As you update your legacy technologies and components for energy efficiency, introduce new hardware to cool your systems, or build new installations, remember this: Redfish®.

Why Redfish®?

When you provision your data center, you need to take the long view. Your plan should support current needs and take both future expansion and modifications into account — including the integration of components from different manufacturers.

The Redfish API was created by the DMTF (the Distributed Management Task Force) to enable the interoperability of data center components. Procuring products that support Redfish can ensure successful integration, enabling you to manage your system and its energy consumption, including thermal equipment.

Keeping Cool

As data centers process data, they generate heat. In order to function efficiently, individual electronic components need to operate within their optimal temperature ranges; this also optimizes component-level energy consumption. When temperatures rise, internal resistance rises as well; component performance can suffer while overall power consumption increases. In addition, heat must be dissipated to prevent damage to components.

According to a recent report sponsored by the U.S. Department of Energy’s Federal Energy Management Program, approximately 40% of data center energy consumption is devoted to cooling. Thermal management strategies, cooling design, and equipment selection are therefore critical in reducing power consumption and its costs — and the medium and method of cooling itself is absolutely crucial.

Some of the methods include:

• Air-based cooling: CRAC (Computer Room Air Conditioning units) and CRAH (Computer Room Air Handlers). Smaller centers often rely on these, as do some older systems.
• Liquid cooling technologies: these offer better cooling efficiency and energy savings, and are increasing in use.
  • Water-cooled centers compete with humans for the same pure, potable water that people drink. In drought-stricken Uruguay and Chile, Google’s plans to build data centers sparked protests.
  • Direct-to-Chip Cooling (Cold Plate Cooling): a highly efficient method in which coolant circulates through pipes to cold plates mounted on heat-generating components. The cold plates absorb heat into the coolant, which is then pumped away.
• Immersion cooling: heat-generating components are submerged in a tank of liquid that absorbs heat and is circulated out of the tank for cooling. This includes single-phase immersion, where the liquid remains liquid as it absorbs heat, and two-phase immersion, where the liquid boils on absorbing heat and the vapor is condensed back into a liquid. Specialized dielectric fluids are particularly effective at heat transfer.
• Rear Door Heat Exchangers (RDHX): installed on the rear door of a server rack. Hot air exits the rack and passes through the heat exchanger, where liquid coolant absorbs the heat before the air is released back into the data center.
• Hybrid cooling systems: these combine liquid cooling with air cooling to optimize the efficiency of both. Liquid cooling might, for example, handle the bulk of the heat load while air cooling manages the residual heat.

Understanding the Redfish Protocol

The Redfish protocol is a RESTful interface that provides a standardized approach to management, enables seamless integration, and offers enhanced security, scalability, and ease of use — making it ideal for modern data center environments.

The resource tree starts at the Redfish Service Root and contains all the resources used to model a rack-based Cooling Distribution Unit (CDU). Other types of cooling systems, such as immersion cooling units, follow the same model.

Cooling Units

The Redfish CoolingUnit schema supports different types of gear, such as Cooling Distribution Units (CDUs), connected through Cooling Loops that service the equipment in a single rack. Cooling Loop definitions contain product information and show the connections to and from the loop. This enables software to follow the flow of coolant through its entire cycle in a facility-level cooling system, as well as providing basic inventory functions.

PLCs — Managing Cooling Loops

PLCs can both control coolant flow and regulate temperature. PLCs typically use protocols like Modbus, Profibus, or EtherNet/IP for industrial communication. To interface with Redfish, a communication bridge or gateway is used to translate industrial protocols into Redfish-compliant RESTful commands.

The bridge allows real-time data exchange between the PLC and the data center’s IT management systems via Redfish. For instance, the PLC might report coolant temperatures, pump statuses, or alarms to the Redfish interface. As an example, an IT server can initiate an HTTP GET request to the /redfish/v1/Thermal endpoint on the PLC, and the PLC responds with a JSON payload containing thermal information.

Conclusion

Implementing the Redfish protocol for comprehensive data center monitoring offers numerous benefits — including enhanced visibility, improved energy efficiency, and secure remote management — and ensures that your data center components and controls communicate with each other to efficiently balance energy requirements.

A final word: watch for the development of PLCs that natively support Redfish — PLCs that will efficiently balance thermal management and keep your data centers cool.

Complete information regarding Redfish is available in the Redfish Data Model Specification, maintained by the DMTF. The DMTF creates open manageability standards spanning diverse emerging and traditional IT infrastructures, including cloud, virtualization, network, servers, and storage.

List of Data Center Acronyms

• ASHRAE — American Society of Heating, Refrigerating and Air-Conditioning Engineers
• CDU — cooling distribution unit
• CER — cooling efficiency ratio
• CoE — Center of Expertise
• CRAC — computer room air conditioning
• CRAH — computer room air handlers
• CUE — carbon use effectiveness
• DCEP — data center energy practitioner
• DX — direct expansion
• EMCS — energy monitoring and control system
• EPEAT — Electronic Product Environmental Assessment Tool
• ERE — energy reuse effectiveness
• ERF — energy reuse factor
• FEMP — Federal Energy Management Program
• Gflop — gigaflop
• ITEEsv — Equipment Energy Efficiency for servers
• ITEUsv — IT Equipment Utilization for servers
• MERV — minimum efficiency reporting value
• NEBS — Network Equipment Building System
• NREL — National Renewable Energy Laboratory
• PDU — power distribution unit
• PUE — power usage effectiveness
• RCI — rack cooling index
• REF — renewable energy factor
• TPU — tensor processing unit
• VSD — variable speed drive
• WUE — water use effectiveness