Issue link: https://www.e-digitaleditions.com/i/1386104
July/August/September 2021 I 27 core connection of equipment happens within the data center cabinet with rack power distribution units (PDUs). As a result, reliable rack PDUs within high-density environments should include, at a minimum, the following features: • Appropriate input circuit to handle required capacity • Adequate outlet type and density to plug all equipment • Branch over-current protection to minimize nuisance tripping and downtime • High ambient temperature rating for reliable operation within hot aisles • Appropriate functionality level to monitor at the rack or device • Continuous monitoring to enable proactive notification of impending issues CHALLENGE 2: MINIMIZING COOLING COSTS Reducing data center cooling costs is still a high priority among most data center operators, so addressing airflow management is key. An effective airflow management (containment) strategy allows the data center cabinet to support high-density equipment, while improving energy efficiency and lowering cooling costs. Containment systems that effectively isolate hot and cold air enable strict control of inlet temperatures, optimal adjustment of airflow volume, and increased return air temperatures, which allow room temperatures to be reliably raised. In turn, the efficiency of cooling systems is improved and the number of days that economizers can be used for "free cooling" is increased. Optimal airflow volume means fewer air handlers need to be operated, and chilled water temperatures can be increased. This yields additional chiller efficiencies, while power usage effec- tiveness (PUE) is lowered because the overall energy used for cooling equipment is reduced. In new designs in particular, initial cost can be lowered by sizing air handlers and cooling equipment for optimized airflow. Continuous and agile operations, fast and reliable processing, robust storage, and hybrid computing archi- tectures require a holistic approach, one that focuses on simplification, economization, and optimization. To get there, it is important to know what hurdles to overcome. CHALLENGE 1: RELIABLE POWER DISTRIBUTION As more data center managers and operators deploy virtualization and consolidate equipment for more efficient computing, the average rack power density continues to rise. While an average cabinet supported 3 to 4 kW just a few years ago, today that power load is considered part of a low-density environment. It is now certainly common to have cabinets drawing 9 to 15 kW and in several cases, even higher. More density means data center operators can serve more users with more compute capacity—an invaluable benefit to business operations—but it also means that heat loads within the cabinet increase (Table 1). More importantly, to handle increasing rack densities and more compute processing, reliable power needs to be assured. At the facility level, these assurances come from uninterruptible power supply (USP) systems that provide protection against blackouts and brownouts, while the DATA CENTER DENSITY Density Metric Per Rack Compute Space Extreme >= 16 kW >= 16 kW High 9 – 15 kW 9 – 15 kW Medium 5 – 8 kW 5 – 8 kW Low 0 – 4 kW 0 – 4 kW TABLE 1: Data center density definition: AFCOM's Data Center Institute's board document. Data center density is expressed as either "design density" (Per Rack) or "measured peak load divided by number of racks" (Compute Space).