Delivering Airflow Efficiently for the Cloud
December 14th, 2010 By: Industry Perspectives
Daniel Kennedy is the Data Center Product Manager for Tate Access Floors.DANIEL KENNEDY
The high rate of adoption of cloud computing over the past few years has been driven by the need for on demand computing to meet everyday business needs in the most efficient method possible. Cloud computing, both public and private, can bring with it difficulties that may not have existed previously in the data center environment.
In the past, the load profile per rack was typically considered to be relatively stable, in terms of energy consumption and heat production when viewed on a daily, weekly or monthly basis. This was primarily a result of low hardware utilization due to dedicated tasking of each individual server. The only changes that the data center operator needed to handle in terms of electrical distribution or airflow distribution came during moves, adds or changes.
Variable Cloud Computing is a Game-Changer
Cloud computing is changing this stable load environment. This change can increase efficiency, as now IT hardware can be utilized at a much higher level since it exists as a component on the cloud, allowing for maximum utilization of its hardware components. The scalable cloud can allow for computing resources to be brought online as required by demand to realize the efficient complete utilization of the hardware.
This progress, however, may complicate the power and airflow provisioning aspect of the data center environment. For the most part, power provisioning is automatic. The server demand for electrical power scales with relatively even efficiency from very low utilization to peak utilization with no intervention from the user. Electrical losses in transformers, and in UPS systems are daily occurrences and have been addressed by those hardware manufacturers, either through a reduction in transformer steps (e.g. 415V distribution, DC distribution) or optimization of the internal designs (e.g. rotary UPS Systems, Online/Hybrid Conventional UPS units.)
Optimizing Airflow in the Data Center
Efficient airflow distribution, however, must be considered. Typical raised-floor cooling designs can only allocate airflow based on the panel design. Increasing panel open areas, the use of manual dampers and other products do allow the data center operator some individual, rack level control, but this is only adequate for handling load diversity (different rack loads within the same cooling infrastructure). These products are incapable of handling continuous load profile changes on a per rack basis. The use of variable-speed fans at the air handling equipment level is a common approach as well, but typically this approach falls short of the granularity of control that cloud computing requires for efficient airflow distribution.
Aisle level containment, or rack level containment, is another potential strategy used for airflow control, but these approaches may have drawbacks for individual sites (e.g. available floor space, hot aisle temperatures, lack of drop ceilings, fire suppression code) and for the data center operator with multiple facilities worldwide, using different design approaches from data center to data center increases management complexity.
Controlling Airflow is Critical
The key to success in this environment is the ability to control the amount of air and directly match it to the air flow requirements of the IT hardware that exists in the data center at any given moment in time. Directional airflow, to the equipment can provide superior cooling capabilities to vertical airflow distribution. At the same time, the amount of air required at each IT rack on the cloud, should be closely controlled to ensure adequate airflow based on the current demand. This allows the data center operator to ensure that the cooling infrastructure deployed in the data center is used efficiently. This approach can remove the requirement for aisle/air containment at the row or rack level through the creation of a virtual aisle containment solution that significantly reduces by-pass air by constantly adjusting the amount of airflow on a per rack basis based on demand.
This configuration also allows the data center to realize the efficiencies gained by using larger, more cost effective central cooling systems. Eliminating the need to adopt rack or row level cooling solutions, and the potential risks and inefficiencies these systems bring to the table.
Meeting the Needs of the Cloud is the Current and Future Challenge
Cloud computing is the way forward for efficient and highly available computing. The data center operator will be faced with new challenges that cloud computing may bring to the day-to-day operation of their data center cooling infrastructure. The efficiency minded data center operator should ensure that their cooling infrastructure has been designed with these advances in the IT market in mind.
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