The Stack Archive Feature

The role of the UPS in data centre efficiency

Tue 8 May 2018

Data centre efficiency is an often-discussed and sometimes maligned subject. To quote Emma Fryer quoting Donald Rumsfeld – there are ‘known knowns, known unknowns and unknown unknowns.’

Not only is there a lack of reliable information, constantly differing figures, and a lot of different agendas, there are also terms and measurements that have become accepted standards, that many argue are actually unhelpful.

PUE is a useful example of this – originally intended as a yardstick to help individual data centres try to improve their efficiency, it soon became a marketing term, and is now often used to compare the respective efficiencies of data centres that are not at all comparable; a data centre in the Norwegian fjords is almost guaranteed to be more energy efficient than a sub-Saharan site – regardless of what the operators do.

And now, with a permanently and exponentially increasing level of internet usage (another issue on which wildly differing numbers are thrown around), we are going to need better data centre efficiency policies and technologies as a matter of urgency. Even with all the hardware improvements in recent years, data centre energy usage continues to career upwards.

The power of power

Data centres consume power on two main fronts: that which is required to run the equipment, and that which is required to run the air conditioning units that keep it all at the correct temperature. These are quite clearly the bread and butter of what a data centre does, and the electricity involved takes up as much as 60% of a data centre’s operating costs.

The efficiency benefits of UPS systems deserve far more recognition

This means that a data centre’s energy efficiency levels are doubly impactful – whether for better or worse. Power simply has to be consumed in order to carry out the basic operations of the data centre, and it also takes up a significant proportion of a data centre’s expenditure. It’s obvious then, that improving a data centre’s efficiency should be high up on its operators’ to-do list.

There are a number of ways to do this. The first, and perhaps most important, according to Gartner, is the need to understand the situation as it stands; that is, accurately measuring and monitoring power usage, both in the first instance and going forward.

After that (not insignificant) milestone has been passed, Gartner recommends five steps – three of which revolve around optimisation. The research house suggests optimising IT power by doing things like removing ‘zombie’ servers, consolidating VMs and increasing virtualisation. It also suggests optimising the physical space in a data centre through a modular design, and finally optimising cooling, through containment and air economisers.

The role of the UPS

As well as these pointers, Gartner gives a brief nod towards the need to update outdated UPS systems. It seems clear, though, that the efficiency benefits of UPS systems deserve far more recognition.

UPS systems have come a long way in recent years, and the rise of the modular UPS has significant implications in the data centre efficiency conversation. In previous years, UPSs had been designed in a way that favoured heavy loads. That is to say, they would be running at their most efficient when operating at loads of between 80-90%.

As well as this, because they were ‘fixed-capacity’, they would be oversized in order to achieve the necessary redundancy – they had to be sure they could match power spikes, and this meant that they were often wasting huge amounts of energy when running at lower loads – which is, in fact, the more common state of affairs.

Not only do these old-style UPS systems require more power because of the way in which they run, they also require a significant amount of cooling because of their size and workload. This made them doubly inefficient and added a significant power requirement, and in turn, cost.

How the modular UPS improves efficiency

The modular UPS, such as those produced by Riello UPS, is now coming into its own as the de-facto standard for data centres. The timing is good, too. The technology has developed roughly in line with the buying cycles of many data centres; there was a boom in data centre growth around 7-10 years ago, at which point many of the old-style, standalone UPSs were installed.

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Now many of these will need to be updated, and that means data centre operators are primed to take advantage of what modular UPSs offer. These come with a number of features that improve efficiency – the modular system itself means that rather than one standalone tower, multiple rack-mounted units can work together in parallel to match a data centre’s power requirement. A modular UPS is also transformerless, which provides a boost in efficiency of around 5%.

The key point though is the loads at which modular UPSs are most efficient. At load profiles of as low as 25%, they can operate at up to 96% efficiency. This means that they are more efficient at the loads that data centres are usually operating at – something that can’t be said for old style UPSs. In one case, the installation of a Riello modular UPS provided savings of £335,000.

What’s clear is that data centre efficiency should be a hot topic for anyone in this space. For those looking for a pragmatic, practical reason, the cost savings should provide ample motivation. For those thinking a little more long-term, when we consider the ever-growing boom in internet usage and where data centre power currently sits worldwide, it’s obvious that it’s for the betterment of everyone if we can make data centres the best they can possibly be.

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