Patent ID: 8051327

Claim:
A data center comprising: a plurality of power distribution units that distribute power from an upstream source; a first group of machines, each of the machines having a first power cord and a second power cord, the first power cord and second power cord of a given machine being connected to two separate ones of said power distribution units, said first group comprising a first machine and a second machine, said first machine and said second machine each being connected to a first power distribution unit, said first machine also being connected to a second power distribution unit, said second machine also being connected to a third power distribution unit that is not said second power distribution unit; a first uninterruptable power supply to which said power distribution units are connected; and a second uninterruptable power supply to which said power distribution units are connected, each of said power distribution units distributing power from either said first uninterruptable power supply or from said second uninterruptable power supply based on whether power from said first uninterruptable power supply fails or has dropped below a threshold level, said second uninterruptable power supply being connected to a plurality of groups of machines other than said first group of machines, each group of machines having its own uninterruptable power supply other than said second uninterruptable power supply, said first group of machines and said plurality of groups of machines sharing said second uninterruptable power supply as their single reserve uninterruptable power supply in an event that a group's own uninterruptable power supply fails.