Techniques to implement in green data centres to ...

372

Int. J. Global Warming, Vol. 3, No. 4, 2011

Techniques to implement in green data centres to achieve energy efficiency and reduce global warming effects Mueen Uddin* and Azizah Abdul Rahman Department of Information Systems, Universiti Teknologi Malaysia, UTM, Skudai, 81310, Malaysia Fax: (006) 07 5537811 E-mail: [email protected] E-mail: [email protected] *Corresponding author Abstract: Energy demand in data centre industry is growing rapidly as computing technology changes and Information Technology (IT) professionals seek to maximise performance of data centres. A multitude of methods have been used to estimate and quantify energy intensity. Rising energy costs, continuing concerns about global economic downturn and global warming effects has leaded ways for energy efficient data centres. The goal of computer system design has been shifted to power and energy efficiency. This paper highlights strategies and techniques that provide energy savings in data centre like reducing frequent hardware purchases, power/cooling cost reductions, green metrics, shrinking data storage, workload consolidation and reducing physical servers. Keywords: data centre; green IT; energy efficiency; global warming; virtualisation; metrics. Reference to this paper should be made as follows: Uddin, M. and Rahman, A.A. (2011) ‘Techniques to implement in green data centres to achieve energy efficiency and reduce global warming effects’, Int. J. Global Warming, Vol. 3, No. 4, pp.372–389. Biographical notes: Mueen Uddin is a PhD Fellow at Universiti Teknologi Malaysia UTM. His research interests include green IT, energy efficient data centres, green metrics, global warming effects, virtualisation, cloud computing, digital content protection and deep packet inspection, intrusion detection and prevention systems, MANET routing protocols. He has BS and MS in Computer Sciences from Isra University Pakistan with speciality in Information networks. He has 15 international journal publications. Azizah Abdul Rahman is an Associate Professor at the University Technology Malaysia. Her research interests include designing and implementing techniques for information systems in an organisational perspective, knowledge management, management information systems, and implementing security protocols for E-businesses. She has BS and MS from USA, and PhD in information systems from Universiti Teknologi Malaysia. She is a member of the IEEE, AIS, ACM, and JIS. She is a renowned researcher with over 40 publications in various international journals and conferences.

Copyright © 2011 Inderscience Enterprises Ltd.

Techniques to implement in green data centres

1

373

Introduction

In recent years, commercial, organisational and political landscapes have changed fundamentally for data centre operators due to the confluence of apparently incompatible demands and constraints. The energy use and environmental impact of data centres has recently become a significant issue for both operators and policy makers. The public perception of climate change and environmental impact has changed substantially, delivering real commercial impact for corporate environmental policy and social responsibility. Unfortunately, data centres represent a relatively easy target due to very high density of energy consumption and ease of measurement in comparison to other, possibly more significant areas of IT energy use. Policy makers have identified IT, specifically data centre energy use as one of the fastest rising sectors (Newcombe, 2009). Powerful business applications, internet fuelled data growth, compliance pressures, governance, litigation, defence and other multiple pressures are spurring corporations to produce and store more data than ever before. Server, storage and networking vendors have responded by producing ever more powerful equipment to boost performance, speed, scalability and availability. As the data centre industry has evolved to include higher levels of intelligence, its corresponding power requirements have grown and will continue to do so (Gartner, 2008). This correlation between function, intelligence, feature sets and corresponding power requirements is a crucial concept. Ultimately, the end user must decide how to balance power consumption with service levels for voice, video, and data. Corporations are buying more and more energy to keep the lights on and the disks spinning, and to run the heavy duty cooling required to offset heat generated by dense storage and servers. This is a large-scale problem, and the goal of the green data centre movement is to control energy output on this large scale. This green approach will yield the large savings needed to offset spiralling energy costs and at the same time reduce the quantity of Greenhouse Gases (GHG) emitted by the overwhelming consumption of energy, and hence, will reduce the overall effects of global warming and achieve environment-friendly data centres. In situations where energy cost is a lower priority than data centre size, green technologies can allow companies to control the growth of their data centres by minimising their environmental impact. It has taken more than 30 years for the data centre industry to evolve to a point of modularity that is conducive to alignment of efficiencies in use and design across disparate infrastructures. The modern environmental or ‘green’ movement has also taken 30 years to evolve to a point where the economics of sustainable practices are well understood (Molla et al., 2009). Traditionally, environmentalism has been perceived to be at odds with economic prosperity. Environmental stewardship encompasses the notion of balancing current resource consumption with the resource requirements of future generations. For example, the landmark 1987 Brundtland report (published under the title Our Common Future: World Commission on Environment and Development) defined sustainable development as meeting “the needs of the present without compromising the ability of future generations to meet their own needs” (Benjamin and Marilyn, 2010). Enterprises are being pressed to deal with continuously increasing demands for processing applications and to work with hard limits to power, cooling and space growth in their data centres. The demands for increased computing capabilities are colliding with real world pressures associated with the costs of both acquiring more servers to meet the demands and operating those servers over time (Koomey, 2007). Power and cooling costs have placed limits on build outs for new data centres, and maintenance costs must be kept

374

M. Uddin and A.A. Rahman

in check. As big as this challenge is, there are ways to meet it now and in the near future. In fact, the primary equation sounds deceptively simple: reduce data capacity and reduce energy consumption. The trick, of course, is to shrink (read: compress, tier and optimise) data in complex data centre environments where large scale deletions may not be possible. This is where crucial software and hardware technologies like virtualisation, consolidation, live migration and cloud computing dramatically reduce the stored data and condense physical equipments like servers to achieve efficiency at a broader level (Mueen and Azizah, 2010). The energy efficient and green data centre is gathering momentum as organisations have started realising its importance in energy conservation and sustainable development. It is applied to new technologies that can help in cutting down data centre energy costs and in saving energy, which is synonymous to saving money. It has a big role to play in reducing power consumption in the data centre (IBM, 2008). It explores key capabilities to look for when investing in data centre power management and discuss the associated business values that can be derived from energy management solutions. A data centre is a special facility that physically houses various equipment, such as computers, servers (e.g., web servers, application servers, database servers), switches routers, data storage devices, load balancers, wire cages or closets, vaults, racks, and related equipments. It can store, manage, process, and exchange digital data and information and provide application or management services for various data processing applications. Because there is no global industry wide recognised standard available today that defines a green data centre, each organisation needs to define what green means to it. For the sake of this document, a data centre is generally considered a purpose built facility or portion thereof that houses a business’s mission-critical applications. A green connotation supposes that the facility has either been retrofitted or initially designed to mitigate its power consumption through the strategic application of available technologies. The long term goal of green data centre operation is to achieve carbon neutrality. Whatever a data centre manager’s definition of green, a moral, financial, or capacity motivation to pursuing this agenda can be assumed. For a business operation to demonstrate success in implementing a green strategy, the strategy must be measurable. A variety of measurement methodology options are available today. Many of these options may be too costly in terms of time and resources to implement when the scope of internal integration is accounted for. To IT, knowledge is power, but the collection and interpretation of the vast quantities of data in a data centre must be simple, intuitive and reliable. The response from many IT professionals, data centre managers and IT managers is positive. They realised that energy efficient data centres should be implemented in a short period of time and with very little expense and minimal staff involvement to achieve a positive impact and help protect the environment and at the same time reduce worldwide global warming effects. This paper proposes some techniques and emphasises the need to implement them in data centres to achieve efficiency and reduce GHG to make data centres environment friendly. With the concept of green in mind, energy efficiency and environmental considerations should be in the main spotlight for all data centre managers. The combination of IT infrastructure and eco-sustainability perspectives defines green IT as an organisation’s ability to systematically apply environmental sustainability criteria (such as pollution prevention, product stewardship, use of clean technologies) to the design, production, sourcing, use and disposal of the IT technical

Techniques to implement in green data centres

375

infrastructure as well as within the human and managerial components of the IT infrastructure (Molla et al., 2009).

2

Background and related work

The immense use of IT has exploded in all areas of business activities, offering great benefits and convenience and irreversibly transforming businesses and societies into a global world. But at the same time, IT has been contributing tremendously towards environmental problems. Unfortunately, most people including many IT professionals don’t realise this. IT affects our environment in several different ways. Each stage of a computer’s life from production and use to disposal presents environmental challenges. Manufacturing computers and their various electronic and non-electronic components consumes electricity, raw materials, chemicals, and water, and it generates hazardous waste. All these factors contribute towards environment problems. Globally, total electrical energy consumption by data centres, servers, and computers is steadily increasing. The increase in energy consumption results in increased GHG emissions, as most of the electricity is generated by burning coal, oil, or gas. Countless old computers and other electronic hardware, which contain toxic materials are discarded within a couple of years after purchase, end up in landfills, polluting the earth and contaminating water. The increased number of computers in use and their frequent replacements make the environmental impact of IT a major concern. Consequently, there’s increasing pressure on us to make IT environmentally friendly (John, 2000). Data centre facilities are become common and essential to the functioning of businesses, communications, academic, and governmental systems, since every office is shifting from paper-based to digital information management. Data centres are found in nearly every sector of the economy, including financial services, media, high-tech, universities, government institutions, and many others uses that operate data centres to aid business processes, information management, and communications functions (Daim et al., 2009). Energy efficiency in computing has historically improved much more slowly than performance or cost (Belady, 2007); there is a continuous day-to-day increase in the demand for data processing and storage by end users in all businesses, especially e-businesses. This demand is driven by several factors like the increased use of electronic transactions in financial services, such as online banking and electronic trading, the growing use of internet communication and entertainment, the shift to electronic medical records for healthcare, the growth in global commerce and services, and the adoption of satellite navigation and electronic shipment tracking in transportation. Over the past decade, however, power and energy have begun to severely constrain component, system, and data centre designs. In data centres, power and energy consumption are becoming pressing concerns. In the USA, the power consumed by volume servers doubled between 2000 and 2006, and the Environmental Protection Agency (EPA) predicts that it will double again between 2006 and 2011 (EPA, 2007). There has been mounting interest in opportunities for an energy efficient government sector. The energy used by the servers and data centres is significant. It is estimated that this sector consumed about 61 billion kilowatt-hours (kWh) in 2006 for a total electricity cost of about $4.5 billion. The energy use of the nation‘s servers and data centres in 2010 is estimated to be more than double the electricity that was consumed for this purpose in 2000. The USEPA came out with a report that assesses current trends in energy use and

376

M. Uddin and A.A. Rahman

energy costs of data centres and servers in the USA and outlines existing and emerging opportunities for improved energy efficiency (EPA, 2009). It provides particular information on the costs of data centres and servers to the federal government and opportunities for reducing those costs through improved efficiency. It also makes recommendations for pursuing these energy efficiency opportunities broadly across the country through the use of information and incentive-based programmes (EPA, 2007, 2008). Electricity usage costs have become an increasing fraction of the total cost of ownership for data centres. It is possible to dramatically reduce the electricity consumption of typical data centres through appropriate design of the network critical physical infrastructure and through the design of the IT architecture (Rasmussen, 2006). Data centre inefficiency is a widespread and growing concern, soaring costs and ever increasing environmental footprints are impacting the corporate investment landscape, threatening profitability and inviting board and regulatory scrutiny. There is a strong need to outline ways for organisations to address the twin challenges of rising data centre energy usage and GHG emissions (James et al., 2008). Organisations are now more concerned about environment and energy saving models and are focusing on how IT professionals can do better power and cooling design to achieve maximum efficiency in their data centres through the strategic application of technologies and best practices (Cisco, 2007). Servers and storage components are not the only systems that use energy in data centres, but cooling equipment often uses as much power as the systems themselves. Adding to that, the energy used to light the data centre, power distribution losses, and other factors give a closer look at how power is actually consumed within data centres. More effective use of the existing power supply corresponds to fewer emissions resulting from commercial power generation. From this perspective, blade designs are proposed and are performing quite well. Blade form factors per work unit performed consume power and cooling more efficiently than do standalone 1-, 2-, and 4-Rack Unit (RU) servers. Because data centre efficiency is in part a cumulative calculation of how disparate IT infrastructure interoperates with supporting facilities, blade capacity and density requirements must be aligned with facility design to achieve maximum efficiency benefits. Each type of power usage gives an opportunity to reduce total power consumption and CO2 emissions (Green Grid, 2009). The computation of total emissions resulting from electric energy consumption is relatively straightforward. Total emissions (T) equals the energy consumed (E) multiplied by the GHG emission Intensity (I) of that energy use, or (T = E × I). The measurement of energy consumption (E) can be sourced directly from the electricity meter of the data centre itself, while the emissions Intensity (I) can be calculated by the energy supplier (the power company) as an average value based on the sources of fuel providing energy to that data centre. A particular policy might reduce the total emissions by improving energy efficiency, thereby reducing the rate of energy consumption while remaining at fixed emissions intensity. Alternately, a policy approach might focus exclusively on the use of lower-emission clean fuels such as wind, solar, biomass, or hydroelectric, which would reduce total emissions by reducing emissions intensity while maintaining the rate of energy consumption. Some policies may reduce total emissions by targeting both energy consumption and emissions intensity.

Techniques to implement in green data centres

377

The recent study by (The Climate Group and the Global e Sustainability Initiative, 2008) has analysed these impacts in terms of their CO2 emissions. It forecasts that the global data centre footprint, including equipment used and embodied carbon, will rise to more than 259 million tonnes in 2020, more than triple the 76 million tonnes of CO2 equivalent emissions in 2002. These total data centre emission figures represent about 14% and 18% respectively of the total Information Communication Technology (ICT) related emissions. ICT related CO2 equivalent emissions are said to be about 2% of the total global emissions, and data centres account for around 0.3% of global CO2 equivalent emissions (Info-tech Research Group, 2008). Emissions of GHG from aviation, shipping, transportation, telecommunications and the manufacturing of cement are rising fast, but the emissions from IT are rising faster. Reductions achieved through the use of green IT in other key economic sectors would be five times greater than the growth in emissions from the IT sector. That’s quite something, given that the growth in emissions from IT is projected to increase from 3% of total global emissions in 2009 to a whopping 6% by 2020, as depicted in Table 1 (Info-tech Research Group, 2008). Table 1

CO2 emissions (carbon foot print) the climate group and the global e-sustainability initiative Smart 2020 Emissions 2007 MtCO2e

Percentage 2007

Emissions 2020 MtCO2e

Percentage 2020

World

830

100%

1430

100%

Server farms/ data centres

116

14%

257

18%

Telecom infrastructure and devices

307

37%

358

25%

PCs and peripherals

407

49%

815

57%

World

As recently as September 2000, it was estimated that worldwide spending for ICT products and services will reach $2.6 trillion in 2005 (Koomey, 2007). Even with the recent economic slowdown, continued growth in this sector is expected. One of the key challenges of the rising number of data centres is the increasing demand for energy consumption by servers and other components in data centres and the continuous increase in the emission of GHG (CO2) – very hazardous for global warming. Organisations are now become more concerned about their environment and energy saving models (Cisco, 2007). With recent concerns about electricity supply in parts of the USA, both utilities and data centre owners face challenges in meeting data centre electricity requirements with the required levels of reliability (Kathan and Thomas, 2001). To overcome some of the environmental issues, green IT spans many focus areas and activities, including power management; data centre design, layout, and location; the use of biodegradable materials; regulatory compliance; green metrics and green labelling; carbon footprint assessment tools and methodologies; and environment-related risk mitigation. A growing number of IT vendors and users have begun to turn their attention toward green IT, triggered by the imminent introduction of more green taxes and regulations; there will be a major increase in demand for green IT products and solutions. Green IT will be the hot topic for years to come, because it now becomes imperative to

378

M. Uddin and A.A. Rahman

develop environmentally sustainable IT, from both an economic and an environmental viewpoint (Murugesan, 2010).

3

Problem definition

In the past, energy was never IT’s concern, it was cheap and plentiful, and was the sole concern of the facilities managers and accountants who paid the utility bills. Even as data centre equipment grew in size and quantity to handle the glut of data being produced, facilities departments simply increased the budget and accounting departments paid the bills. But data centre energy costs continued their inexorable rise, and today are topping $4.5 billion a year in the USA alone. Financial planners howled and CEOs unhappily watched energy costs take a drastic bite out of profits. From servers to storage to networks, IT was deploying faster and denser equipment to handle larger and larger data volumes and meet more demanding Service Level Agreements (SLAs). Each new element was shoehorned into data centre racks until the physical plant groaned under the load, with creaking raised floors, inefficient cooling and raging electricity bills. Making matters even worse, some urban centres and states reported dwindling power supplies. Many data centre managers realised that they had the space to add equipment, but would not have enough electricity available to power it. Thus, IT’s defining moment was not so much the high energy bills, but the fact that soon data centres would simply be too energy starved to accept the server, networking and storage resources that were being demanded. With the growing need for petabyte level scaling, there was simply no way to feed the beast. Global warming pressures also caused the need for environment friendly and carbon-neutral data centres. Many businesses are still forced to build new data centres in areas with more abundant energy, bearing the horrific expense of building and moving into new facilities, not to mention relocating and replacing the workforce. The question of energy in the data centre is a large and complex one, and its answer must be holistic and comprehensive.

4

Proposed work

One of the areas of IT businesses where environmental sustainability is becoming imperative is data centres. Energy efficient technologies, smart design and proper preventative maintenance procedures can significantly decrease data centre energy demands. During the time of rapid data centre expansion, operation of such centres was very lucrative, with revenues estimated as high as $1 million per minute (Holusha, 2001). According to many people in the internet-hosting industry, getting a new data centre on line as fast as possible (i.e., minimising time to market) was the overriding factor in designing and building data centres. However, haste to install data centres, lack of accepted and standardised design guidelines and lack of financial incentives to save energy has led to inefficient design, poor design implementation, and use of energy inefficient technologies in data centres (Mitchell-Jackson, 2001). Data centre operators place a high premium on power reliability and quality, and tend to be very concerned that changes in technology or practices from what they are already using will reduce reliability. Thus, energy efficient technologies and improved

Techniques to implement in green data centres

379

management practices that increase reliability or power quality while saving energy are more likely to be considered than ones that do not offer increased reliability. Further, solutions that are modular and scalable will benefit data centres because they can be expanded as the data centre builds out, reducing upfront capital cost, and will offer consistency between data centres of different sizes, reducing the need to maintain many dissimilar systems across facilities. There is significant potential for energy efficiency improvements in data centres. Many technologies are either commercially available or will soon be available that could improve the energy efficiency of microprocessors, servers, storage devices, network equipment and infrastructure systems. Still, there are plenty of unexplored, reasonable opportunities to improve energy efficiency. Selection of efficient IT equipment and reducing mechanical infrastructure increases the energy efficiency. Improvements are possible and necessary at the level of the whole facility, i.e., the system level and at the level of individual components. It is not possible to optimise data centre components without considering the system as a whole, still it is true that efficient components are important for achieving an efficient facility; for instance, efficient servers generate less waste heat which reduces the burden on the cooling system. For achieving greatest efficiency, here we will provide a comprehensive approach that explores the opportunities for improvement in many areas of IT and mechanical infrastructure systems.

4.1 Techniques for implementing green data centres The following section will describe different techniques used for implementing green data centres.

4.1.1 Deploy software technologies Software techniques should be adopted and implemented in data centres to control the data growth and shrink demands for storage capacity. As storage scales to petabyte heights, we believe that no other change in the data centre will have as much impact as using innovative software technologies to intelligently manage data growth and effectively control capacity demands. At the heart of the data centre’s energy struggle is the sheer volume of the data it must store. Poorly controlled data growth demands more storage capacity, which in turn draws more electricity and requires more cooling. Since large-scale data deletions are not advisable in a compliance-driven and litigious world, different software solutions like VMware, Microsoft Hypervisor 5 server, etc., will help data centre managers to accommodate workloads such a way as to manage them concurrently and with little overhead. Categorising data centre workloads is an important aspect while greening data centre operations. It requires categorisation of data centre applications and services into measurable units so that energy efficiency metrics can be applied appropriately to measure efficiency.

4.1.2 Express power usage across data centres as SLAs The primary objective of the data centre industry is to provide computing services that meet the business requirements of its end users. Data centre managers need to understand

380

M. Uddin and A.A. Rahman

those requirements and translate them into the centres’ own businesses objectives. It is important for these data centre managers to measure the services delivered and the overall performance of the data centres in terms of capability and availability. To achieve this, SLAs should be set and reached. These SLAs are formal written contracts developed jointly by data centre managers and end users. A good SLA addresses five key aspects of data centres: •

what the provider is promising

•

how the provider will deliver on those promises

•

who will measure delivery, and how

•

what happens if the provider fails to deliver as promised

•

how SLAs will change over time.

These SLAs are critical throughout the data centres’ operations, especially in controlling power usage and standardising metrics. Hardware-based metrics have already made strides with data centre based measurements like those from the Green Grid. The industry association has developed methods to calculate the ratio of total facilities power over total computer component power, and also its inverse. What is lacking is the more complex metrics that must take data value into account. Storage is particularly challenging in this regard, as meaningful storage metrics must not only calculate total power related to the storage device in terms of both energy and cooling usage, but must also calculate the given device performance requirements, capacity, and space requirements. For example, a key driver for a primary array in a transactional environment is performance. The production array can yield energy savings through technologies like adaptive cooling and efficient AC/DC power conversion. In addition to these savings, a large capacity SATA-based archive might use technologies such as Massive Array of Idle Disk (MAID) to save on the high cost of constantly spinning disks. A good SLA is important because it sets boundaries and expectations for the following aspects of data centre service provisioning. 1

Customer commitments: Clearly defined promises reduce the chances of disappointing a customer. These promises also help to stay focused on customer requirements and assure that the internal processes follow the right direction.

2

Key performance indicators for end users: By having these indicators established, it is easy to understand how they can be integrated in a quality improvement process, and this improves end user satisfaction as clear objective.

3

Key performance indicators for internal objectives: SLA drives internal processes by setting a clear, measurable standard of performance. Consequently, internal objectives become clearer and easier to measure.

4

The price of non-conformance: If SLA have penalties (something that many data centre providers prefer to avoid but should not), non-performance can be costly. However, by having penalties defined, the customer understands that the data centre provider truly believes in its ability to achieve the set performance levels. It makes the relationship clear and positive.

Techniques to implement in green data centres

381

4.1.3 Encourage energy efficiency in infrastructure hardware As businesses grow, IT organisations add systems to support data centre loads. If not carefully planned, such additions can result in a sprawling, complex network of systems that consume valuable data centre floor space, create excessive power and cooling demands, and become costly and difficult to manage. The solution is provided by consolidation. Server consolidation brings together applications, databases and services onto fewer, highly reliable servers. By implementing virtualisation techniques, companies can consolidate onto fewer systems that get more work done and cost less to run (Mueen and Azizah, 2010). Virtualisation is emerging as an important tool as organisations look to consolidate redundant and aging infrastructure and create more cost-effective data centres. Indeed, server virtualisation technologies can help organisations quickly recover from disasters, reduce time to market for new services, and better use existing infrastructures to reduce space, power and cooling requirements (Dragovic et al., 2003). Consolidation and virtualisation are the keys to managing infrastructure energy needs in data centres. The ongoing development of energy efficient hardware technologies is also vital to achieving green data centres. Servers and storage represent major energy draws, both for electrical power and cooling, in data centres, and switches require their share as well. Consolidation and virtualisation have already helped to lower consumption, and ongoing engineering for energy efficiency is necessary as well.

4.1.4 Engineer facilities for maximum energy efficiency Storing less data is the key to the green data centre, but new power and cooling technologies are important elements of improving the green quotient in aging data centres and intelligently designing new ones. The most dramatic energy efficiencies will be achieved through the use of software innovations. However, energy-efficient plant technologies like close-coupled cooling and efficient AC/DC power conversion are a significant part of the green data centre. The size of physical elements also figures in this requirement. The less floor space a component requires, the longer an existing data centre can avoid building out. The ultimate impact of integrating the four requirements is an energy-efficient data centre offering up to 80% reduction in energy, cooling, and space-related costs over today s averages. And because these dramatic reductions are led by software technologies that shrink data, Return on Investment (ROI) surrounding data management vastly improves as well. We now turn to a more detailed discussion of this first and most important of the four requirements: deploying software technologies to drastically reduce data and capacity requirements.

4.1.5 Data centre energy efficiency metrics Metrics are instruments to measure and serve as an indicator of progress. The importance of rational, measurable metrics, therefore, becomes imperative to measure and manage data centres. The Green Grid has defined the following characteristics that a data centre metric should possess (Green Grid, 2009). •

the metric name should be clear

•

show initiative

382

M. Uddin and A.A. Rahman

•

the metric should be capable of scaling according to the purpose it was initially designed and created for, and should factor technological, economic, environmental changes, etc.

•

scientifically accurate and precise

•

granular enough to analyse individual aspects

•

should be capable of providing data driven decisions.

While there is a great deal written about data centre energy use, comparisons of energy requirements between them are often difficult or confusing because authors do not always define their energy requirements in a consistent manner. This creates headaches and uncertainty for utilities, which need accurate information to supply the correct amount of electricity to their data centre customers, as well as to gauge whether or not new generation or distribution capital expenses need be incurred to meet these requirements. Utilities and data centre operators often quantify power requirements in terms of power density, or the watts per square foot of floor area (W/ft2) that a building will use. Problems arise when different parties use different definitions of floor area (some may include office spaces, others may not), and different sets of energy using components (some may include energy using equipment outside the computer room, others may not) to define this power density. These issues have been discussed in detail in Jennifer Mitchell-Jackson’s May 2001 thesis, “Energy Needs in an Internet Economy: A Closer Look at Data Centres.” Building on this work, at least four different metrics of power density can be defined and are described in Table 2 (Jennifer and Mitchell-Jackson, 2001). Table 2

Definition of power density

Rack (or product) power density

Power drawn by an individual rack (or product such as a server or tape backup device), divided by its footprint

Simple computer room power density

Power drawn by the computer equipment installed on the raised floor, divided by the raised floor area that houses the equipment

Total computer room power density

Power drawn by the computer equipment and all supporting equipment such as Power Distribution Units (PDUs), Uninterruptible Power Supplies (UPSs), HVAC, and lighting, divided by the raised floor area

Building power density

Total power drawn by the entire building, divided by the total floor area of the building

•

Rack power density: Is generally the highest because a rack packed full of energyintensive computer equipment draws the greatest load per square foot of floor space of all components within a data centre.

•

Simple computer room power density: Is lower than rack power density because the energy required by the racks is spread out over the entire raised floor space, including aisles and non-energised areas, as defined previously in Table 2.

•

Total computer room power density: Is higher than simple computer power density because it includes the power requirements of all equipment that supports the operation of the data centre.

Techniques to implement in green data centres •

383

Building power density: Generally the lowest because it includes floor space that is much less energy-intensive than the computer and support electronics rooms themselves, such as hallways, closets, and standard office spaces.

One of the biggest challenge facing legislators, corporations, and management agencies today is the fact that there is no simple, accurate way to measure and monitor power consumption and its corresponding emissions in real time. This lack is particularly problematic for regulation, and until a comprehensive management system is developed and implemented, green behaviour will be a largely voluntary exercise. Although no global or broadly accepted standards exist today for government bodies to regulate data centre efficiency, there is anecdotal evidence that they are being considered. With the passage of the USA House of Representatives’ Resolution 5646 in July 2006, the EPA’s Energy Star program is now researching data centre energy consumption, industry measures for server efficiency and energy saving technologies. The recently formed Regional Green House Gas Initiative (RGGI), led by nine USA states, is a state government level programme that seeks to provide flexibility in the way that emissions from commercial operations are managed. This concept of self regulation in an open-market framework through the trading of carbon credits is similar to the concept behind many programmes that exist in the European Union. In Europe and Japan, numerous regulations that address reduction, reuse, and recycling in IT-related operations have been developed. In Europe, the Restriction of Hazardous Substances Directive is one of the most mature programmes with implications for IT manufacturers. The design of this program is similar to regulations developed by Japan’s Ministry of Tourism, Trade, and Industry (MTTI). Myriad public and private efforts are now directed at addressing the broad range of concerns related to global climate change. Clear leadership is emerging within the IT industry, which is positioned very well to maximise the benefits of existing technology while investing in future green technologies. To this end, venture capital spending in the Silicon Valley directed at green technologies doubled from 2005 to 2006. As data centres add, move, and change servers, many on a daily basis, they need to continue to monitor and manage heat generation and cooling requirements. Solutions have to be provided for managing energy usage of data centres over the long term to achieve maximum energy efficiency. It is important to investigate how IT equipment energy consumption varies with computation loads and develop quantitative metrics. There is a strong need for the refinement of already available metrics and measurement protocols for benchmarking servers. A data centre-wide efficiency calculation can be approached in several ways. If the calculation is to be performed in house, it must include the facilities department to address all equipment that support (even fractionally) the data centre’s operations. Many IT professionals opt to obtain expertise through professional service organisations and consulting engineers, because most IT operations do not have the necessary skill sets. Several metrics exist today that can help determine how efficient an operation is. These metrics apply differently to different types of systems: for example, facilities, and network, server, and storage systems. For instance, Power Usage Effectiveness (PUE) and Data Centre Effectiveness (DCE) metrics are the most popular data centre metrics available, and are being accepted by most data centre managers.

384

M. Uddin and A.A. Rahman

4.1.6 Shrinking data for energy efficiency Energy consuming storage arrays are taking centre stage in data centres. When data centre energy is cheap and plentiful, then the power needs of dense disk storage systems are not an issue, as their high energy and cooling costs are easily absorbed into the budget. And when data centre space is not at a premium, the real estate requirements of large tape libraries are not a great concern. But with the high cost of power and cooling and the spectre of data centre build outs and tapped out power grids, building storage behemoths quickly becomes unworkable. Even choosing to deploy many smaller storage systems instead of a few large ones is not any help by itself, because the numerous storage systems simply add up to similar budget-bruising energy and cooling costs. Yet, there is no stopping the flow of data that the enterprise must store. Large-scale data deletions can be disastrous in the face of compliance and litigation demands, and migrating all aging data to tape for offsite storage might be fine for disaster recovery, but makes fast recovery and online access impossible. In response to these pressures, larger amounts of data are sitting on primary storage or migrating to disk-based archives, and that means constantly growing storage capacity and attendant power draws. We believe that the severity of the energy challenge requires an equally strong response. This response takes the form of innovative software technologies to lessen the demand for storage capacity. Many of these technologies are already available to the energy hungry data centre. In fact, secondary storage is already ahead of the game with 20x reduction rates using today’s technologies. Primary storage has lagged behind, but is starting to display energy-related gains using innovative technologies to compress data on the storage systems. This alone will provide the serious data reductions needed to control energy issues around storage, while at the same time improving overall storage utilisation throughout the data centre. Key technologies for green storage include data de-duplication, thin provisioning, primary compression, storage virtualisation and storage tiring. Among these, data de-duplication and thin provisioning hold out some of the strongest hope for slashing energy costs and avoiding data centre build out.

4.1.6.1 Data de-duplication Data de-duplication, or data de-dupe, is a keystone technology for automatically storing single instances of data instead of endlessly housing redundant information. This is a green technology because the less stored data a storage system must house, the more its power requirements and heat generation dwindle. Less data also lets data centres avoid additional storage purchases and eventual build out. The concept of data de-dupe is dead simple: since regular backups dump large amounts of duplicated data onto the storage device, IT should use a technology that strips out duplicated data, ideally to the sub-file level. The result is massive capacity savings and attendant energy savings. De-duping is just as important in virtual environments as in physical counterparts. The ease of creating virtualised backups contributes to explosive storage growth in virtualised environments, which threatens the consolidation gains from virtualising servers. The space savings from de-duping are startling: de-duped backups are up to 100 times smaller than normal backups that have not been de-duped, and data compression can double this number. Multiply this space savings by an untold number of backups and compare the result to shrinking storage needs. The resulting savings in power and cooling is dramatic,

Techniques to implement in green data centres

385

with tens to hundreds of thousands of dollars saved every year. For the purpose of the green data centre, shrinking storage capacity so dramatically is a fundamental solution to storage energy woes. This is why de-duping figures so heavily in the ability to shrink backup storage needs and consequently storage energy demands.

4.1.6.2 Thin provisioning Thin provisioning allows ITs to allocate more storage space to an application than is physically available. Thin provisioning controls over provisioning by satisfying large allocation demands with adequate but smaller physical capacity. Thin provisioning is crucial to achieving high energy savings on primary block storage. The reality of the data centre is that end users or applications often request a great deal more storage than is in fact needed in the near future. The practice is understandable; if an end user is budgeted to purchase new storage, then they will want to spend up to the amount of their budget or risk losing the money in the next budget round whether they need the capacity or not. Another concern is for critical applications and databases, which must never run out of storage space. However, the result is rampant over-provisioning. Over-provisioning occurs when IT provides far more storage than users or applications actually need within a reasonable time period. The upshot of this all too common practice are pitiful utilisation rates of 20% and less, leaving 80% and more of storage taking up space on the data centre floor and consuming power and cooling capacity. This is where thin provisioning demonstrates its worth. Thin provisioning works by allowing data centre managers to allocate a larger virtual amount of capacity than the actual physical amount available. For example, data centre manager might virtually provision 100 GBs to an application, while in fact physically provisioning only 10 GB in the storage pool. As data grows and needs more physical space, thin provisioning can automatically release physical storage chunks. Data centres can set capacity alerts so that if capacity limits are reached, additional storage capacity can be made available. Since thin provisioning decreases over-provisioning and increases disk utilisation, it is extremely effective for reducing over-allocation and accompanying energy costs.

5

Best practices for energy efficient data centres

The last section of this paper provides a description about best practices for green data centres taken from the inputs from field studies and recommendations by various vendors, and should be adopted and implemented for designing and managing green data centres. They provide consolidated dissemination of various aspects of designing efficiency into data centre operations in creating economical and ecological IT infrastructure in data centres. These practices should be followed by data centre mangers to increase the utilisation of already installed devices and reduce the consumption of energy. They also help in achieving green environment-friendly data centres by reducing the emission of GHG. Some of the practices to be followed are explained in Table 3.

386 Table 3

M. Uddin and A.A. Rahman Best practices for energy efficient data centres

Practice

Description

Effects

Regular utilisation audits

1 Perform a manual or ideally automated analysis of server, storage, network, and facilities utilisation rates

1 Data centre operations team can set utilisation rate benchmarks

2 Identify optimisation points as defined by low efficiency rates (low to be defined by operation)

2 Audits identify optimisation points that can open power capacity and set efficiency benchmarks

Take advantage of the reach and intelligence of an IP-based network to complement or replace older analogue networks

1 This practice offers more visibility into the supporting facilities, enabling better decisions

1 Develop better working relationships between facilities and IT

1 Organisational transformation means fewer wasted planning cycles because facilities input is incorporated earlier in the solutions assessment

2 Hire Facilities professionals on the IT payroll

2 The skill base for efficiency planning and analysis is increased

Establish a Change Advisory Board (CAB) to govern efficiency benchmarking, vendor management, skill set dependencies, project funding, and internal and external communications

1 Governance focuses resources on Increasing efficiency in data centre operations

Bringing non-IT assets onto the Network

Organisational Transformation

Governance

2 This practice allows for monitoring, measurement, and management of the largest power-consuming components

2 Governance identifies and articulates gaps in skilled analysis and planning 3 Budget, communications, and reporting can be managed effectively 4 Governance provides regular consolidated reviews of new technology and sets purchasing guidelines

Measurement, monitoring, and Management

1 Standardise on metrics and management applications

1 Managers can include real data on power consumption, efficiency, and emissions in decisions, trending, and reporting

2 Implement network-based management applications across IT and non-IT assets

2 Predictive failure and capacity analysis is possible

3 Integrate network management with server, storage, and facilities management Applications

3 Asset management, provisioning, and component availability are improved

Techniques to implement in green data centres Table 3

387

Best practices for energy efficient data centres (continued)

Practice

Description

Effects

Power profile analysis

1 Develop power profiles per component, system, and service across the existing infrastructure

1 Power and cooling characteristics are added to new and existing operational profiles, including efficiency and corresponding emissions

2 Benchmark power characteristics and apply standards for new services and infrastructure

2 New internal standards are set for procurement, planning, and design of IT services that incorporate power consumption and efficiency

Using internally developed standards (today), assign a green score to existing and proposed data centre projects

An organisation’s decision makers can consider new, crucial data that can decrease expenses and support strong environmental stewardship

Green scoring

6

Conclusion

In recent years, energy efficiency has emerged as one of the most important design requirements for modern computing systems, such as data centres and clouds, as they continue to consume enormous amounts of electrical power. Apart from high operating costs incurred by computing resources, this leads to significant emissions of carbon dioxide into the environment. For example, currently IT infrastructures contribute about 2% of the total global CO2 footprints. Unless energy-efficient techniques and algorithms to manage computing resources are developed, IT’s contribution in the world’s energy consumption and CO2 emissions is expected to grow rapidly. This is obviously unacceptable in the age of climate change and global warming. In today’s IT world, there is an ever increasing demand for online services, leading to increase in demand for IT resources like servers and storage which are hosted in an IT data centre. This further leads to an increase in the demand for power, cooling, space and cabling requirements to host these IT resources. Traditional data centre design techniques cannot cater to these ever increasing, unpredictable demands. This paper focuses on the implementation of a green data centre which efficiently utilises power, space and cooling infrastructures and has the kind of modular, flexible and scalable architecture needed for achieving green status. Different techniques like consolidation, virtualisation, data de-duplication, green metrics, flexible, scalable and repeatable power, cooling and cabling design are proposed to help data centre managers to design and implement green data centres.

References Belady, C.L. (2007) ‘In the data center, power and cooling costs more than the IT equipment it supports’, Electronics Cooling Magazine, Vol. 13, No. 1, February, pp.24–27. Benjamin, K.S. and Marilyn, A.B. (2010) ‘Competing dimensions of energy security: an international perspective’, Annual Reviews, Environmental Resources, Vol. 35, pp.77–108, DOI: 10.1146/annurev-environ-042509-143035.

388

M. Uddin and A.A. Rahman

Cisco (2007) Energy Efficient Data Center Solutions and Best Practices, July, http://www.cisco. com/en/US/solutions/ns708/networking_solutions_products_genericcontent0900aecd806fd32e .pdf Daim, T., Justice, J., Krampits, M., Letts, M., Subramanian, G. and Thirumalai, M. (2009) ‘Data center metrics an energy efficiency model for information technology managers’, Management of Environmental Quality, Vol. 20, No. 6, pp.712–731. Dragovic, B.P., Fraser, B., Hand, K., Harris, S., Ho, T., Neugebauer, A., Pratt, R., Warfield, I. and Xen, A. (2003) ‘The art of virtualization’, Proceedings of the 19th ACM Symposium on Operating Systems Principles (SOSP’03), Bolton Landing, NY, October, pp.164–177. EPA (2007) Report to Congress on Server and Data Center Energy Efficiency – Public Law109-431, Environmental Protection Agency, Washington DC. EPA (2009) EPA Energy Star Program Requirements for Computer Systems – Draft 4, Environmental Protection Agency, Washington, DC. EPA’s (2008) Energy Efficiency in Data Centers: Recommendations for Government-Industry Coordination, US National Data Center Energy Efficiency Strategy Workshop, 8 July–16 October, http://www1.eere.energy.gov/industry/saveenergynow/pdfs/data_center_ wrkshp_report.pdf Gartner (2008) Sustainable IT, A Gartner Briefing, Gartner, Dublin. Green Grid. (2009) Using Virtualization to Improve Data Center Efficiency, Available at: www.thegreengrid.org/ (accessed February 2009) Holusha, J. (2000) E-Business Alters ABC’s of Real Estate, 3 September, 2000, New York Times and Angel, J. (2001) Emerging Technology: Energy Consumption and The New Economy, January 5, Network Magazine. IBM (2008) Energy Management White Paper on Realizing the Value of the Green Data Center by Integrating Facilities and IT, May, ftp://ftp.software.ibm.com/software/in/info/green/ gmw_14011_usen_00.pdf Info-Tech Research Group (2008) If You Measure It, They Will Green: Data Center Energy Efficiency Metrics, Info-Tech Research Group, London. James, M.K., Forrest, W. and Kindler, N. (2008) Revolutionizing Data Center Energy Efficiency, McKinsey & Company, July. John, A.L. (2000) SPS/Spectrum Economics, Global Economic and Information Technology Market Forecasts, 2000–2005, September, As cited in Laitner, J.A., ‘Skip’, Koomey, J.G., Worrell, E. and Gumerman, E. (2001) US EPA and Lawrence Berkeley National Laboratory, Re-Estimating the Annual Energy Outlook 2000 Forecast Using Updated Assumptions about the Information Economy, Presented at the American Economic Association, January 7, New Orleans, Also available as LBNL-46418. Kathan, D. and Thomas, J.G. (2001) ‘Internet data centers: demands for electricity proceed unabated’, Broadband Wireless Online, Part 2 of 2, June–July, Vol. 2, No. 6, Accessed 18 October, at http://www.shorecliffcommunications.com/magazine/volume.asp? Vol=16& story=164 Koomey, J.G. (2007) Estimating Total Power Consumption by Servers in the US and the World, Lawrence Berkeley National Laboratory, Berkeley, CA. Mitchell-Jackson, J.D. (2001) Energy Needs in an Internet Economy: A Closer Look at Data Centers, May 16, Master’s Thesis, Energy and Resources Group, University of California. Berkeley, California, Available at http://enduse.lbl.gov/Projects/InfoTech.html Molla, A., Cooper, V.A. and Pittayachawan, S. (2009) ‘IT & eco-sustainability: developing and validating a green IT readiness model’, Proceedings of International Conference of Information Systems, December, Phoenix, AZ, pp.15–18. Mueen U. and Azizah A.R. (2010) ‘Server consolidation: an approach to make data centers energy efficient & green’, International Journal of Scientific and Engineering Research (IJSER), Vol. 1, No. 1, pp.6–12.

Techniques to implement in green data centres

389

Murugesan, S. (2010) ‘Making IT green’, IT Professional, Vol. 12, No. 2, pp.4–5, March–April, doi:10.1109/MITP.2010.60. Newcombe, L. (2009) Data Center Energy Efficiency Metrics, http://www.bcs.org/upload/pdf/ data-center-energy.pdf Rasmussen, N. (2006) Implementing Energy Efficient Data Centers, American Power Conversion, APC. The Climate Group and the Global e Sustainability Initiative (2008) CO2 Emissions, Carbon Foot Print, Smart 2020, http://www.gesi.org/LinkClick.aspx?fileticket=cOArprYnXWY% 3D&tabid=60