In 1973, at the peak of the global energy crisis, when oil prices reached their maximum value, Western governments were forced to adapt to new economic conditions. Thus, the crisis was the starting point of the energy adjustment. In the same period, comprehensive national programs were adopted to promote the energy efficiency in developed countries. At the moment, data centers are the largest consumers of electricity, and they will remain so in the near future. They consume about 2% of the total electricity produced in the world. Data centers are increasingly faced with the problem of thermal energy – side heat from the tightly integrated racks of servers. Nowadays, about $ 24.7 billion is consumed on power and cooling of unused server systems in the data centers every year. This is about 15% of the servers in the data centers that are idle and still consume electricity. The average annual energy cost of the server with 400 watt power supply is about $ 800. It quickly became apparent to data center operators that the reduction of electricity used for industrial purposes would not only reduce the amount of bills from power companies, but also enable the use of the released capacity for commercial purposes. This was important for many regions with a serious shortage of electric power.
Energy is one of the main expenditure items of business. It occupies the first place in the budget of companies whose business is based on the data centers (for example, Google and eBay). Leaders of companies are concerned that the cost of electricity, which increases sharply with extension of the data center capacity, could hinder current operations and further development of the business. At the same time, according to some analytical reviews, carbon dioxide emissions from electricity production for the needs of data centers on a global scale are equal to emissions of a country like Argentina, the twenty fourth largest economy in the world.
Advantages of Green Data Centers
In this light, green data centers are one of the key technology areas. Using the phrase “green technology” does not mean the transition to clean energy, such as solar or wind ones. The term “green” means the use of the least energy-consuming process in the operation of devices, ensuring their maximum performance. This term became commonly used among professionals in the field of data centers. Increased energy productivity of systems is a key factor to reduce power costs and neutralize the environmental damage from the operation of data centers. Enterprises understand the close relationship between environmental safety and efficiency of data centers. Green data centers help not only save the environment, but, at the same time, which is especially important for business, save big money. Thus, they help solve two major problems. It is also important that the leading groups of companies in the data center industry understand the problem and fight against it together.
Role of the Servers’ Size
Reduction of the physical size of servers does not reduce the power requirements of cooling systems of data centers. The widespread transition to compact high-performance systems, including modular, comprising a plurality of processor cores, greatly increases the power of both individual racks and data centers. The growth of density of the equipment poses more challenges for manufacturers of cooling systems and data center designers. Today, a standard server rack can dissipate 24 kW or more, and the power of the largest data centers reach a few megawatts. The vast majority of energy-intensive data centers are located in big cities and often in the central part of the city.
The use of secondary energy evolved by equipment of data centers becomes more and more widespread. Recently, a Finnish company Academica announced the construction of a large data center located in an underground cave. The use of cold air inside the cave to cool the data center will reduce the cost of its maintenance. However, that is not all. The thermal energy generated by the installed equipment will be sent to the municipal heating system. The most progressive way to minimize the cost of cooling the data center is to use cold outside air. To solve this problem, water or glycol chillers with free cooling function containing a special heat exchange unit, where the coolant heated in the indoor unit is cooled with outside air, are needed. The use of such systems allows data centers to abandon the compressor to cool the refrigerant for almost whole year. Implementation of new technologies to reduce the processor’s speed can significantly save energy. In addition, the automatic shutdown of the peripherals that are not needed during the processor’s work, also leads to significant savings of electricity. There is often a duplication of the same information in different disk arrays, when storing information in large servers. This is a very energy expending operation, which leads to the high consumption of electricity. That is why, for greater energy saving, it is advisable to use such method of storing information as deduplication. Deduplication significantly reduces energy consumption, simultaneously fulfilling qualitative duplication of large amounts of information on the server. Such leading companies of computer hardware as HP Blade System, IBM Blade Center, SUN Blade, ESC Blade, as well as many others, use this technology to reduce energy consumption in their products.
In addition to conventional air cooling, the water cooling of the server can be used. The water cooling can reduce power consumption. This technology significantly reduces energy consumption compared to air cooling. However, the complexity of the design, installation and operation allows the usage of a water cooling system not in all cases. The technology HP Dynamic Smart Cooling (DSC) is a real godsend. This technology reduces the use of special temperature sensors that produce diagnostics and transmission of information on the regulation of air conditioning systems. DSC technology is perfect for solving the task of reducing power in the server. Dynamic regulation of airflow can multiply the effectiveness of the forced-air cooling. Of course, DSC technology is not the only technology that reduces power consumption of the server. IBM Corporation offered its users a set of server power supplies (IBM Cool Blue), which is equipped with an improved ventilation system inside the rack and equipment Calibrated Vector Cooling. Dynamic connection and disconnection of control and automation systems provides optimal performance of these systems. Automatic connection and disconnection of the equipment at the specified time and rigging facilities with the timer repeatedly lowers power consumption and increases the efficiency of the specific server.
Virtualization and DPM
The usage of such technologies as virtualization and VMware Distributed Power Management (DPM) promotes the consolidation and reduction of the number of the server hardware in a particular organization. These technologies also allow more efficient usage of the storage area network (SAN). The effective use of server hardware, and even distribution of the load on the various virtual machines (using technology DPM), allows not to use the additional server hardware, which does not have the functional load.
Climate Control Measures
The climate control is a complex of measures aimed at creating and maintaining an optimal climate for the given process, as well as its monitoring and control. For data centers, these measures are implemented through the ventilation system, air conditioning and humidification, which help to control the level of temperature, humidity and dust in the room.
In conclusion, the global economic and financial crisis and the high price of electricity encourage owners of data centers to think about possible ways of reducing energy consumption. Thus, they tend to use green technologies in their data centers.