RECAP | ROUNDTABLE | Meeting high density demands in air-cooled environments

Inside Track’s June 23 roundtable on high-density environments quickly became a discussion of best practices for cooling IT loads of greater than 10 kilowatts (kW)/rack, as almost all the participants were supporting at least some high-density IT. As a result, the participants were able to compare notes about competing technologies and share best practices.
At the outset, a North American health care provider that its facilities had increased its use of GPUs and video to support the use of AI and analytics, which run on servers that require 3.5 kW each. To meet these new requirements, the hospital continued its use of both Hot Aisle and Cold Aisle containment strategies. Even so, the increased density, combined with virtualization, meant that the facility used less energy overall. Several operators suggested that their high-density areas also included storage and Networking servers. One operator said that short copper cable runs between two cabinets are less expensive than fiber but brought extra networking costs.
Other facility operators told shared similar stories. Most reported high- and low-density environments in close proximity, but all reported extremely tight airflow management, including scrupulous use of blanking panels and sealers to prevent “leakage,” especially in the high-density areas. Similarly, a large number of participants reported using both Hot Aisle and Cold Aisle containment in the same facility, depending on the infrastructure.
For these operators, these steps and others were considered as minimum steps. One operator noted that raising air temperatures was not a consideration because it would not free up enough power in its environment. Rather they focused on reducing stranded capacity, with a lengthy discussion about de-rating strategies. One operator routinely de-rated by 50%, with others being only slightly less aggressive.
One telecom provider said that they got manufacturers to submit power rating reports based on the expected use. These ratings were usually within 10% of actual use, but much closer than nameplate. This enabled them to avoid stranding power capacity, although he noted that his capital costs remained the same.
As a group, most of the participants say they are not yet seeing very high densities (>greater than 30 kW/rack). This group thought it might take close to a decade before these became routine. This exchange led one participant to joke that his success was due mostly to luck, although really, they tracked technologies to anticipate future IT loads and trends.