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Feature 28 December 2022 (ComputerWeekly)

With UK governments since 2010 not always prioritising energy efficiency, even reducing funding measures with full support from high-profile members of parliament, one might wonder whether the criticality of energy efficiency has been overemphasised.

Energy efficiency is crucial for driving, among other things, sustainability goals, as most cloud and datacentre services providers readily agree. However, as Tim Loake, vice-president of the infrastructure solutions group at Dell Technologies UK, says: “It [energy efficiency] is a very nuanced topic – and as soon as you think about it through different lenses, it gets more complicated.”

One issue may be that actually achieving greater energy efficiency means a move further beyond a simplistic focus on “energy efficiency” ratings and labels – for instance, on hardware.

Loake says the “easy answer” is typically that energy should equal compute load out – or “as close as you can get” – and means aligning with artificial intelligence (AI)-enablement, cooling advances including liquid cooling, and future tech innovations.

Traditionally, that sort of progress has focused on datacentre Power Usage Effectiveness (PUE) score, on which progress now appears slow.

Meanwhile, not only has power become more expensive, but total energy consumption, with the concomitant greenhouse gas emissions, depends partly on the sources of that energy, as well as all the energy that’s gone into related products and services over their entire life cycle.

“And we’ve seen, because of the spiralling energy prices, that now you’re having the time window shrink by which it makes sense to actually replace your equipment,” adds Loake.

Replacement timeframes

Previous replacement timeframes of three to five years or so no longer fit the bill. Assets become uneconomical earlier – and datacentres or providers may or may not have been able to negotiate with suppliers.

Loake has seen customers replacing kit that’s just two years old because it will slash their power bill by 40% or more. “That precipitates new issues,” he points out. “How long am I dual-running while I move my workloads from one place to another, increasing my power use while I do that.”

Then there’s rehabbing, rehoming or recycling the old kit responsibly, and the overall cost of the increased amount of kit. How much plastic is in the units, and how much embodied carbon across the whole lifecycle, and how much can be recycled or reused in a year or two? “It’s not straightforward,” he says. “Overall, I think most organisations are still driven by their profit-and-loss sheets.”

That said, Cambridge University as an HPC customer has built out a new GPU cluster, and Dell helped them turn down GPU performance by 9%: reducing power consumption by a huge 40%.

That machine is now number three in the “top 500” most energy-efficient supercomputers, says Loake.

“It’s working and thinking carefully about what you do that allows you to make these changes,” he adds. “And with our server technology, we’re always thinking about how we can save energy and also make the equipment more suitable for recycling. For example, we took the hard drive caddies and took all the plastic off of them because the plastic just made them look nice. It served no functional purpose.”

All-metal caddies can be easily melted down and remade. Equally, systems management platform sensors pinpoint hotspots and dynamically adjust the fans independently. It then becomes about how you can save energy without necessarily incurring more cost and without increasing your carbon footprint due to existing estates, says Loake.

We need better ways to compare offerings

Right now, too, many systems are labelled based on peak consumption, which might not reflect actual operating conditions, for instance. Offerings are being evolved among the Tier One suppliers for this. Dell is working on labelling the systems in better ways, which will enable customers to more easily compare apples with apples, and oranges with oranges.

“Because it’s dependent on what workload is running, how much power it needs,” says Loake. “We talk about CPU consumption as 250W a socket at peak utilisation, but very often it shouldn’t be using that unless it’s an HPC system. So, you have to think about what you are using today.”

Gisli Kr. Katrínarson (Gisli KR), chief commercial officer (CCO) of Nordic datacentre services provider atNorth, says it’s “hugely important” to differentiate between power efficiency and energy efficiency concepts. It’s also requisite to apply related thinking across entire systems, going beyond the datacentre, he says.

“Power efficiency is something we’re used to seeing broadly used by enterprises to meter what datacentre they should choose to provide them with the lowest TCO,” says Gisli. “How much electricity, now becoming more of a scarce resource, is going towards compute versus cooling? Are you reusing heat, or otherwise mitigating energy that the datacentre uses or is a waste in the datacentre?”

One atNorth datacentre in Stockholm is expected to potentially heat perhaps 20,000 nearby homes – an example of how a different understanding of energy efficiency might, taken as a whole, deliver energy and emissions savings.

Often such possibilities might not be looked at closely enough or fully understood – especially when bearing the cost of building any related infrastructure might mean a temporary competitive disadvantage.

What’s needed is industry collaboration to truly “level up” with energy efficiency, making better use of resources. “In Sweden, we are working with utility provider Exergi, where they are basically enabling companies to mitigate heat to the central heating system,” says Gisli, adding that a regional resource park has been mapping out circular economy activities.

By better understanding who is using what, productive areas for future collaboration may be teased out.

“In all respects, it makes more sense, for example, for heavy computing infrastructure to be moved closer to energy sources. Because when you move the energy to the region, you get heavy, wasteful losses of energy,” he says. “Then people get a certificate and brag about it being green – it’s utter nonsense.” ...


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