Crunching the numbers on data-centre efficiency

Tangible metrics on server performance can help cut through some of the greenwash around sustainable IT, but they can prove difficult to acquire

From carbon-neutral search engines to energy-efficient power supplies, we're surrounded by products that promise to increase energy efficiency and reduce our carbon footprint. But, while there are a lot of marketing budgets being thrown at the issue, there appears to be little real enthusiasm for sustainability in IT departments.

"The problem is that most IT managers simply aren't that interested in being green," said Mick Walker, an energy consultant with IBM Global Services. "Certainly, it's not something that many customers ask us about today."

However, Walker argued that this is something that's going to change over the next few years, as IT departments are forced to face up to the true cost of running their data centres. "Energy efficiency won't be driven by environmental issues; realistically, it's going to be because the finance director wants to cut the electricity bills," he said.

According to one recent US survey, data centres account for 1.5 percent of all the power consumed in that county. The cost of powering data centres is estimated to be $4.6bn (£2.2bn) each year, and power requirements are predicted to double within the next four years. Assuming power prices remain steady, that means we could be spending almost $10bn a year powering data centres by 2011.

The cost of electricity is only one factor that will put energy efficiency on the agenda, observed Graham Titterington, a principal analyst with Ovum. "Companies are simply going to hit a point when this is a crisis; when the next server will cost millions because they need to build a new data centre, to get more power or to get more space," he said.

The good news is that experts reckon that being more energy efficient could drive down power consumption in the data centre to 2001 levels — saving around 15 percent on current energy costs.

The bad news is that measuring your company's green credentials is far from straightforward. "The obvious answer is just to look at the electricity bills. They'll tell you how much power you're using, and how much it costs," said Walker. "However, that's a very blunt instrument and won't tell you an awful lot."

Instead, you could use standard calculations to translate your energy consumption into a carbon-output figure, using, for example, the calculators developed by the Energy Saving Trust and The CarbonNeutral Company. The problem is that coming up with a carbon-output figure isn't particularly useful, according to Ted Shann, a sustainability manager with BT. "Knowing how much energy you use or how much carbon you produce isn't very useful in practical terms," he said. "Apart from changing your energy supplier, what do you do?"

The first step when it comes to measuring your environmental credentials is knowing exactly what to measure. This means analysing the data centre to understand exactly what energy is consumed, and where. Unless you know what elements of the data centre are using power, it's impossible to improve energy efficiency, Walker said. "Remember: you can only control what you can measure, so you need a good understanding of how much power each service uses to start with."

The first item on the list is the IT infrastructure itself, which is likely to account for around 45 percent of the energy bill, said Walker. To help customers get a clear idea of the power consumption of servers, IBM has introduced what it calls "active power management" in several of its ranges. For example, the blade servers have an in-built Active Energy Manager which gives real-time information about energy usage. The System z features IBM's "gas gauge", which performs a similar function.

This type of feature, which is also available on HP servers, is important because IT managers are otherwise relying on the maximum power-consumption figures for...

...the servers themselves, said Titterington. "There's a figure on the box that says how many watts this thing uses, and you provision cooling and power on that basis," he said. "However, if you're only using two-thirds of the capacity, that's going to have an impact on the power and cooling you'll need."

One challenge when measuring the energy efficiency of servers is allowing for so-called "embedded carbon", added Andy Cox, a managing consultant with Morse. "There is energy associated with the design, manufacture and disposal of servers, so it's not simply a case of switching out all your kit for newer, greener models," he said. "In some cases, your overall energy costs might be lower if you keep an older machine for a while longer."

However, Shann pointed out that: "The biggest benefits often don't come from technology, but from people. So, if you consolidate servers, you may reduce management costs and thereby reduce the number of people commuting to the data centre. That's going to have an impact on energy and carbon."

The IT infrastructure is, of course, only a fraction of the overall energy picture in the data centre. The next biggest energy consumer is air conditioning and chilling — something that is virtually impossible to measure accurately unless you are building a new data centre with separate power supplies for cooling, says Titterington.

Some vendors are beginning to offer smarter cooling systems that should provide greater insight into their energy consumption. For example, HP recently launched its Thermal Zone Mapping offering, which measures existing conditions and predicts the effects of moving or adjusting cooling systems. The company has also developed a product called Dynamic Smart Cooling, software that can control the performance and output of cooling units more precisely.

After the IT infrastructure and cooling, the other major energy costs in a data centre will be due to UPSs (uninterruptible power supplies) and AC/DC conversion. Again, these may be difficult to accurately measure, but it should be possible to measure the energy requirements of such devices against their utilisation.

If this all sounds like too much hard work (and most analysts agree that an accurate energy audit is beyond the scope of most data-centre managers), an increasing number of vendors will crunch the numbers on your behalf.

BT offers customers a carbon-impact assessment, which is a vendor-neutral assessment of the IT infrastructure. IBM, meanwhile, offers an environmental-impact study that will analyse the end-to-end energy requirements of a data centre. An inspection by IBM Global Technology Services costs from $50,000 for a 30,000-square-foot data centre, the company says.

Most companies will be able to get a reasonably accurate impression of their energy ratings using a couple of days of consultancy, said Cox. "When we work with a client, we're looking at the life cycle of a piece of technology, and the complete cost of that," he explained. "We can then compare that with the benefit the company derives from a product in that specific context."

Cox agreed that the lack of standard calculations for this kind of assessment can lead to confusion, but he said he believes this is inevitable. "Personally, I don't think it's realistic to have industry-standard calculators for this kind of thing," he said. "There are so many different servers and platforms, each with different spin rates, different utilisations — it's impossible to measure that in a standard way."

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