A typical power system for a data center includes several, possibly hundreds, of circuit breakers connecting data center power sources to computer systems. In certain situations, such as at installation or for performing maintenance on a computer system, it is important to know the computer system-to-breaker mapping and the rated current, actual current, and/or volt-ampere draw of the computer systems to prevent a circuit breaker from being overloaded. For example, the computer system-to-breaker mapping is needed to allow a system administrator to turn off power to a given rack housing the computer system when service of the rack power supply is required or when the rack is being relocated.
The mapping and the rated current, actual current, and volt-ampere draw are also needed for capacity planning, such as to prevent overloading a circuit or power distribution unit (PDU) when connecting computer systems to the circuit or PDU. Capacity planning encompasses two issues. First, when a computer system needs to be connected to a circuit supplying power to the computer system, such as when the computer system is installed or relocated, the system administrator must ensure that there is sufficient capacity available in a circuit to meet the power needs of the computer system. Second, for reliability, an uninterruptible power supply (UPS) unit connected to the circuit and computer system must be sized so that the UPS can supply the load demanded by the computer systems connected thereto when the main power supply to the data center fails. Thus, before a computer system is connected to the data center's electrical grid, it is important for the system administrator to determine whether there is sufficient unallocated power capacity (UPC) available.
In today's data centers, computer system-to-breaker mapping is determined and maintained manually. Typically, each circuit is labeled as it is installed with the PDU number and associated breaker number. When a computer system is subsequently installed, the system administrator records the label information along with the computer system information, for example, in a database. In a data center with hundreds if not thousands of computer systems, this procedure is costly and highly susceptible to error. Furthermore, this process has to be repeated with every change to the data center configuration, such as when new computer systems are added or old computer systems are replaced.
In addition, in today's data centers the current being drawn from a circuit is measured in various ways. However, there is no automated process for correlating a measured load with the computer systems drawing the current. In addition, there is no automated process for aggregating the rated load of the computer systems connected to each circuit. Rated load is important because the actual load of the computer systems is not necessarily representative of the maximum load the computer systems may draw. Hence, the measured load may not be sufficient.