Clustering

Power and Cooling

Cluster Power & Cooling requirements.

The first thing you need to consider before installing and building a cluster is the power and air conditioning requirements for it. when you are working with one to four computers this is not a problem, because most AC and power systems can support this amount of computers as soon as you go above 4 computers it is time to begin considering power and AC requirements. first the background information that you will need.

Power requirements per node.
1. This can be obtained by the manufacturer.
2. as a rule of thunb a computer will convert almost all of its power requirement to heat.
Maximum amperage per circuit.
1. In most houses this can range from 5 ~ 15 amps
2. some institutions may carry 20 amp circuits.
Rack instalation type.
1. Size of server units.
2. Maximum nodes per rack.
3. This become important in the power delivery stage.
Room size and layout.
1. Distance from outside.
2. rectangular or square

Power and Cooling Calculations.

For this example i will be using the Dual 2Ghz Xserve cluster node, 20 amp circuits, and a rectangular room in the middle of a building for the calculations and examples.

Each Xserve uses 300 watts of power and ocupies 1U of rack space

Here is a method to determin the circuit requirements for a cluster.

Here is an example calculation for a 64 node Xserve cluster

Next the cooling requirements need to be mapped out. In air conditioning 1 ton of cooling is able to manage 3,500 Watts of heat. To determin the cooling requirements for a cluster you can use the following equiation.

Here is an example calculation bassed on a 64 node 300 Watts/node system

Now that we know how much cooling we will need its time to determin the power delivery system and, cooling system.

Power Delivery System.

Under normal situations power Delivery systems are not something you would have to think about but when you have 32 nodes that ocupy 1 48 node rack desity and delivery become an important issue, there are many comanies that have power management and delivery systems for racks but i decided to design my own system. here are the basic specs of it.

Here are some pictures of the final design ( The picture has been flipped horizontaly )

The Rack that was used for this system is the APC 42 unit vx model with extra space for the power supplies.

Cooling Considerations

If you are lucky enough you will allready have adequate cooling in the target room for the cluster, if not, it is neccesary to install your own cooling system here was the cooling system used for our cluster.

Most likely you will contract this out to an HVAC company, With a word of caution i would like to warn you to make sure that the HVAC people know where you want the cold side to be, do not assume that they know.

Eric Adint