Wednesday, March 30, 2016

Four Monitoring Capabilities for Data Center Power Systems

The primary method that people use to measure the energy effectiveness of their data centers is power usage effectiveness (PUE). PUE compares the power used for computing capacity and the overall power used by the data center (PUE = Total Facility Power / IT Equipment Power). The inverse of PUE is data center efficiency, according to The Green Grid association.

Currently, the industry average PUE is reported to be around 2.0, but a number of new and proven data center infrastructure technologies are available to advance efficiency and reduce PUE to 1.5 or lower without compromising availability. There are 4 key actions data center managers can take with integrating monitoring capabilities into power systems that can help improve efficiency and advance PUE.

Monitoring Power Usage

With power densities and energy costs rising, the ability to monitor energy consumption is essential for advancing PUE. Where power is measured can have an effect on how efficiency is measured.

For a comprehensive picture of data center power consumption, power should be monitored at the UPS, the room power distribution unit (PDU), and within the rack. These data points should be consolidated and reported within an enterprise data center infrastructure management (DCIM) tool that can be shared by both facilities and IT management. DCIM tools (if specified early and fully integrated) can provide an overarching view of the data center, which will provide insights into how effectively or ineffectively the computing power of the data center is being used.

Specifically, measurements taken at the UPS provide a base measurement of data center energy consumption that can be used to calculate PUE and identify energy consumption trends. Monitoring the room PDU prevents overload conditions at the PDU and helps ensure power is distributed evenly across the facility.

The best view of IT power consumption comes from intelligent PDUs inside racks, which feature integrated monitoring and control capabilities to enable continuous power monitoring and feedback to the DCIM tool. Because rack power consumption varies based on equipment within the rack and its load, each rack should be equipped with a PDU—two for dual bus environments—capable of monitoring power consumption to the rack PDU, as well as overload-protected receptacle groups and, where required, at the receptacle level.

These systems can provide PDU, branch-level, and receptacle-level monitoring of voltage, kW, current, and kWh, giving the most direct measurement of power consumption and supporting higher data center efficiency and availability.

Monitoring Rack Conditions

With increasing densities, a single rack can now support the same computing capacity that used to require an entire room. Visibility into conditions in racks can help prevent many of the most common threats to rack-based equipment, such as accidental or malicious tampering.

If specified and installed correctly, rack monitoring units can be configured to trigger alarms when rack doors are opened, water or smoke is detected, or temperature or humidity thresholds are exceeded. Many units are equipped with cameras to capture video of the event. These “eyes inside the rack” can be connected to central monitoring systems where environmental data can be integrated with power data from rack PDUs, while providing local notification by activating a beacon or other alarm if problems are detected.

Monitoring Energy Efficiency

Automating collection and analysis of data from power systems can help reduce energy consumption while increasing IT productivity. Energy efficiency monitoring can track total data center consumption, automatically calculate and analyze PUE, and optimize the use of alternative energy sources.

Using real-time data from the many support systems, the monitoring system can track and trend total infrastructure power use and compare this to capacities. For example, for UPS power output, determine when UPS units are running at peak efficiency, and report Level 1 (basic) PUE. Monitoring at the room or row PDU provides the ability to more efficiently load power supplies, dynamically manage cooling, and automatically calculate Level 2 (intermediate) PUE. Panel board monitoring provides visibility into power consumption by non-IT systems, including lighting and generators, to ensure efficient use of those systems.

Finally, rack-level monitoring provides the most accurate picture of IT equipment power consumption and can support Level 3 (advanced) PUE reporting. The ability to automate data collection, and consolidate and analyze data related to efficiency—which is one of the primary jobs of the DCIM tool—is essential to data center optimization. These functions free up data center staff to focus on strategic IT issues.

Monitoring Batteries

Batteries have long been known as a weak link in the power chain. To prevent data loss and increase uptime, most data centers specify and require a dedicated battery monitoring system, which should be installed when the data center goes online. Using a predictive battery monitoring method can provide early notification of potential battery failure. The best practice is to implement a monitoring system that connects to and tracks the health of each battery within a string.

The most effective systems continuously track all battery parameters, including internal resistance, using a dc test current to ensure measurement accuracy and repeatability. Supported by a well-defined process for preventive maintenance and replacement, monitoring batteries can significantly reduce the risk of dropped loads due to battery failure, optimize battery life, and improve safety. The use of a battery monitoring system has an excellent payback period but, more importantly, provides peace of mind to the data center operator that the power system will react and support a load during a power outage.


Previous generations of infrastructure systems were unable to adjust to dynamic load variations. UPS systems, meanwhile, operated most efficiently at full load, but full-load operation is the exception rather than the norm. The lack of flexibility in power systems led to inherent energy inefficiency.

Integrating intelligent control capabilities into data center power systems can help minimize the amount of energy being lost by enabling data center managers to tailor the performance of the UPS system to the specific efficiency and availability requirements of the site. When proper application of these capabilities is followed, it can enable double-conversion on-line UPS systems to operate at efficiency levels up to 97% while the inverter remains in operation.

Advanced UPS systems can employ an energy optimization mode that powers the load in reverse-transfer mode while keeping the UPS inverter at the ready to pick up the load in the event of a utility disturbance. An even higher degree of energy optimization provides power conditioning as well. The result is increased efficiency without compromising availability.

It is important that data center managers do not compromise on distribution and server power supply performance. Attention to distribution transformer and server power supply efficiencies can also reap huge benefits in improving PUE. Deploying TP1-rated distribution transformers can improve partial load efficiency by as much as 0.5%. High-efficiency server power supplies, while initially more expensive, can pay for themselves over their useful life.

About the Blogger

Strategic Media Asia Ltd (SMA) is one of the Approved CPD Course Providers of the Chartered Institution of Building Services Engineers (CIBSE). SMA exists to provide an interactive environment and opportunities for members of IDC industry and engineers to exchange professional views and experience on data center design, critical infrastructure system, electrical and mechanical facilities, etc.

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