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Design Considerations for a Green Data Center

Manish Sethi outlines seven steps to paint your data center green

IT departments are under increasing scrutiny and pressure to deliver environmentally sound solutions. Large data centers are one of the most significant energy consumers in an organization’s IT infrastructure, so any measures that you can take to reduce this consumption (and therefore also carbon dioxide emissions) will have a positive impact on your organization’s environmental footprint.

Gartner reveals that during the last five years, the power demands of equipment have grown by five or more times. Additionally, a report issued by the Environmental Protection Agency in US indicates that environmental issues have placed IT departments under pressure to develop ‘green’ data centers.

A green data center is defined as one in which the mechanical, lighting, electrical and computer systems are designed for maximum energy efficiency and minimum environmental impact. The construction and operation of a green data center involve advanced technologies and strategies.

Some examples include:

• Reducing the power consumption of the data center
• Minimizing the footprints of the buildings
• Maximizing cooling efficiency
• Using low-emission building materials, carpets and paints
• Installing catalytic converters on backup generators
• Using alternative energy technologies such as photovoltaic electrical heat pumps and evaporative cooling

The consumption of energy is considered the dominant – and often the only – factor in defining whether or not a facility is green. IT executives therefore need to start investigating alternative ways of building energy-efficient data centers.

By following these seven simple steps, IT executives can come closer to achieving their vision of a green data center:

1. Think green

Environmental concern is the prime focus for the society today, and you can also take a ‘green’ attitude towards your data center, both in terms of current state and also future planning. Also, many data center vendors and service providers are providing green alternatives – factor these options in when negotiating new contracts and planning upgrades. A realistic strategy is necessary that takes into consideration the following aspects when planning a data center:

• The existing utilization rate of your servers, which includes the number of servers in the environment, their average power consumption, the cost to run per hour, the cost to run servers per year, the cooling power consumption and the cooling costs
• The expected data growth of the data center, which includes taking into account future business demands and scenario planning for a world where environmental considerations are likely to become much more demanding.

Incorporate the green vision in your planning – your future will be impacted by legislation, standards and market demands in this area.

2. Virtualize and consolidate

A virtualization and consolidation project is often a step in the right direction towards green computing. Research indicates that a server often only utilizes between 5 and 15% of its capacity to service one application. With appropriate analysis and consolidation, many of these low utilization devices can be combined into a single physical server, consuming only a fraction of the power of the original devices and saving on costs, as well as taking a step towards a more environmentally-friendly data center environment.

The basic concept of virtualisation is simple: encapsulate computing resources and run on shared physical infrastructure in such a way that each appears to exist in its own separate physical environment. This process is accomplished by treating storage and computing resources as an aggregate pool, from which networks, systems and applications can exploit, on an as-needed basis.

Virtualization and consolidation projects are complex, but the benefits are compelling. Server consolidation ratio examples include 15:1 or 45:3, and virtualisation results in improved application availability and business continuity independent of hardware and operating systems, among others.

Whether your main driver for consolidation and virtualisation is to save money, manage risk or reduce your organization’s carbon footprint, make sure it forms part of your plan to be green.

Design a best practice floor plan

The Uptime Institute produced a white paper based on a survey of 19 data centers and reported that, on average, only 40% of the cold air went directly towards cooling the servers in the room, wasting yet more power in the data center. So, whether you are designing a new data center or upgrading your existing environment, make use of existing best practices in data center floor plan designs. Examples include:

Hot aisle/cold aisle layout

Adopting an alternating hot aisle/cold aisle layout is optimal and can correct many cooling problems in a typical data center. By implementing a hot/cold aisle layout, equipment is spared from having hot air recirculated and thereby eliminating risk of an outage through device failure.  Also, by having a common hot aisle, you have the ability to contain areas where heat density is high, such as racks with blade servers, and deal with the heat in a specific manner.  This allows for multiple heat rejection methods to be in use within one data center.

The distribution of power across racks

Another layout consideration is the distribution of power across racks.  All attempts should be made to balance the watts per rack to within a 10-15% variance.  This minimizes hot-spots and the need for sporadic hot-aisle containment. Often data center designers locate servers performing related functions in the same racks, but the benefit of having these servers close together is outweighed by the heat density this may cause.

Minimize or eliminate under-floor cabling

It is imperative for organizations with static pressure cooling to minimize or eliminate under-floor cabling. If you can’t avoid it, use conduit, cable trays, and other structured methods for running cabling. This minimizes barriers between computer room air conditioning (CRAC) units and perforated tiles, resulting in more efficient air flow and optimized cooling system efficiency.

Don’t underestimate the importance of the physical design of the data center when it comes to power and cooling, both for sustainability, costs and environmental impact.

4. Use appropriate technology

In taking a green approach to your data center, your evaluation of products is no longer just a price versus performance comparison. It is important to incorporate the total costs of the environment into the calculation, which then also includes costs for energy consumption.

Firstly, look for vendors that have power and cooling at the forefront of their research and development strategies. Secondly, select equipment based on life cycle costs that take into account the energy usage of servers.

An example of a green technology is MAID (Massive Array of Idle Disks). This is a storage technology that employs a large group of disk drives in which only those drives in active use are spinning at any given time. This technology can have thousands of individual drives, and offers mass storage at a cost per terabyte roughly equivalent to that of tape.

Make sure you use suitable technology and product to become green. More importantly, use the technology and products you choose appropriately through configurations and by enabling green controls, to truly maximize the green effect.

5. Take a green perspective on ILM

Information Lifecycle Management (ILM) is the optimum allocation of storage resources that support a business. Every element of information in an organization has a useful lifespan, and this can range from a voice conversation to certain legal and medical records. By implementing an ILM strategy, you have the ability to create greater efficiencies in data storage, which in turn lead to greater efficiencies in elements such as power consumption.

ILM is the application of rigor to the often chaotic and unstructured data stores that an organization maintains. The storage, utilization, maintenance and destruction of this data can be quite expensive over its lifetime and, what is worse, its lifetime is often much longer than its useful life. The art of ILM is to develop an understanding of an organization’s information needs, and to develop the infrastructure and processes required to maintain the usefulness of the information, while at the same time creating the discipline to minimize the cost of that maintenance.

Tiered storage is at the heart of an ILM implementation. The value of ILM is the ability to tie the cost of storage to the value of the information on it. The most important data, or the most performance-critical data, should be placed on the highest performance and most expensive storage. In turn, do not use expensive energy-consuming servers to store information for compliance, when a tape will do.

Additionally, knowing the character (age, file type, usage frequency, and business value) of the data in your environment is pivotal for being able to make informed decisions around ILM strategies. Assessments that Dimension Data has conducted with more than 100 organizations worldwide show an average of more than 40% file duplication* in their environments. With this information, organizations have the knowledge to decide whether to move data to less expensive and energy consuming storage, and to better utilize their existing environment and save storage space.

6. Investigate liquid cooling

To meet the challenges of blade servers and high-density computing, more organizations are realizing the need for effective cooling and heat management solutions. Many are welcoming liquid cooling systems into their infrastructures to achieve better cooling efficiency, while others may find it difficult to fathom pipes of running water snaking through the plenums of their data centers.

In essence, liquid cooling systems utilize air or liquid heat exchangers to provide effective cooling and isolate equipment from the existing HVAC (heating, ventilating and air conditioning) system.

There are several approaches to data center liquid cooling:

• Sidecar heat exchangers - these are closed enclosures that deliver cooling from the side, which keeps the cooling from dissipating into the server room
• Chip-level cooling and bottom mount heat exchangers - these enclosures use a bottom mount heat exchanger which some claim is safer than sidecar enclosures as components won’t be affected in the event of a water leak
• Modular liquid cooling units - these units are used within a fully sealed cabinet and are mounted at the rack base, in a rack sidecar
• Door units - full-door units replace a standard server rack door and contain sealed tubes filled with chilled water
• Integrated rack-based liquid cooling - these systems incorporate a rack-based architecture that integrates UPS power, power distribution and cooling and feature a cooling distribution unit (CDU) that pumps water through aluminum/plastic tubing to cool servers
• Device-mounted liquid cooling - these solutions work at the device level, with coolant routed through sealed plates on the top of a CPU (central processing unit)
• Review the latest cooling methods for a number of different reasons, but don’t lose sight of the green vision – some liquid cooling systems are not designed with the environment in mind!

7. Utilize greener energy sources

Many energy utilities are now offering greener options for customers, with power from sustainable sources. For example, in the United States, the US Environmental Protection Agency (EPA) has formed the Green Power Partnership, which encourages and assists organizations to buy green power and reduce their impact on the environment. Major economies in Asia have accepted the Kyoto Protocol to control carbon emission however only Japan has committed to a reduction by 2012. The awareness on social responsibility and opportunity to save operational cost has raised the bar on awareness and willingness to adopt a more green approach towards utilities.

There are also some emerging power-saving technologies that are likely to become more commonplace in a data center in the near future. For example, DC-compatible equipment would have a significant impact on power consumption, but it is costly to configure, it is not widely available and it is also more expensive than equivalent AC options.

At present, data centers perform many conversions between alternating current (AC) and direct current (DC). This wastes energy, which is emitted as heat and increases the need for cooling. It would be far more efficient to power servers directly from a central DC supply. The Lawrence Berkeley National Laboratory in the US estimates that an organization may save 10% to 20% of their energy use by moving to direct current technology.

Make sure you utilize the expertise around power that resides outside the IT department in kyour organization – it all forms part of the bigger picture of your plan to be green.

The author is Head Solutions Development Group Datacraft India manish.sethi@datacraft-asia.com