With density demands intensifying, actionable data on power at the rack level can be hard to come by. Marc Cram, Director of New Market Development for Legrand’s Data, Power and Control division, explains how increased visibility can create the future of PDU efficiency.
Let’s talk rack density. It used to be an issue only for major hyperscalers, but – don’t look now – it’s becoming a mainstream issue for standard data centres in traditional environments. A decade ago, power density per rack was typically about 5 kW. Now, 8.2 kW is average and almost a third of racks feature 10kW or more.
Some predict that 15 to 20 kW per rack will be the standard in the next few years. With the rise of high-performance computing and the ever-pertinent search for better ROI among tenants, increasing density presents a burgeoning challenge data centres should be preparing for. What can they do to adapt?
Leveling up, powering up
There are many considerations when optimising for rack density, weight limitations, cooling systems and containment configuration, among them. However, the most glaring element looming among these is power efficiency. If the goal is supporting something like 12 kW per rack without blowing your budget, stranded capacity and zombie servers are not an option. Optimising operational efficiency with a data centre’s most costly and essential resource – electricity – is suddenly more important than ever.
When focusing on the power efficiency of IT components, it makes sense to look at the PDU first and foremost. Rack PDUs are crucial to data centre efficiency, but traditionally PDU power assessments are completed only once, at initial installation. IT and facility managers create a power usage estimate, factor it into an operations plan and then move on to other pressing matters.
If a data centre is renovated then a second evaluation may occur, but this means years pass before rack power efficiency issues might be diagnosed – if they are ever diagnosed at all. After all, as long as a data centre avoids service downtime, why worry about power supply?
When we’re talking about efficiency, it’s not strictly about downtime. It’s about power quality even when things are up and running. Glitches, spikes, disturbances, flickers, blinks – they’re part of everyday life at a data centre. However, they’re also signs of inefficiencies to be smoothed out. To understand how to address the power sags and swells that occur in every cabinet, it’s important to first look at exactly why they happen in the first place.
Why waves matter
Unlike, say, a stove or a lamp, data centre IT equipment draws power in a non-linear way. The electrical current to the equipment comes in high-amplitude short bursts that are more like waves than a steady stream. Baked into this non-linear power load is the idea of something called harmonic distortion, inevitable disruptions in the waveform.
Harmonics cause all sorts of issues, from vibrating buzzes and overheating to voltage surges and false protective trips. Over the years, significant progress has been made to minimise harmonics with electronic devices, but it cannot be eliminated entirely.
If rack power needs to be more efficient, what can be done to fight the problems caused by harmonics? In this battleground, a data centre’s secret weapon is PDU visibility. Simply put, you can’t address a malfunctioning wave unless you can see the wave in the first place. The future of PDUs features power monitoring at the rack, enabling data centres to observe power quality continuously in real time.
Enhanced visibility into a rack’s power waveforms provides the opportunity to collect granular data, examine efficiency reporting and create automatic alerts at the PDU’s inlet, outlet and rack level. As opposed to being completely blind to a PDU’s performance, those looking for heightened functionality can gather information that can be used to predict issues caused by harmonics and prevent them before they lead to equipment inefficiencies. Let’s look at how advanced PDU monitoring can create important improvements to data centre operations.
A better way to play
Assume a disruption such as a PDU outage, device power failure, voltage dip or voltage swell has occurred. Without knowing what kind of harmonics might have caused the problem, meaningfully investigating the disruption is difficult. With enhanced PDU visibility, though, the state of the power waveform at the time of the incident is automatically captured and available for analysis immediately. Waveform captures can also be performed on-demand, for a live look-in at any given time.
Power wave performance can also be mapped over time. Knowing the total load of a cabinet at one point is helpful, but so is the ability to measure minimum and maximum load readings over a week, month or year. Making informed decisions is so much easier when a PDU’s peak performance and harmonic problems under worst-case conditions can be studied in depth. The ability to identify the processes that are causing a critical situation over time will enable data centres to prevent similar cases in the future by implementing a long-term monitoring strategy, complete with automated alerts for troubling wave forms as they emerge.
Lastly, let’s look at what happens when a circuit breaker trips. If an outlet on a PDU’s branch circuit attempts to process more amps than it can, all outlets on that circuit will shut off to protect the servers and other IT equipment. At best, this situation results in the temporary loss of a PDU.
At worst, it results in power failure for an entire cabinet. With a traditional PDU setup, a technician would need to then begin the slow and frustrating problem-solving process of locating the failed PDU and its related outlets, detach all devices on the circuit, reset the breaker and then plug the devices in one-by-one until the breaker trips again.
Compare this procedure to what would happen with advanced PDU visibility, where the individual outlet would be immediately recognised, its location identified and information on the rest of the PDU provided, without even needing to step in the room. The problem, no longer needing to be investigated, can be resolved without delay.
Foreseeable in the future
Those who want to enhance the efficiency of their systems must be aware of power quality issues and how to address them. With a smarter, more insightful PDU, tracking and analysing power performance can provide the path to optimised efficiency. So, instead of rack density threatening to derail a data centre, aspects like enhanced PDUs can make it an advantage. When it comes to power, the key to seeing into the future is to see it more clearly now.
Server Technology, a brand of Legrand, has launched the advanced PRO4X Intelligent PDU, which provides data centres with groundbreaking visibility, reporting, security and alerting. Discover more about the PRO4X PDU.
Marc Cram is Director of New Market Development for Legrand’s Data, Power and Control division, which includes the Raritan and Server Technology brands. A technology evangelist, he is driven by a passion to deliver a positive power experience for the data centre owner/operator.
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