Data Centers of the Future Part IV
This is part 4 of a 4 part series on data centers of the future. Part 4 will be a discussion of future technologies that might help solve some of the existing challenges in supporting high density loads in a data center. Special thanks to EYP and APC for the use of their graphics in this article.
So what are my predictions for the data center of the future? There are few things that can be predicted with certainty, but unless there is some major breakthrough in chip design that allows them to run cooler at the same processing speed, the data center of the future will be cooled by something other than air Whether its chilled water or some other supplemental cooling system remains to be seen, I know, those of you who have worked in data centers long term are cringing. We just stopped celebrating the death of the water cooled mainframe and the problems associated with the plumbing. But if you look long term, we've reached a plateau with air cooled data centers.
Reasonable designs for air cooled data centers can accommodate up to about 6 to 7kW per rack. With diversity in the technologies in use in data centers today, this would accommodate the vast majority of users today. Remember, the average densities in data centers today are still less than 50 watts per square foot or 2kW per rack. However, if large quantities of high density servers ever get installed in a data center, conventional designs cannot accommodate them. The volume of air required to cool them is simply prohibitive. To get beyond these densities, water cooling or some kind of supplemental cooling system will be required. Even data centers of 7kW per rack would need careful planning. Here is an example of a data center that is designed for loads up to 7kW per rack.
Some of the possibilities for data centers of the future include:
Water cooled data centers - EYP-Mission Critical Facilities recently designed two data centers. One was air cooled and one was water cooled. Both have the same processing capability. The water cooled data center requires less than half the square footage of the air cooled model for the same processing capacity.
DC powered data centers - There are several engineering firms working on DC powered data centers. It only makes sense given that computers already run on DC power. We simply convert it from AC to DC using relatively inefficient power supplies. We actually do that several times when you take into account the use of on-line UPS systems. Distributing DC power at a higher voltage would also take care of some of the inefficiencies inherent in 48 volt DC power systems.
Fuel Cells - Fuel cells may become practical as a primary source of power for data centers long term. They have the advantage of being the favorite alternate energy source of both the government and environmentalists and are well funded as a result. Currently however, they are more than 10 times more costly than any of the other realistic alternatives and they have challenges both with fuel storage, frequency regulation and maintenance requirements.
Distributed data centers - Building several smaller data centers and distributing the workload among each is a viable way to minimize the risks associated with having all of your data processing in a single data center. By building in different cities, you could provide regional diversity and protect your company from a regional disaster. You could also oversize each site to allow them to back each other up. Those of us with a background in operations look forward to the day that we could shut a site down for repairs by shifting the workload to the other site(s).
Construction costs - With construction costs for high density Tier 4 data centers approaching and in some cases exceeding $2,000 per square foot, at some point outsourcing becomes and attractive option. This could spur be a real boon to existing collocation data center service providers. This is however, a two edged sword for outsourcers. Most of the collocation data centers out there are not designed to Tier 4 standards and cannot handle loads beyond 100 watts per square foot. A knowledgeable user may find few sites that meet their requirements.
Co-generation may become a common design feature in large data centers if loads reach the levels being predicted. Large high density data centers require tremendous amounts of power. Most utilities don't have these levels of power available and may be years away from being able to supply it. At these densities, depending on the cost of electricity in a particular area, co-gen becomes a viable alternative. Here is an example of the power requirements for large high density data centers and the costs associated with them. This is based on a 50,000 square foot data center, fully loaded to design capacity, .10 cents per kilowatt hour and assumes a one to one ratio between power and cooling.
What is the most likely scenario? I believe that liquid cooling/supplemental cooling systems will become commonplace in data centers of the future. I also think there will be a number of different solutions to try and accommodate high density loads and eventually there will be an almost universally accepted design just like there is today. It may be DC powered, it may be two story, it may involve the use of co-gen or fuel cells. One thing is certain, the densities will continue to go up unless there is some kind of technological breakthrough in chip design. Until that happens, power and cooling will continue to be our biggest design challenge.
Ron Hughes, President of California Data Center Design Group has been involved in the design, construction and operation of data centers for over 25 years. In the last 6 years alone, Ron Hughes has managed the design of over 1,600,000 square feet of data center space in the US, Europe, Asia, the Middle East and Mexico. His firm is currently designing high density data centers with loads ranging from 5 to 25 kW per rack.