From Joel Hruska’s “The Beast unveiled: inside a Google server” (Ars Technica: 2 April 2009):
Each Google server is hooked to an independent 12V battery to keep the units running in the event of a power outage. Data centers themselves are built and housed in shipping containers (we’ve seen Sun pushing this trend as well), a practice that went into effect after the brownouts of 2005. Each container holds a total of 1,160 servers and can theoretically draw up to 250kW. Those numbers might seem a bit high for a data center optimized for energy efficiency—it breaks down to around 216W per system—but there are added cooling costs to be considered in any type of server deployment. These sorts of units were built for parking under trees (or at sea, per Google’s patent application).
By using individual batteries hooked to each server (instead of a UPS), the company is able to use the available energy much more efficiently (99.9 percent efficiency vs. 92-95 percent efficiency for a typical battery) and the rack-mounted servers are 2U with 8 DIMM slots. Ironically, for a company talking about power efficiency, the server box in question is scarcely a power sipper. The GA-9IVDP is a custom-built motherboard—I couldn’t find any information about it in Gigabyte’s website—but online research and a scan of Gigabyte’s similarly named products implies that this is a Socket 604 dual-Xeon board running dual Nocono (Prescott) P4 processors.