It's been a while since we've done a comprehensive article on green computing. So much is happening in this industry that it won't all fit into one article. With this first update, I'll focus on data centers; next week's second update will focus on green personal computers, components, and services.
Before getting started, though, it must be said that greening the computer industry is touching off an unprecedented level of cooperation and information-sharing among companies, government, and laboratories. The Server Specs blog recently interviewed industry consultant Deborah Grove, who said it was unlike anything she'd seen in 24 years in high tech. "There is increased transparency... Executives are offering up what worked and what didn't work instead of everybody having to reinvent the wheel," said Deborah. "It's tangible in the sense of better products... Organizations are taking on the responsibilities that they can deliver on -- not worrying about turf, just trying to get the job done."
Deborah's largely referring to the Green Grid, a consortium of industry leaders (like AMD, Intel, Dell, HP, IBM, Sun, and others who are normally competitors) to share data and strategies for greener data centers. Green Grid's membership also includes the Pacific Gas and Electric Company (better known as PG&E), and it recently announced a collaboration agreement with the U.S. Department of Energy.
Data Centers
Data centers (also called server farms) are where companies like Google or Amazon or internet service providers locate the hundreds or thousands of computer servers that provide their online services. As Worldchanging's Joel Makower has written before in a couple great articles, data centers use massive amounts of electricity; large ones can use megawatts of power, with each square meter using as much power as an entire average US home. An EPA report says data centers consume 1.5% of the total electricity used in the US.
It's not just the computers themselves that use all this power: the combined heat output of all these servers, hard drives and network gear is so large that massive air conditioning is required to keep it all from overheating. "Cooling is about 60 percent of the power costs in a data center because of inefficiency," said Hewlett Packard executive Paul Perez in Data Center News. "The way data centers are cooled today is like cutting butter with a chain saw." Cooling capacity is often the limiting factor of how big these systems can be -- I've talked with more than one engineer whose data center facility sat half empty or more; even though there was plenty of room for more servers, the building's air conditioning was maxed out.
How can data centers get greener?
Lawrence Berkeley Labs has published a white paper titled Best Practices for Data Centers. Researchers measured 21 facilities and recommended strategies that they found most successful. These include several HVAC (air conditioning) improvement strategies, water cooling, efficient power supply and conversion, and on-site power generation. Other useful design strategies the paper does not mention are virtualization and "blade" servers. A paper at GreenIT titled Greening the Data Center: A 5-Step Method actually lists many more than five strategies, similar to those suggested by the LBL, but a bit newer and written for the layman. One step specifically emphasized is getting to know your facilities managers, as they are the ones who know about your HVAC system and energy bills. CIO.com also has a list of six strategies, including not letting your cabling block the flow of your air conditioning system, and moving power and cooling systems outside the data center -- even outside the building.
Water cooling is both more efficient than air cooling and can handle higher heat loads, simply because water is far more conductive of heat and has much higher thermal mass than air. It's been slow to catch on because administrators are paranoid about leaks (water and electronics certainly don't mix well), but systems are available now that have been proven reliable. IBM and HP have water-cooled server racks, and Knurr's even won a design award. The Pacific Northwest National Lab even proposed cooling via liquid metal, so that the fluid can be pumped hydromagnetically, with no moving parts.
Good power conversion minimizes the losses that occur when converting AC power to DC and back; this might not sound important, but it's one of the biggest inefficiencies in the system currently. In a server farm, most power coming from the wall outlet gets converted from AC to DC in an uninterruptible power supply (UPS) to safeguard against power outages or spikes; but then it is converted back into three-phase AC power and sent to the server racks, at which point it is once again converted from AC to DC, usually at the power supply for each server. Losses at each stage can be from 5 percent to 20 percent or more, and traditional power supplies stay on whether or not the components they power are actually being used.
Centralizing the power conversion can radically improve system efficiency, partly by eliminating the re-conversion from DC to AC back to DC, but also because a large efficient power supply can be economically competitive with an inefficient one, but small efficient power supplies (such as individual computers have) are still significantly more expensive than inefficient ones. Every gain in power conversion efficiency is twofold, since reducing power loss also means reducing heat loads on the air conditioning system.
Virtualization is a way of making one computer behave like several computers. Anyone who uses Parallels software to run Windows on a Mac has used virtualization, and knows its performance advantage: the virtual machine is isolated from the rest of the computer, so even the worst blue-screen-of-death software meltdown won't harm anything outside the virtual machine. Internet service providers also like them for providing bite-sized administrative domains to users without having to have buildings full of bite-sized hardware. They're also useful for green computing, because they consolidate what would ordinarily be several CPUs, motherboards, disks, etc. all into one machine. This reduces material use not only by letting several virtual machines share one physical machine, but a large virtual machine can be comprised of many smaller older physical machines, allowing hardware to remain in use longer. Virtualization also reduces energy use, because many components use the same amount of power whether they're being used or sitting idle.
Blade Servers are a relatively new architecture for server racks, where each individual server is less self-contained and more dependent on the rack for power conversion, cooling, networking, and other elements that have traditionally been redundantly located in every server in a rack. This makes for both a more compact system and a more efficient system, because it allows for things like the centralized power conversion and water cooling mentioned above.
The new architecture is taking off, and even has its own industry association promoting it now: Blade.org, which has touted its' systems efficiencies.
Dave Ohara, writing for Microsoft TechNet, takes more of a business / structural approach, rather than specific system design strategies (aside from power metering). Here's his list of ten qualities of efficient data centers:
1. Meters are used to break down energy usage to the level of components (such as a 2U server, a 4U server, a switch, a SAN, and a UPS) and which business units are charged for the power being used by those components.
2. Energy usage is continuously monitored to determine peak and low energy demands.
3. Energy capacities are monitored on a total datacenter level all the way down to circuits to make sure all circuits are within acceptable limits.
4. The energy savings plan is documented and rewarded.
5. The energy savings plan is reviewed regularly and corrective action is taken to address failures.
6. Determining how costs are charged back to business units is used to shape behavior, encouraging energy savings among independent business units. This point must be driven at the executive level.
7. CPU throttling is enabled on the servers, and the performance lab measures the range of power consumed under a variety of loads.
8. Thermal profiling is used to identify hot spots and overcooling.
9. IT performance engineering includes energy efficiency measurements.
10. Feedback of live data is available to individual organizations, allowing them to react appropriately.
He also points out that newer server software often has power-throttling capability, which alone can provide significant benefits: "Windows Server [2008] with default energy savings enabled could reduce consumption by up to 20 percent" in some systems, he claims. We've also previously mentioned the company Verdiem, which makes power management software for IT systems. Verdiem claims its software has saved customers a total of over $43 million, and eliminated almost 369 thousand tons of CO2 emissions.
According to Data Center News, "HP plans to practice what it preaches in its own operations by consolidating 85 of its data centers worldwide into just six larger data centers, using virtualization, blade servers, combining applications and smart planning". Fast Company also mentioned IBM's Project Big Green, "a billion-dollar-a-year investment in technology to double the efficiency of servers that currently can run at only 30 percent capacity--a move that could save clients 40% in IT-power costs."
How green is your data center?
These are still early days, so it's hard to know how green your data center is compared with others. Lawrence Berkeley Labs has the best data so far (the paper above cites data for energy use by 21 centers, and more work has been done since then), but the Green Grid is developing a set of measurements that can be used to determine how efficient your data center is. Currently they only define Power Usage Effectiveness and its reciprocal, Data Center Infrastructure Efficiency, but they plan to break this down into more granular measurements like Cooling Load Factor and Power Load Factor, or even efficiency standards for all the different types of gear in a data center (switch gear, chillers, uninterruptible power supplies, etc.) just like the EPA has done for appliances with their EnergyGuide labels.
The bigger picture
Clearly, greener data centers are a crucial part of the green computing world. However, they are still vastly outnumbered by personal computers. The Tech Target paper quoted above notes that
For every data center machine, there can be from 50 to more than 250 end-user computers. The average active, powered-on desktop computer consumes 100 to 300 watts of electricity. Much of the electricity that comes through the power cord of the computer is turned into heat and power conversion waste through the PC power supply."
Next week I'll talk about power supplies and other elements of green computing on the level of personal machines.
