Buyers' Guide
Xeon Buyer's Guide: Power struggles and the green agenda
Published: 01 Oct 2008, 06:32pm
The IT department has been taking electricity for granted - but things are changing. The power demands of IT can now outstrip the cost of the hardware, so IT managers have to balance their needs with the cost of the electricity their systems use.
"There has been a massive global rise in the cost of energy," says Intel solutions architect William Crowe. "It has become paramount that IT managers know how to make IT decisions based on power-efficiency as well as computer performance. Getting more compute capacity into a given power budget - that is where the industry is going."
The electricity bill for the IT department used to hide in the company's overall infrastructure cost. But now up to 40 per cent of a company's power budget goes on the server room, including the price of powering up and the cost of cooling servers down to keep them running efficiently.
Despite this, many companies still have their heads in the sand. But the server room turns out to be an easy place to save energy, as newer and more powerful IT equipment is entirely in line with the demand for lower power consumption. In addition, new technologies such as virtualisation are explicitly designed to use that technology more efficiently.
New quad-core Intel Xeon processor-based servers give six times the computing power of single core machines from just three years ago - and they use less energy (see the first part of our buyer’s guide computing power increases here for more on that). This means upgrading can reduce not only the number of servers but the electricity used by each one.
"Energy efficiency has been a core aspect of everything we have done from ground level up," says Crowe. "Several years ago, we had a decision to make. We could keep building single core processors and go for a frequency increase; but faster processors run hotter, and the power consumption of a device goes up exponentially as the temperature goes up."
Instead Intel made a shift towards parallel architectures and the industry is now reaping the benefits in power savings.
"Three to four years ago, power consumption was 400-500w for a two socket server," Crowe explains. "Now the power is down to 350W for a six or seven times increase in performance."
Intel makes Xeon processors in three different ranges - using different voltage levels. Modern blade servers must use lower power per processor and Intel Xeon processors built for blades go down to 50W per processor.
Virtualisation brings the power budget down too, by allowing consolidation of servers and eliminating unused capacity - a move that will have global consequences, Crowe believes.
"There are more than 30 million servers in the world, and most are below 10 per cent utilisation. If we put multiple applications on a single host, we can consolidate applications, sometimes running 10 to20 on a single box.
"A small business with 50 people on the road may have a server count of less than 30. Typically they have a complete mishmash of all sorts of servers, from two to 10 years old."
It's this unplanned equipment that can make a data centre account for up to 40 per cent of the company's total energy use and reducing that waste just means simplifying the servers.
"That company's servers can be virtualised down to just three quad-core servers, at a tiny fraction of the power usage," explains Crowe.
Measuring the problem
Saving energy, and money, has obviously become important but how can users compare and rate the different servers and green claims and choose the equipment that will really cut their power costs?
"Until recently, there has been no way to compare one server type to another," says Crowe.
Vendors have been creative with the numbers and controversial results have been published. But now there is an industry standard - SPECpower, from the Standard Performance Evaluation Corporation (SPEC).
"It's the first methodology to standardise the way the industry measures energy efficiency in a server," adds Crowe.
Announced at the end of 2007, the SPECpower benchmark ramps up a particular Java workload on a server and measures the energy consumption of the server as the load increases. The benchmark has been updated in summer 2008, and server vendors have been publishing results. So far, the vast majority of the top 25 servers are Intel Xeon processor-based.
Why the server room is the place to save
Outside the server room, energy savings can be hard to make, as light and heat are basic needs that change little. Once the company has energy efficient light bulbs and good timing systems for its heating and air-conditioning, any future efficiency moves are likely to amount to shaving a few per cent off a more-or-less fixed cost.
It's different in the data centre. Here, upgrades save power while also delivering additional benefits of extra processing power, and easier system management.
And energy saved in the server room can be saved twice over, as servers also require energy for cooling and for back-up and disaster recovery.
"For every dollar of energy you spend to power your server, you need to spend another dollar to cool that server. Roughly 50 per cent of your energy is wasted on cooling and power delivery," says Crowe.
Reducing the power demands of the server room will also reduce the amount of backup power required. This may mean the company needs a smaller generator or has to store less fuel. Or it may mean increased resilience, as the existing back-up generator can fuel the data centre for more hours.
So, newer processors use less electricity, and IT managers can deliver a greener service while moving to better technology. When you stop taking electricity for granted, everyone wins.
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