When the first comprehensive report in years to examine energy use by computer servers was published in February 2007, it was greeted with surprise by industry insiders. Jonathan Koomey, a staff scientist at Lawrence Berkeley National Laboratory in California, found that worldwide power consumption by servers had doubled between 2000 and 2005. 鈥淓veryone thought CO2 emissions were a problem for transportation and big energy,鈥� says Bill St Arnaud of Canarie, Canada鈥檚 internet development organisation in Ottawa, Ontario.
Since then a raft of have highlighted the rocketing energy demands made by computers (See Chart). One of them, a report from UK-based Global Action Plan, puts carbon dioxide emissions from information and communications technology on the same level as that of the aviation industry 鈥� 2 per cent of global emissions.
As it turns out, many of the tech titans were already on the case. A week after Koomey鈥檚 report came out, industry giants including Microsoft, Intel, Dell, IBM and Sun Microsystems forged a collaboration known as . Their aim was to attack a host of hardware and software inefficiencies in data centres 鈥� farms of servers that store and retrieve online information. They regard the problem as so large that collaboration is essential. 鈥淭here was a recognition that there was a problem in energy efficiency in data centres that was too vast to be solved by any one company,鈥� says Green Grid director Lawrence Lamers of software company VMware in Palo Alto, California, which makes the so-called virtualisation software regarded by many companies as a prime way to save energy.
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At about the same time, energy consultancies identified the problems associated with 鈥渟erver sprawl鈥� and began to float ideas for possible solutions. These included solar and hydroelectric power, and converting alternating current from the mains to direct current (DC) just once in the data centre, instead of repeating the process many times at different servers, as happens today (New 杏吧原创, 15 December 2006, p 24).
Although some data centres, including Google鈥檚, use some renewable energy, these measures are unlikely to be enough. DC conversion requires significant changes to infrastructure, and companies are looking for technologies they can implement immediately.
Green Grid director, Mark Monroe of Sun Microsystems, points out that another major factor driving companies to reduce energy consumption is concern about supply. 鈥淲e are trying to make data centres efficient enough so that they don鈥檛 outstrip energy availability,鈥� he says.
The need for greener computing is huge. Whenever you download music, send an email, access medical records, or make a credit card transaction, the actions are processed in a data centre. 鈥淭hree years ago, YouTube didn鈥檛 exist,鈥� Lamers says. 鈥淣ow there are hundreds of millions of videos being downloaded by millions of users. Yahoo is giving away free email with unlimited storage. Do you know how many servers are required for millions of users to store gazillions of emails?鈥�
鈥淒o you know how many servers you need to store gazillions of emails?鈥�
The Green Grid鈥檚 biggest achievement to date is a first attempt at finding a standardised way to measure the efficiency of data centres. This would allow customers to compare centres and companies to identify the worst offenders and upgrade them.
Some individual member companies are already moving beyond this. Take IBM, which provides data storage and number crunching services for the financial, pharmaceutical and retail sectors. In May it pledged to invest $1 billion annually in a project called , which aims to double computing capacity at IBM鈥檚 data centres without increasing energy consumption. 鈥淭his is absolutely one of IBM鈥檚 key plays right now,鈥� says Chris Scott, head of IBM data centre services for north-east Europe. 鈥淚t鈥檚 saving us money, it鈥檚 giving us growth capacity, and it鈥檚 the right thing to do for the environment.鈥�
Like many members of the Green Grid, IBM is making virtualisation software a central part of its greening strategy. First used in the 1960s as a way to divide large mainframe computers into smaller parts, each capable of performing its own small task simultaneously, virtualisation is now seen as the low-hanging fruit in data centres鈥� green transition.
Virtualisation software creates multiple 鈥渧irtual machines鈥� (VMs), which are layers of software that emulate a particular type of hardware. Each VM sits between the actual hardware and a specific software application, and looks like hardware to the application. Running applications on VMs instead of directly on the hardware means the separate applications can鈥檛 interfere with each other, and if one application crashes, it doesn鈥檛 affect the others.
When servers replaced mainframes, there was no need to partition them with virtualisation as each server was built to execute one application. But the processing power of servers has now increased to the point that running only one program per server typically means using less than 15 per cent of its capacity. The obvious answer is to run several applications on a single server, as with mainframes.
In 2001, VMware introduced the first virtualisation software written specifically for the type of servers widely used in data centres. 鈥淚t makes the difference between buying 10 servers or buying one,鈥� says Bogomil Balkansky at VMware. 鈥淐ustomers are able to save 70 to 80 per cent on energy use. It鈥檚 the best way to immediately and dramatically reduce power consumption in the data centre.鈥� In August, as a result, IBM was able to replace 3900 of its Intel servers with 33 larger ones with more efficient multicore chips (New 杏吧原创, 10 March, p 26). 鈥淭hat is an 80 per cent reduction in energy consumption and an 85 per cent reduction in space,鈥� Scott says.
Virtualisation and multicore chips aren鈥檛 the only ways to green data centres. Other Green Grid members believe that an important contribution is improving the efficiency of applications themselves. Arjan van de Ven, a software engineer at chip maker Intel, is leading an initiative called to make the popular Linux open-source operating system more efficient.
Many companies, including Google, run their data centres on Linux. By tweaking existing Linux code, Van de Ven and his team were able to detect which programs were behaving badly. This revealed that Linux was performing a lot of small, senseless tasks.
One example was 鈥渙ndemand鈥�, a program designed to save power by checking the computer鈥檚 central processing unit (CPU) for activity and reducing power consumption when activity was low. The researchers discovered that it was contacting the CPU several hundred times a second, which was enough to make the CPU more active than it would have been without ondemand running at all. 鈥淗ere we have a piece of software designed to save you power that is actually wasting power,鈥� Van de Ven says. Because Linux is open-source they were able to rewrite the program so that it checks CPU activity less often.
The team also found energy-wasters in a version of Linux that runs on personal computers. These included a program that checks the email inbox 100 times per second even though the inbox only asks the server if there is new email every 5 minutes; a clock that updates every second even though it displays the time in minutes; and a program that asks the hardware 10 times a second if the volume of a speaker has changed even though another program is already set up to tell the hardware when speaker volume changes. 鈥淭hese sound like little things, but if you have 40 programs that do this, they add up,鈥� says Van de Ven. The team has made its upgrades available via various open-source software mailing lists over the last year, and two versions of Linux for laptops have incorporated them.
Along with Google and the conservation group WWF, Intel is also a member of the , a collaboration Intel helped to found in June 2007. Rather than focusing on the data centre as a whole, the CSCI is looking at how to improve the efficiency of individual servers. One strategy that Google has already implemented on some computers is eliminating voltage conversions within individual computers.
In the future, CSCI directors imagine having personal computers that can adjust their energy consumption in proportion to their workload. Today鈥檚 computers tend to use the same amount of energy, no matter what they are doing.
Bill Weihl of Google, who is also co-chair of the CSCI, is optimistic that its efforts and that of the Green Grid will reduce the amount of energy data centres and personal computers use. Whether it is enough to offset the predicted growth in computer use over the next 20 years 鈥渋s hard to predict鈥�, he says.
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