The units will be assembled entirely from commercially available components. A single person should be able to build a unit within four working days. The servers will be stacked in rows, sandwiched between air intake and output vents.
For cooling, ambient air can be sucked in one side, run through the servers and exhausted out the other, with some of the air recirculated to even the overall temperature of the unit. No mechanical cooling units will be used. Networking and power buses will run over the tops of the servers.
The construction materials rely heavily on steel and aluminium, both easily recyclable. The water requirements can be met by a single hose with residential levels of water pressure, he said.
The development team considered different sizes of containers, Timmons said, keeping an eye toward making the units easily shippable. They settled on a size that could contain 1,200 to 2,100 servers and draw between 400 and 600 kilowatts.
The units can be placed inside a large building, or when equipped with outer protective panels, reside out in the open.
One of the chief requirements of IT PACs, he admitted, is that they reside in an area where the ambient temperature is mild enough that it can provide sufficient cooling. Because of their highly portable nature, this should not be a problem, he said.
"If we're doing our job right in site election, square footage will be cheap for me. I want to find a place with lots of room to expand. I don't want to worry about a watts-per-square-foot problem. I'd like to worry about having enough acreage," he said. "We're doing a good job in site selection when we don't have to squeeze in 500 watts per square foot."
Due to their minimal use of mechanical cooling, Timmons estimated that the PUE ratio for its IT PACs would be 1.26 to 1.35, depending on the outside conditions. PUE, or power usage effectiveness, compares overall power supplied to the data center against the amount that actually reaches IT equipment.
A typical data center PUE is around 2.1, according to industry estimates.
If the IT PACs are ultimately pushed into production, Timmons said he hasn't fully decided if Microsoft will build them itself or contract them out. It would probably be a mix of the two, he predicted. "I know how much it costs to build one of these now," he said.