SSDs) are usually fitted instead.

However, for some customers such as hyperscale operators and high-performance computing (HPC) sites, the sheer volumes of data that they store and handle make it currently too costly to use just SSDs, and instead high-capacity hard drives are still very much in use. According to figures from storage firm Seagate, more than 90 percent of the data in cloud datacenters is held on HDDs, and the remainder on SSDs.

As the volume of data generated keeps increasing, this means more storage is needed. Disk drive makers have been adding platters and actuators (read/write heads) to deliver ever greater capacity, which translates into more power being used and therefore the heat they generate, Iceotope said.

But the introduction of helium-filled hard drives over the last decade has not only improved disk performance (helium reduces drag, cutting the energy needed to spin the platters), it means that the units are now sealed, opening the possibility of using liquid cooling with them.

Iceotope said the study looked at an air-cooled, high-density storage system that had been re-engineered to use its single-phase immersion cooling instead. It comprised two single socket nodes with two SAS expander cards, network card and a power distribution board in a 4U chassis (actually the slightly taller OpenU or OU rack unit format defined by the OCP), along with 72 hard drives.

According to Iceotope, the study demonstrates that its precision immersion cooling is a more efficient means of cooling hard drives. It said that the variation in temperature between all 72 HDDs was just 3°C, regardless of location inside the enclosure, and that the the drives could operate reliably in rack water inlet temperatures up to 40°C.

The energy required to run this system-level cooling was less than five percent of the total power consumption, it said.

Iceotope director of Innovation Neil Edmunds claimed the study demonstrates that liquid cooling for high-density storage is able to keep the drives at a lower, more consistent temperature for fewer drive failures and lower total cost of ownership.

“As demand for data storage continues to escalate, so will the solutions needed by hyperscale datacenter providers to efficiently cool the equipment,” he said in a statement.

Iceotope was one of the companies demonstrating liquid cooling tech at the recent SC22 Supercomputing Conference in Dallas. ®