Patent Publication Number: US-9852485-B2

Title: Systems and methods for power topology mapping

Description:
TECHNICAL FIELD 
     The present disclosure relates in general to information handling systems, and more particularly to systems and methods for mapping power topology in a data center environment. 
     BACKGROUND 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     In a data center comprising multiple information handling systems, there is often a desire to gather configuration and status information, and create maps from this information to define a complete power and information technology equipment infrastructure or topology of the data center. Having a map of such topology may assist in data center management, allowing removal of guess work in determining a data center&#39;s power needs, reclamation of trapped power, and avoiding unscheduled downtime. 
     Such configuration and status information may include at least two types of data. One type of data is data regarding individual information handling system hardware configuration, such as computing load and power consumption, etc. which may be used to optimize system resource mapping. Another type of data is a physical power mapping between one or more power distribution units and individual power supply units, which may be used for balancing loads on each alternating current phase in order to optimize power sourcing. Existing approaches to such mapping typically involve manual entry of mapping the server rack location and its corresponding power distribution unit and power distribution outlet in a table or other data structure. Such manual data entry may be costly, time consuming, and prone to error. 
     SUMMARY 
     In accordance with the teachings of the present disclosure, the disadvantages and problems associated with mapping of a power topology may be reduced or eliminated. 
     In accordance with embodiments of the present disclosure, an information handling system may include a processor and a non-transitory computer-readable medium communicatively coupled to the processor and having stored thereon a program of instructions. The instructions for may cause the processor to, when read and executed, communicate a first message to a second information handling system such that receipt of the first message by the second information handling system causes the second information handling system to cause a power supply unit integral to the second information handling system to experience a perturbation in an electrical current associated with the power supply unit and receive a second message from a power distribution unit via an outlet integral to the power distribution unit, the second message indicative of a response to the perturbation of a measured electrical parameter of the outlet. 
     In accordance with these and other embodiments of the present disclosure, a method may include communicating a first message to an information handling system such that receipt of the first message by the information handling system causes the information handling system to cause a power supply unit integral to the information handling system to experience a perturbation in an electrical current associated with the power supply unit and receiving a second message from a power distribution unit via an outlet integral to the power distribution unit, the second message indicative of a response to the perturbation of a measured electrical parameter of the outlet. 
     In accordance with these and other embodiments of the present disclosure, an article of manufacture may include a non-transitory computer-readable medium and computer-executable instructions carried on the computer-readable medium. The instructions may be readable by a processor, the instructions, when read and executed, for causing the processor to communicate a first message to a second information handling system such that receipt of the first message by the second information handling system causes the second information handling system to cause a power supply unit integral to the second information handling system to experience a perturbation in an electrical current associated with the power supply unit and receive a second message from a power distribution unit via an outlet integral to the power distribution unit, the second message indicative of a response to the perturbation of a measured electrical parameter of the outlet. 
     Technical advantages of the present disclosure may be readily apparent to one skilled in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
         FIG. 1  illustrates a block diagram of an example system, in accordance with embodiments of the present disclosure; 
         FIG. 2  illustrates a block diagram of an example information handling system, in accordance with embodiments of the present disclosure; 
         FIG. 3  illustrates a block diagram of an example power train, in accordance with embodiments of the present disclosure; 
         FIG. 4  illustrates a block diagram of an example power distribution unit, in accordance with embodiments of the present disclosure; 
         FIG. 5  illustrates a block diagram of an example system manager, in accordance with embodiments of the present disclosure; 
         FIG. 6  illustrates a flow chart of an example method for mapping a power supply unit to a power distribution unit and outlet, in accordance with embodiments of the present disclosure; 
         FIG. 7  illustrates a graph depicting an example current perturbation that may be applied to a power supply unit in order to facilitate mapping of the power supply unit to an outlet of a power distribution unit, in accordance with embodiments of the present disclosure; 
         FIG. 8  illustrates a graph depicting another example current perturbation that may be applied to a power supply unit in order to facilitate mapping of the power supply unit to an outlet of a power distribution unit, in accordance with embodiments of the present disclosure; and 
         FIG. 9  illustrates a graph depicting another example current perturbation that may be applied to a power supply unit in order to facilitate mapping of the power supply unit to an outlet of a power distribution unit, in accordance with embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Preferred embodiments and their advantages are best understood by reference to  FIGS. 1-9 , wherein like numbers are used to indicate like and corresponding parts. 
     For the purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, an information handling system may be a personal computer, a personal data assistant (PDA), a consumer electronic device, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include memory, one or more processing resources such as a central processing unit (CPU) or hardware or software control logic. Additional components of the information handling system may include one or more storage devices, one or more communications ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communication between the various hardware components. 
     For the purposes of this disclosure, computer-readable media may include any instrumentality or aggregation of instrumentalities that may retain data and/or instructions for a period of time. Computer-readable media may include, without limitation, storage media such as a direct access storage device (e.g., a hard disk drive or floppy disk), a sequential access storage device (e.g., a tape disk drive), compact disk, CD-ROM, DVD, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and/or flash memory; as well as communications media such as wires, optical fibers, microwaves, radio waves, and other electromagnetic and/or optical carriers; and/or any combination of the foregoing. 
     For the purposes of this disclosure, information handling resources may broadly refer to any component system, device or apparatus of an information handling system, including without limitation processors, service processors, basic input/output systems (BIOSs), buses, memories, I/O devices and/or interfaces, storage resources, network interfaces, motherboards, power supplies, air movers (e.g., fans and blowers) and/or any other components and/or elements of an information handling system. 
       FIG. 1  illustrates a block diagram of an example system  100  which may represent at least a portion of components present in a data center environment. As shown in  FIG. 1 , system  100  may comprise a plurality of information handling systems  102 , one or more power distribution units  104 , a system manager  106 , and a network  108  communicatively coupled to the information handling systems  102 , power distribution units  104 , and system manager  106 . 
     In some embodiments, each information handling system  102  may comprise a server. As shown in  FIG. 1 , each information handling system  102  may include at least one power supply unit (PSU)  110  configured to receive electrical energy from a corresponding power outlet of power distribution unit  104  in order to provide power to components of information handling system  102 . Although  FIG. 1  depicts each information handling system  102  having two PSUs  110 , an information handling system  102  may include any suitable number of PSUs  110  each of which may be supplied electrical energy from a corresponding outlet of a power distribution unit  104 . 
     Although  FIG. 1  depicts system  100  having two power distribution units  104 , system  100  may include any suitable number of power distribution units  104 . In embodiments including a plurality of power distribution units  104 , some power distribution units  104  may receive a different alternating current source as shown by “AC FEED 1” and “AC FEED 2” in  FIG. 1 . 
     Also as shown in  FIG. 1 , a system manager  106  for monitoring, control, and management of power distribution units  104  and information handling systems  102  may be coupled via network  108  to power distribution units  104  and information handling systems  102  (e.g., via Ethernet). 
     Network  108  may be a network and/or fabric configured to couple system manager  106  to information handling systems  102 , power distribution units  104 , and/or one or more other information handling systems. In these and other embodiments, network  108  may include a communication infrastructure, which provides physical connections, and a management layer, which organizes the physical connections and information handling systems communicatively coupled to network  108 . Network  108  may be implemented as, or may be a part of, a storage area network (SAN), personal area network (PAN), local area network (LAN), a metropolitan area network (MAN), a wide area network (WAN), a wireless local area network (WLAN), a virtual private network (VPN), an intranet, the Internet or any other appropriate architecture or system that facilitates the communication of signals, data and/or messages (generally referred to as data). Network  108  may transmit data via wireless transmissions and/or wire-line transmissions using any storage and/or communication protocol, including without limitation, Fibre Channel, Frame Relay, Asynchronous Transfer Mode (ATM), Internet protocol (IP), other packet-based protocol, small computer system interface (SCSI), Internet SCSI (iSCSI), Serial Attached SCSI (SAS) or any other transport that operates with the SCSI protocol, advanced technology attachment (ATA), serial ATA (SATA), advanced technology attachment packet interface (ATAPI), serial storage architecture (SSA), integrated drive electronics (IDE), and/or any combination thereof. Network  108  and its various components may be implemented using hardware, software, or any combination thereof. 
       FIG. 2  illustrates a block diagram of an example of an information handling system  102 . As depicted, information handling system  102  may include PSU  110 , a motherboard  201 , and one or more other information handling resources. 
     Motherboard  201  may include a circuit board configured to provide structural support for one or more information handling resources of information handling system  102  and/or electrically couple one or more of such information handling resources to each other and/or to other electric or electronic components external to information handling system  102 . As shown in  FIG. 2 , motherboard  201  may include a processor  203 , memory  204 , a management controller  206 , and one or more other information handling resources. 
     Processor  203  may comprise any system, device, or apparatus operable to interpret and/or execute program instructions and/or process data, and may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, processor  203  may interpret and/or execute program instructions and/or process data stored in memory  204  and/or another component of information handling system  102 . Memory  204  may be communicatively coupled to processor  203  and may comprise any system, device, or apparatus operable to retain program instructions or data for a period of time. Memory  204  may comprise random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a PCMCIA card, flash memory, magnetic storage, opto-magnetic storage, or any suitable selection and/or array of volatile or non-volatile memory that retains data after power to information handling system  102  is turned off. 
     Management controller  206  may be configured to provide out-of-band management facilities for management of information handling system  102 . Such management may be made by management controller  206  even if information handling system  102  is powered off or powered to a standby state. Management controller  206  may include a processor, memory, out-of-band network interface  208  separate from and physically isolated from an in-band network interface of information handling system  102 , and/or other embedded information handling resources. In certain embodiments, management controller  206  may include or may be an integral part of a baseboard management controller (BMC) or a remote access controller (e.g., a Dell Remote Access Controller or Integrated Dell Remote Access Controller). In other embodiments, management controller  206  may include or may be an integral part of a chassis management controller (CMC). In some embodiments, management controller  206  may be configured to communicate with PSU  110  to communicate control and/or telemetry data between the two. 
     Network interface  208  may comprise any suitable system, apparatus, or device operable to serve as an interface between management controller  206  and another information handling system (e.g., system manager  106 ) and/or a network (e.g., network  108 ). Network interface  208  may enable management controller  206  to communicate using any suitable transmission protocol and/or standard. In some embodiments, network interface  206  may be configured to communicate with other information handling systems via one or more protocols or standards discussed above with respect to network  108 . In these and other embodiments, network interface  208  may comprise a network interface card, or “NIC.” 
     Generally speaking, PSU  110  may include any system, device, or apparatus configured to supply electrical current to one or more information handling resources of information handling system  102 . As shown in  FIG. 2 , PSU  110  may include one or more microcontroller units (MCUs)  212  and a power train  214 . An MCU  212  may comprise a microprocessor, DSP, ASIC, FPGA, EEPROM, or any combination thereof, or any other device, system, or apparatus for controlling operation of its associated PSU  110 . As such, an MCU  212  may comprise firmware, logic, and/or data for controlling functionality of such PSU  110 . Power train  214  may include any suitable system, device, or apparatus for converting electrical energy received from power distribution unit  104  (e.g., a 120-volt alternating current voltage waveform) into electrical energy usable to information handling resources of information handling system  102  (e.g., 12-volt direct current voltage source). Selected components of an example power train  214  are shown in  FIG. 3  below. 
     In addition to motherboard  201 , processor  203 , memory  204 , management controller  206 , network interface  208 , and PSU  110 , information handling system  102  may include one or more other information handling resources. 
       FIG. 3  illustrates a block diagram of an example power train  214 , in accordance with embodiments of the present disclosure. As shown in  FIG. 3 , power train  214  may include two converter stages: a power factor correction stage  302 , a DC/DC converter stage  304 , a bulk capacitor  306  coupled between an output of power factor correction stage  302  and an input of DC/DC converter stage  304  and an output capacitor  308  coupled to an output of DC/DC converter stage  304 . 
     Rectifier/PFC stage  302  may be configured to, based on an input current i IN , a sinusoidal voltage source v IN , and a bulk capacitor voltage V BULK , shape the input current i IN  to have a sinusoidal waveform in-phase with the source voltage v IN  and to generate regulated DC bus voltage V BULK  on bulk capacitor  306 . 
     DC/DC converter stage  304  may convert bulk capacitor voltage V BULK  to a DC output voltage V OUT  on output capacitor  308  which may be provided to a load (e.g., to information handling resources of information handling system  102  in order to power such information handling resources). In some embodiments, DC/DC converter stage  304  may be implemented as a converter which converts a higher DC voltage (e.g., 400 V) into a lower DC voltage (e.g., 12 V). 
       FIG. 4  illustrates a block diagram of an example power distribution unit  104 , in accordance with embodiments of the present disclosure. As shown in  FIG. 4 , power distribution unit  104  may be an “intelligent” power distribution unit  104  comprising a controller  402 , a plurality of outlets  404 , a plurality of meters  406 , and a network interface  408 . 
     Controller  402  may comprise any system, device, or apparatus operable to monitor and/or control operation of power distribution unit  104 , including control of operation of outlets  404  and the distribution of power thereto, and the reading and/or processing of information from meters  406 . Controller  402  may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, controller  402  may interpret and/or execute program instructions (e.g., firmware) and/or process data stored in computer-readable media accessible to controller  402 . In operation, power distribution unit  104  may distribute electrical energy received from a power source (e.g., a nominally 60 Hz/110 V line voltage in the United States of America or a nominally 50 Hz/220 V line voltage in Europe) to one or more outlets  404 . Each outlet  404  may comprise a suitable electrical connector (e.g., a female electrical connector) for receiving a plug or other male connector of a device (e.g., a PSU  110  of an information handling system  102 ) in order to deliver electrical energy to such device. 
     Each meter  406  may be associated with a corresponding outlet  404  (e.g., in a one-to-one correspondence) and may include any system, device, or apparatus configured to meter one or more parameters (e.g., voltage, current, etc.) indicative of electrical energy delivered from the corresponding outlet  404 . 
     Network interface  408  may comprise any suitable system, apparatus, or device operable to serve as an interface between power distribution unit  104  and an information handling system (e.g., system manager  106 ) and/or a network (e.g., network  108 ). Network interface  408  may enable power distribution unit  104  to communicate using any suitable transmission protocol and/or standard. In some embodiments, power distribution unit  104  may be configured to communicate with other information handling systems (including without limitation system manager  106 ) via one or more protocols or standards discussed above with respect to network  108 . In these and other embodiments, network interface  408  may comprise a NIC. 
       FIG. 5  illustrates a block diagram of an example system manager  106 , in accordance with embodiments of the present disclosure. Also described above, system manager  106  may be configured to monitor, control, and manage power distribution unit  104  and information handling systems  102 . In some embodiments, system manager  106  may comprise a server. In other embodiments, system manager  106  may comprise a personal computer, such as a laptop, notebook, or desktop computer. In yet other embodiments, system manager  106  may be a mobile device sized and shaped to be readily transported and carried on a person of a user of information handling system  102  (e.g., a smart phone, a tablet computing device, a handheld computing device, a personal digital assistant, etc.). As shown in  FIG. 5 , system manager  106  may comprise a processor  503 , a memory  504 , and a network interface  508 . 
     Processor  503  may comprise any system, device, or apparatus operable to interpret and/or execute program instructions and/or process data, and may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, processor  503  may interpret and/or execute program instructions and/or process data stored in memory  504  and/or another component of system manager  106 . Memory  504  may be communicatively coupled to processor  503  and may comprise any system, device, or apparatus operable to retain program instructions or data for a period of time. Memory  504  may comprise random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a PCMCIA card, flash memory, magnetic storage, opto-magnetic storage, or any suitable selection and/or array of volatile or non-volatile memory that retains data after power to system manager  106  is turned off. As shown in  FIG. 5 , memory  504  may have stored thereon a management agent  506 . Management agent  506  may include a program of instructions that may be read and executed by processor  503  in order to carry out the management functionality of system manager  106 , as such functionality is described elsewhere in this disclosure. 
     Network interface  508  may comprise any suitable system, apparatus, or device operable to serve as an interface between system manager  106  and one or more information handling systems (e.g., information handling systems  102 ), other networked devices (e.g., power distribution unit  104 ) and/or a network (e.g., network  108 ). Network interface  508  may enable system manager  106  to communicate using any suitable transmission protocol and/or standard. In some embodiments, system manager  106  may be configured to communicate with other information handling systems via one or more protocols or standards discussed above with respect to network  108 . In these and other embodiments, network interface  508  may comprise a NIC. 
     In operation, system manager  106  may deliver a signal to an information handling system  102 . In response to the signal, the information handling system  102  may cause one of its PSUs  110  to perturb a current drawn by the PSU  110  for a brief period of time. A meter  406  of power distribution unit  104  may detect the perturbation, and the power distribution unit  104  may communicate a signal to the system manager  106  indicative of the current. Based on the perturbation and the response of power distribution unit  104  thereto, system manager  106  may then determine a mapping between the PSU  110  and the outlet  404  to which it is coupled. This process may then be repeated for each PSU  110  of system  100 . 
       FIG. 6  illustrates a flow chart of an example method  600  for mapping PSUs  110  to power distribution units  104  and outlets  404  thereof, in accordance with embodiments of the present disclosure. According to certain embodiments, method  600  may begin at step  602 . As noted above, teachings of the present disclosure may be implemented in a variety of configurations of system  100 . As such, the preferred initialization point for method  600  and the order of the steps comprising method  600  may depend on the implementation chosen. 
     At step  602 , management agent  506  may determine if an update of mapping between PSUs  110  and power distribution units  104  and outlets  404  thereof is needed. An update may be needed for many reasons, including without limitation, a policy to periodically (e.g., monthly) update mapping, a user request to perform an update, and/or other suitable reasons. For example, a user may desire to request an update in response to making a change to the power topology of system  100  (e.g., replacement of PSU  110 , replacement of power cord, relocation of an information handling system  102 , etc.). If an update is needed, method  600  may proceed to step  604 , and management agent may authorize a process to map all information handling systems  102  of system  100  to their corresponding power distribution units  104  and outlets  404 , and management agent  506  may store a map indicative of the power topology. Otherwise, method  600  may end. 
     At step  604 , management agent  506  may communicate (e.g., via network  108 ) a message to an information handling system  102 . In some embodiments, such message may comprise one or more datagrams (e.g., packets) communicated via Ethernet. 
     At step  606 , management controller  206  of an information handling system  102  may receive the message from system manager  106  and, in response, may communicate a message to an MCU  212  of an unmapped PSU  110 , wherein the message requests that the PSU  110  cause a current perturbation. At step  608 , in response to the message from management controller  206 , MCU  212  of the PSU  110  may cause a current perturbation for a period of time. Examples of such current perturbations are described in greater detail below in references to  FIGS. 7-9 . 
     At step  610 , a meter  406  metering an outlet  404  to which the PSU  110  is electrically coupled may, in the course of its normal metering of such outlet  404 , detect such perturbation of the current of the PSU  110 . At step  612 , as part of its normal communication of meter data to system manager  106  or in response to a request from system manager  106  to communicate such meter data, controller  402  may communicate a message to system manager  106  which may include information regarding which outlet  404  experienced its own perturbation in response to the perturbation at the PSU  110 . 
     At step  614 , system manager  106  may receive the meter data from power distribution unit  104  and determine from such data which outlet  404  experienced its own perturbation in response to the perturbation at the PSU  110 . Based on such determination, system manager  106  may, in its configuration data, record (e.g., in memory  504  or another computer-readable medium accessible to processor  503 ) that the PSU  110  is electrically coupled to such outlet  404 . 
     At step  616 , management agent  506  may determine if all PSUs  110  of information handling systems  102  of system  100  have each been mapped to an associated outlet  404  of a power distribution unit  104  to which each PSU  110  is electrically coupled. If all PSUs  110  have been so mapped, method  600  may end. Otherwise, method  600  may proceed again to step  604 , and steps  604  through  614  may repeat for each PSU  110  of system  100 . 
     Although  FIG. 6  discloses a particular number of steps to be taken with respect to method  600 , method  600  may be executed with greater or fewer steps than those depicted in  FIG. 6 . In addition, although  FIG. 6  discloses a certain order of steps to be taken with respect to method  600 , the steps comprising method  600  may be completed in any suitable order. 
     Method  600  may be implemented using system  100 , components thereof or any other system operable to implement method  600 . In certain embodiments, method  600  may be implemented partially or fully in software and/or firmware embodied in computer-readable media. 
       FIG. 7  illustrates a graph depicting an example current perturbation that may be applied to a PSU  110  in order to facilitate mapping of the PSU  110  to an outlet  404  of a power distribution unit  104 , in accordance with embodiments of the present disclosure. Such perturbation may be applied, for example, at step  608  of method  600 . In the embodiments represented by  FIG. 7 , PSU  110  may, in response to a message received at its MCU  212  to perturb its current, disable power factor correction stage  302  of its power train  214  for a short period of time (e.g., one half-line cycle). In some of such embodiments, the disabling of power factor correction stage  302  may be less than a hold-up time of the PSU  110 , such that power factor correction stage  302  may be disabled without affecting the voltage V OUT  output by power train  214 . During such disabling of power factor correction stage  302 , the input current i IN  to power factor correction stage  302  may be forced to zero, as shown in  FIG. 7 . This brief zeroing of current may be detected by a meter  406 , with such detection communicated to system manager  106  as described above, allowing system manager  106  to determine that the PSU  110  having the disturbance is electrically coupled to a specific outlet  404  of power distribution unit  104 . 
       FIG. 8  illustrates a graph depicting an example current perturbation that may be applied to a PSU  110  in order to facilitate mapping of the PSU  110  to an outlet  404  of a power distribution unit  104 , in accordance with embodiments of the present disclosure. Such perturbation may be applied, for example, at step  608  of method  600 . In the embodiments represented by  FIG. 8 , PSU  110  may, in response to a message received at its MCU  212  to perturb its current, inject harmonics into input current i IN . For example,  FIG. 8  depicts 11 th -order harmonics being injected into input current i IN . Power factor correction stage  302  may respond to the injected current by increasing the total harmonic distortion of input current i IN . Such hike in total harmonic distortion may be detected by a meter  406 , with such detection communicated to system manager  106  as described above, allowing system manager  106  to determine that the PSU  110  having the disturbance is electrically coupled to a specific outlet  404  of power distribution unit  104 . 
       FIG. 9  illustrates a graph depicting an example current perturbation that may be applied to a PSU  110  in order to facilitate mapping of the PSU  110  to an outlet  404  of a power distribution unit  104 , in accordance with embodiments of the present disclosure. Such perturbation may be applied, for example, at step  608  of method  600 . In the embodiments represented by  FIG. 9 , PSU  110  may, in response to a message received at its MCU  212  to perturb its current, introduce a phase delay to input current i IN . In response to input current i IN  and source voltage v IN  becoming out of phase, the power factor of the PSU  110  may decrease for a period of time, until the phase delay is corrected by power factor correction stage  302 . Such decrease in power factor may be detected by a meter  406 , with such detection communicated to system manager  106  as described above, allowing system manager  106  to determine that the PSU  110  having the disturbance is electrically coupled to a specific outlet  404  of power distribution unit  104 . 
     As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electronic communication or mechanical communication, as applicable, whether connected indirectly or directly, with or without intervening elements. 
     This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. 
     All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the disclosure and the concepts contributed by the inventor to furthering the art, and are construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure.