Green Cloud Online

The Green Cloud is now online!

The Green Cloud is the invention of Dr. Paul Brenner at the ND Center for Research Computing. It is a containerized data center located at the South Bend city greenhouse, stocked with used servers kindly donated by Ebay, Inc. The first batch of machines was installed in December, and will eventually reach about 400 cores once everything is turned on.


What makes the data center unique is that is has no air conditioning. Instead, the data center takes in ambient air, and then exhausts it into the greenhouse. This benefits Notre Dame, since we no longer pay the cost of cooling, but it also benefits the greenhouse, which has significant heating costs during the winter months. (We used to call this idea grid heating.)

Of course, this means the capacity of the system may change with the weather. During the winter, the system can run at full blast and deliver as much heat as possible to the greenhouse. During the spring and fall, the heat may not be needed, and can be vented outdoors. During the hottest part of the summer, we may need to shut some machines down to get the temperature under control. However, recent studies by big data center operators suggest that machine temperature could be safely increased to 80 or 90 degrees, so there may be a fair amount of headroom available. We will see.

For a normal data center that runs web servers and databases, shutting down machines is not really an option. However, the Green Cloud provides fungible computing power for large computations in science and engineering at Notre Dame. If structured correctly, these workloads can adapt to 10 or 100 or 1000 cores. So, turning machines on and off will affect performance, but not correctness.

A good example of a flexible workload is genome assembly. Two of our students, Christopher Moretti and Michael Olson presented initial results on a Scalable Genome Assembler at the MTAGS Workshop held at Supercomputing 2009. Their assembler uses our Work Queue framework to manage a variable workforce, pushing out sequence fragments to whatever machines are available. The system has scaled up to about 1000 cores, spread across the Notre Dame campus, the Green Cloud, Purdue University, and the University of Wisconsin.

We are currently working on a journal paper and an open source release of the assembler, so stay tuned for details.

Grid Heating: Putting Data Center Heat to Productive Use

Dr. Paul Brenner, a research scientist in the Computing Research Center at the University Notre Dame, has been advocating a novel idea called grid heating. He recently won a "Green IT Award" from the Uptime Institute for his work. Here is a short introduction to the idea:

Around the world, large data centers consume enormous amounts of power. In addition to the energy needed to spin disks and rearrange electrons, an approximately equal amount of power is needed to run the air conditioners and fans to remove that heat from the data center. In this sense, data centers are doubly inefficient, because they are using power to both heat and cool the same space. If we could put that heat to productive use, then we could save energy on cooling the data center, as well as save energy that would have otherwise been used to generate heat.


Last year. Dr. Brenner constructed a prototype of this idea at the city greenhouse in South Bend, which was struggling with enormous heating bills during the winter. He constructed a small cluster, and placed it in the Arizona Desert display in the greenhouse, where the plants need the highest temperature. Notre Dame paid the electricity bill, the greenhouse got the benefit of the heat, and the computers simply joined our campus Condor pool. Everybody wins, and nobody has to pay an air conditioning bill.



However, the first cluster was just a prototype, and couldn't generate nearly enough heat for the entire greenhouse. So, this year, Dr. Brenner is building a small data center in a modular shipping container. next to the greenhouse. With a new electricity and network hookup, the data center will run several hundred CPUs, and function as a secondary furnace for the facility, hopefully reducing the heating bill by half over the winter.

The new facility will significantly add to our campus grid, and will also give us some interesting scheduling problems to work on. The greenhouse needs heat the most during the winter, and to a lesser extent during the summer, so the computing capacity of the system will change with the seasons. Further, the price of electricity varies significantly during the day, so jobs run in the dead of night may be cheaper than those run during the day. If we can connect our "campus grid" to the "smart electric grid", we can make the system automatically schedule around these constraints.

Here are some recent articles about Grid Heating:

• Lowering Heating and Cooling Bills with Flower... er. Cactus Power
• Warm the Cacti, Cool the Computers
• ND Receives Uptime Institute's Green Enterprise IT Award
• Grid Heating Clusters: Transforming Cooling Constraints Into Thermal Benefits