Patent Description:
Typically, a PDU has a fixed capacity of electrical power that is equal to the electrical capacity of other PDUs within a data center. This enables for maximal utilization of power capacity of the data center. A lack of load balancing across PDUs within a data center may lead to unused or stranded power and underutilization of electrical infrastructure. Stranded power is the electricity that is wasted or unable to be used. When measured across an entire data center, this stranded power may amount to a staggering waste of power resources and expensive infrastructure. Additionally, if a data center runs out of power capacity, then a cloud service provider is required to build or rent another data center to provide its services.

Due to variability in power needs of workloads (i.e., applications and other software running on the servers in a data center), it can be difficult to assign workloads in a data center for maximal utilization of power capacity of a data center. This is further exacerbated by the deployment of workloads to servers at a row level rather than at a rack level. As a result, PDUs may become underutilized and power provided by PDUs stranded. <CIT> describes a busway system that enables multiple interchangeable power support redundancies to be provided to electrical loads. The busway system includes multiple busways extending through an aisle space, where some busways carry power from separate primary power sources, and one or more busways carry power from a secondary power source. Busways are coupled to loads to provide power support directly to the loads, indirectly via devices that distribute power to the loads via branch circuits, etc. The power support redundancy provided to a load is established based at least in part upon which busways are coupled to the load, and power support redundancies can be changed by changing the couplings of particular busways with the loads. The busways can extend through the aisle space in a staggered configuration to enable load balancing between busways by restricting loads in certain regions of the aisle space to coupling with certain busways and not others.

It is the object of the present invention to provide an improved method and system for power distribution in a data center.

Methods, systems, and apparatuses are described herein that enable the recovery of stranded power in a data center. For example, a power distribution system for recovering stranded power in a data center includes a first power distribution unit (PDU), a first busway segment that is operable to electrically connect the first PDU to a first set of server racks in a first row of server racks, a second busway segment that is operable to electrically connect the first PDU to a second set of server racks in a second row of server racks, a second PDU, a third busway segment that is operable to electrically connect the second PDU to a third set of server racks in a third row of server racks, and a fourth busway segment that is operable to electrically connect the second PDU to a fourth set of server racks in the second row of server racks.

Additionally, the power distribution system may further include a third PDU, a fifth busway segment that is operable to electrically connect the third PDU to a fifth set of server racks in a fourth row of server racks, and a sixth busway segment that is operable to electrically connect the third PDU to a sixth set of server racks in the second row of server racks.

The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the application and, together with the description, further serve to explain the principles of the embodiments and to enable a person skilled in the relevant art(s) to make and use the embodiments.

References in the specification to "one embodiment," "an embodiment," "an example embodiment," or the like, indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of persons skilled in the relevant art(s) to implement such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

In the discussion, unless otherwise stated, adjectives such as "substantially," "approximately," and "about" modifying a condition or relationship characteristic of a feature or features of an embodiment of the disclosure, are understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which it is intended.

Data centers, such as those used to support cloud computing, demand massive amounts of uninterrupted power to operate successfully and seamlessly. The distribution and management of power in a data center may be accomplished through the use of power distribution units (PDUs) and busways. A PDU is a component in an electrical infrastructure designed to distribute power from upstream electrical path(s) (e.g., a primary power source of a building) to downstream loads (e.g., equipment racks in a data center). Busways generally serve as an agile solution (as opposed to cable or conduit) to channel power from PDUs to one or more rows of server racks in a data center.

Due to variability in power needs of workloads (i.e., applications and other software running on the servers in a data center), it can be difficult to assign workloads in a data center for maximal utilization of power capacity of a data center. This is further exacerbated by the deployment of workloads to servers at a row level rather than at a rack level. As a result, PDUs may become underutilized and power provided by PDUs stranded.

To help illustrate the foregoing, <FIG> is described. <FIG> shows a block diagram of an example power distribution system <NUM> for a data center, according to the prior art. As shown in <FIG>, a data center <NUM> includes cells <NUM>, <NUM>, <NUM>, and <NUM>. Each cell is a discrete power distribution system within the data center and is provided power by a primary power source and secondary power sources. A primary power source and secondary power sources may be power generated by a public utility or a private generation facility. For example, as shown in <FIG>, cell <NUM> is provided power from a primary power source A, cell <NUM> is provided power from a primary power source B, cell <NUM> is provided power from a primary power source C, and cell <NUM> is provided power from a primary power source D. Each primary power source also serves as a secondary power source for cells that it is not servicing as a primary power source.

As further shown in <FIG>, cell <NUM> includes static switches <NUM>, <NUM>, and <NUM>. Static switches may be configured to switch between a primary power source and a secondary power source in case of an interruption of electrical service of the primary power source, allowing for transferring of electric loads between two independent power sources without interruption. For example, static switch <NUM> is connected to primary power source A and secondary power source B. Static switch <NUM> is connected to primary power source A and secondary power source C. Static switch <NUM> is connected to primary power source A and secondary power source D.

Cell <NUM> also includes power distribution units ("PDU") <NUM>, <NUM>, and <NUM>. PDUs are devices including multiple outputs that are designed to distribute electric power, for example, to racks of servers and networking equipment located within a data center. Although connections are not shown in <FIG>, PDU <NUM> is connected to static switch <NUM>, PDU <NUM> is connected to static switch <NUM>, and PDU <NUM> is connected to static switch <NUM>.

PDU <NUM> is configured to provide power from a power source to which it is connected via static switch <NUM> to one or more rows of server racks. PDU <NUM> provides such power to the one or more rows of server racks via busways. For example, as shown in <FIG>, PDU <NUM> may distribute power from primary power source A via an overhead or underfloor busway system (represented in <FIG> as solid lines from PDU <NUM> through rows of server racks <NUM>, <NUM>, and <NUM>) that is operable to electrically connect PDU <NUM> to rows of server racks <NUM>, <NUM>, and <NUM>. In the case that primary power source A fails to deliver power, PDU <NUM> may distribute power from secondary power source B via the same busway system that is operable to electrically connect PDU <NUM> to rows of server racks <NUM>, <NUM>, and <NUM>.

PDU <NUM> is similarly configured to provide power from a power source to which it is connected via static switch <NUM> to one or more rows of server racks. PDU <NUM> provides such power to the one or more rows of server racks via busways. For example, as shown in <FIG>, PDU <NUM> may distribute power from primary power source A via an overhead or an underfloor busway system (represented in <FIG> as solid lines from PDU <NUM> through rows of server racks <NUM>, <NUM>, and <NUM>) that is operable to electrically connect PDU <NUM> to rows of server racks <NUM>, <NUM>, and <NUM>. In the case primary power source A fails to deliver power, PDU <NUM> may distribute power from secondary power source C via the busway system that is operable to electrically connect PDU <NUM> to rows of server racks <NUM>, <NUM>, and <NUM>.

In addition, PDU <NUM> is similarly configured to provide from a power source to which it is connected via static switch <NUM> to one or more rows of server racks. PDU <NUM> provides such power to the one or more rows of server racks via busways. For example, as shown in <FIG>, PDU <NUM> may distribute power from primary power source A via an overhead or an underfloor busway system (represented in <FIG> as solid lines from PDU <NUM> through rows of server racks <NUM>, <NUM>, and <NUM>) that is operable to electrically connect PDU <NUM> to rows of server racks <NUM>, <NUM>, and <NUM>. In the case primary power source A fails to deliver power, PDU <NUM> may distribute power from secondary power source D via the busway system that is operable to electrically connect PDU <NUM> to rows of server racks <NUM>, <NUM>, and <NUM>.

As further shown in <FIG>, row of server racks <NUM> and row of server racks <NUM> line up along a hot aisle containment ("HAC") <NUM>, row of server racks <NUM> and row of server racks <NUM> line up along a HAC <NUM>, row of server racks <NUM> and row of server racks <NUM> line up along a HAC <NUM>, row of server racks <NUM> and row of server racks <NUM> line up along a HAC <NUM>, and row of server racks <NUM> line up along a HAC <NUM>. A HAC is an enclosure that collects hot exhaust air from server rack devices and directs the hot exhaust air out of the data center. Rows of server racks <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may include several rack positions, and each rack position may include servers and other types of equipment (e.g., network routers or switches, cooling fans, etc.).

As shown in <FIG>, cells <NUM>, <NUM>, and <NUM> have similar power distribution configurations as cell <NUM>. For example, cells <NUM>, <NUM>, and <NUM> each include three switches configured to provide power from a primary power source or a secondary power source and to connect to a corresponding PDU of three PDUs in a cell. In addition, each PDU of the three PDUs included in cells <NUM>, <NUM>, and <NUM> provide power via a busway system that is operable to electrically connect a PDU to three rows of server racks.

Based upon this power distribution configuration, in order to utilize the full capacity of the power distribution system <NUM>, the load across the PDUs and static switches in a cell need to be balanced. In addition, the load across PDUs cannot exceed the maximum power assigned to each PDU and each cell within the data center.

Furthermore, due to variability in power needs of workloads, it can be difficult to assign workloads in a data center for maximal utilization of power capacity of a data center. This is further exacerbated by the deployment of workloads to servers at a row level rather than at a rack level. The larger the power needs of workloads assigned to a data center, the less flexibility exists in assigning workloads in a data center (e.g., assignment of power in smaller units such as at a rack level allows for more precise, incremental utilization of the supply of power in order to reach maximum capacity of power). Any inefficiency in power distribution results in PDUs becoming underutilized and power becoming stranded.

For example, let it be determined that data center <NUM> in <FIG> carries a <NUM>,<NUM> kW maximum capacity. Based on this determination, each of data center <NUM>'s four cells (<NUM>, <NUM>, <NUM>, and <NUM>) carry a maximum power capacity of <NUM> kW. Drilling down more granularly, it can be surmised that each of the three PDUs per cell carry a maximum power capacity of <NUM> kW (based on the principle of load balancing across all PDUs). Also, as shown in <FIG>, each PDU services three dedicated rows of server racks (i.e., rows <NUM>, <NUM>, and <NUM> to PDU <NUM>, rows <NUM>, <NUM>, and <NUM> to PDU <NUM>, and rows <NUM>, <NUM>, and <NUM> to PDU <NUM>).

Now, in an example scenario A, consider that the rows of server racks are assigned workloads with a power need of <NUM> kW and each load on a PDU cannot exceed <NUM> kW of power. As a result, the maximum wattage that is provided per PDU is the equivalent of two rows, or <NUM> kW (as workloads are assigned at a row level). Thus, each PDU faces up to <NUM> kW of unusable power. Across an entire cell, <NUM> kW of power will remain untapped. This signifies a <NUM>% underutilization of power (as <NUM> kW is <NUM>% of the <NUM> kW maximum power capacity of the cells of data center <NUM>).

To further illustrate, in an example scenario B, workloads with varying power needs are assigned to rows of server racks in data center <NUM>. For instance, consider that each PDU in cell <NUM> is servicing a first row that is assigned a workload with a power need of <NUM> kW, a second row that is assigned a workload with a power need of <NUM> kW, and a third row that is assigned a workload with a power need of <NUM> kW. As a result, the wattage that is provided per PDU is <NUM> kW. As such, each PDU faces up to <NUM> kW of unusable power, and across an entire cell, <NUM> kW of power will remain untapped. This results in a <NUM>% underutilization of power (as <NUM> kW is <NUM>% of the <NUM> kW maximum power capacity of the cells of data center <NUM>).

One solution to combat stranded power is to map a workload to the PDUs that are underutilized within each cell. This helps balance loads across the PDUs for optimal operability and efficiently accommodates the varying levels of workload power requirements experienced across the server rack rows. This solution can be achieved via a segmented busway system in a "recovery row" of server racks that allows multiple PDUs to provide power to the same row of server rack rows. This emerges as a delineation from current power distribution systems, as convention dictates that a single PDU services a fixed row or set of rows, rather than multiple PDUs servicing the same row of server racks.

<FIG> more clearly demonstrates how a segmented busway system functions. Specifically, <FIG> shows a block diagram of an example power distribution system <NUM> with a segmented busway system for a data center <NUM>, according to an example embodiment. Data center <NUM> is similar to data center <NUM> featured in <FIG> in that it includes four cells-namely, cells <NUM>, <NUM>, <NUM>, and <NUM>. Furthermore, as shown in <FIG>, cell <NUM> is provided power from a primary power source A, cell <NUM> is provided power from a primary power source B, cell <NUM> is provided power from a primary power source C, and cell <NUM> is provided power from a primary power source D. In <FIG>, static switches function in the same fashion as described above with respect to <FIG>, with static switches <NUM>, <NUM>, and <NUM> servicing cell <NUM>, for example. Each primary power source also serves as a secondary power source for cells that it is not servicing as a primary power source. For example, static switch <NUM> is connected to primary power source A and secondary power source B. Static switch <NUM> is connected to primary power source A and secondary power source C. Static switch <NUM> is connected to primary power source A and secondary power source D. This same pattern is showcased within cell <NUM>, <NUM>, and <NUM>.

Each cell noted in <FIG> includes three PDUs. Each PDU operates to distribute power from a power source to which it is connected via a static switch to various server racks. As an abbreviated example, cell <NUM> includes PDUs <NUM>, <NUM>, and <NUM>. Although connections are not shown in <FIG>, PDU <NUM> is connected to static switch <NUM>, PDU <NUM> is connected to static switch <NUM>, and PDU <NUM> is connected to static switch <NUM>. Moreover, the HACs noted in <FIG> are placed and operate in the same manner as those discussed above with respect to <FIG>. Cell <NUM>, for example, will show that HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, and HAC <NUM> services row <NUM>.

In regards to racks of server rows, cell <NUM> will again garner a closer look. PDU <NUM> is configured to provide power via a busway system to the entire row of rows <NUM> and <NUM>, a portion of row <NUM>, and a portion of row <NUM> (although connections are not shown in <FIG>). In <FIG>, the "portions" are represented by two thirds of row <NUM> and one third of row <NUM>, totaling <NUM> rows of server racks connected to PDU <NUM> when including rows of <NUM> and <NUM>. In other embodiments, the rows of server racks may be apportioned differently (e.g., half of a row, quarter of a row, etc.). In line with this example, PDU <NUM> is configured to provide power via a busway system to the remaining portion of row <NUM>, full rows <NUM> and <NUM>, a portion of row <NUM>, and a portion of <NUM> (although connections are not shown in <FIG>). In <FIG>, the "portions" are represented by one third of row <NUM>, one third of row <NUM>, and one third of row <NUM>, totaling <NUM> rows total across PDU <NUM> when including full rows <NUM> and <NUM>. Lastly, PDU <NUM> is configured to provide power via a busway system to the remaining portion of row <NUM>, full rows <NUM> and <NUM>, and a portion of row <NUM>. In <FIG>, the "portions" are represented by two thirds of row <NUM> and one third of row <NUM>, totaling <NUM> rows total across PDU <NUM> when including full rows <NUM> and <NUM>. This behavior follows suit across all PDUs and their corresponding rows of the cells within data center <NUM> (i.e., cells <NUM>, <NUM>, and <NUM>).

In application, this segmented busway system yields drastically less percentages of stranded power across a data center (noted at <NUM>% in the example regarding <FIG>). For instance, let it be assumed in the segmented busway system drawn out in <FIG> that cell <NUM> has a wattage of <NUM> kW, with <NUM> PDUs (<NUM>, <NUM>, and <NUM>). These PDUs carry a maximum power of <NUM> kW each and service rows with workloads with <NUM> kW power needs. In this example, however, each PDU distributes power in the manner expressed throughout <FIG>. (e.g., PDU <NUM> services all of rows <NUM> and <NUM>, two thirds of <NUM>, and one third of <NUM>). Row <NUM> emerges as a critical improvement to the data center, as it can connect to all of the three PDUs in cell <NUM> to receive power.

Specifically, referencing scenario A explained above, this row can be assigned stranded power from PDUs <NUM>, <NUM>, and <NUM>, even in tandem, to service a <NUM> kW workload power requirement. For example, if row <NUM> receives an equal amount of power from PDUs <NUM>, <NUM>, and <NUM> at <NUM> kW each to satisfy the workload requirement, then the previous stranded power wattage reduces from <NUM> kW to <NUM> kW per PDU. Across cell <NUM>, total stranded power shrinks from <NUM> kW to <NUM> kW, or <NUM>% stranded power (down from <NUM>% in <FIG>).

Similarly, referencing scenario B explained above, row <NUM> can utilize equal amounts of stranded power from PDUs <NUM>, <NUM>, and <NUM> to service a <NUM> kW workload power requirement. For example, if row <NUM> receives an equal amount of power from PDUs <NUM>, <NUM>, and <NUM> at <NUM> kW each to satisfy the workload requirement, then the previous stranded power wattage reduces from <NUM> kW to <NUM> kW per PDU. Across cell <NUM>, total stranded power shrinks from <NUM> kW to <NUM> kW, or <NUM>% stranded power (down from <NUM>% in <FIG>). Based on harnessing power from multiple PDUs, rows are able to tap power otherwise wasted. This segmented busway system provides a clean, immediate, and scalable solution to reduce the amount of stranded power.

Instead of a segmented busway, like with row <NUM>, a busway system can be used to provide more flexibility in recovering stranded power from each PDU in a recovery row, no longer limiting PDUs to route their respective power to a predetermined portion of a row of server racks.

For example, <FIG> provides an example of a detailed layout of a busway system described above. Specifically, <FIG> shows a block diagram of an example power distribution system <NUM> including a flexible busway system for a data center <NUM>, according to an example embodiment. Data center <NUM> is similar to data centers <NUM> and <NUM> featured in <FIG> and <FIG> in that it includes four cells-namely, cells <NUM>, <NUM>, <NUM>, and <NUM>. Furthermore, as shown in <FIG>, cell <NUM> is provided power from a primary power source A, cell <NUM> is provided power from a primary power source B, cell <NUM> is provided power from a primary power source C, and cell <NUM> is provided power from a primary power source D. In <FIG>, static switches function in the same fashion as described above with respect to <FIG> and <FIG>, with static switches <NUM>, <NUM>, and <NUM> servicing cell <NUM>, for example. Each primary power source also serves as a secondary power source for cells that it is not servicing as a primary power source. For example, static switch <NUM> is connected to primary power source A and secondary power source B. Static switch <NUM> is connected to primary power source A and secondary power source C. Static switch <NUM> is connected to primary power source A and secondary power source D. This same pattern is showcased within cell <NUM>, <NUM>, and <NUM>.

Each cell noted in <FIG> includes three PDUs. Each PDU operates to distribute power from a power source to which it is connected via a static switch to various server racks. As an abbreviated example, cell <NUM> includes PDUs <NUM>, <NUM>, and <NUM>. Although connections are not shown in <FIG>, PDU <NUM> is connected to static switch <NUM>, PDU <NUM> is connected to static switch <NUM>, and PDU <NUM> is connected to static switch <NUM>. Moreover, the HACs noted in <FIG> are placed and operate in a similar manner as those discussed above with respect to <FIG> and <FIG>. Cell <NUM>, for example, will show that HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, and HAC <NUM> services rows <NUM> and <NUM>.

In regards to rows of server racks, in cell <NUM>, PDU <NUM> is configured to provide power via a busway system to the entire rows of server racks <NUM>, <NUM>, and <NUM>, and any amount of row <NUM> (i.e., from one server rack of row <NUM> to all server racks of row <NUM>). In addition, PDU <NUM> is configured to provide power to the entire rows of server racks <NUM>, <NUM>, and <NUM>, and any amount of row <NUM> (i.e., from one server rack of row <NUM> to all server racks of row <NUM>). Lastly, PDU <NUM> is configured to provide power to the entire rows of server racks <NUM>, <NUM> and <NUM> and any amount of row <NUM> (i.e., from one server rack of row <NUM> to all server racks of row <NUM>). This behavior follows suit across all PDUs and their corresponding rows of the cells within data center <NUM> (i.e., cells <NUM>, <NUM>, and <NUM>).

In application, using the example described above with reference to <FIG> and <FIG>, it can be assumed that each cell in data center <NUM> has a wattage of <NUM> kW, with <NUM> PDUs. In cell <NUM>, the corresponding PDUs would include PDU <NUM>, <NUM>, and <NUM>. These PDUs carry a maximum power of <NUM> kW each and service rows with workloads requiring <NUM> kW per row. In this example, however, each PDU distributes power in the manner expressed throughout <FIG>, in which a single PDU can provide complete power to a row if possible, or just a fraction of the power to the row (e.g., PDU <NUM> services all of rows <NUM>, <NUM> and <NUM>, and any amount of power to <NUM> as to achieve load balancing).

In this embodiment, referencing scenario example A explained above, row <NUM> can be assigned any combination of stranded power from the three PDUs, even in tandem, to provide power for a <NUM> kW workload power requirement. To illustrate, assume row <NUM> receives <NUM> kW of stranded power from PDU <NUM>, <NUM> kW from PDU <NUM>, and <NUM> kW from PDU <NUM>. This means the previous stranded power wattage reduces from <NUM> kW to zero kW for PDU <NUM> and down from <NUM> kW to <NUM> kW for PDUs <NUM> and <NUM>. Across cell <NUM>, total stranded power amounts to <NUM> kW, or <NUM>% stranded power (down from <NUM>% in <FIG>).

The ability to recover a variable amount of power from each PDU not only enables the recovery of stranded power, but also provides a more efficient and flexible manner in balancing loads across PDUs. To illustrate, in an example scenario C, consider that PDUs <NUM> and <NUM> are servicing a first row that is assigned a workload with a power need of <NUM> kW, a second row that is assigned a workload with a power need of <NUM> kW, and a third row that is assigned a workload with a power need of <NUM> kW, thereby resulting in PDUs <NUM> and <NUM> facing up to <NUM> kW of unused power. Consider further that PDU <NUM> is servicing a first row that is assigned a workload with a power need of <NUM> kW and a second row that is assigned a workload with a power need of <NUM> kW, thereby resulting in PDU <NUM> facing up to <NUM> kW of unused power.

If, in this scenario, a workload with a power need of <NUM> kW is assigned to cell <NUM>, it could not be assigned to a third row serviced by PDU <NUM> as it would exceed the maximum power capacity of <NUM> kW of PDU <NUM>. However, row <NUM> could be assigned a combination of stranded power from each PDU, such as <NUM> kW from PDUs <NUM> and <NUM> and <NUM> kW from PDU <NUM>, to satisfy the <NUM> kW workload power requirement and balance the load across PDUs <NUM>, <NUM>, and <NUM>, as each PDU is providing a <NUM> kW of power. In this scenario, across cell <NUM>, total stranded power amounts to <NUM> kW, or <NUM>% stranded power (down from <NUM>% in <FIG>).

The physical placement of a recovery row in a data center can also impact power distribution efficiency. To illustrate, by placing the recovery row in the center of a data center, expenditures like equipment, floorspace, and infrastructure are spared. For example, less wiring would be required to connect a busway system in a recovery row to its corresponding PDUs in a data center shown in <FIG>. In particular, <FIG> is a block diagram of an example power distribution system <NUM> including a flexible busway system in the center of a cell of a data center, according to an example embodiment.

In this embodiment, data center <NUM> includes cells <NUM>, <NUM>, <NUM>, and <NUM>. In addition, cell <NUM> is provided power from a primary power source A, cell <NUM> is provided power from a primary power source B, cell <NUM> is provided power from a primary power source C, and cell <NUM> is provided power from a primary power source D. In <FIG>, static switches function in the a similar fashion to that described above in reference to <FIG>, <FIG>, and <FIG>. Each primary power source also serves as a secondary power source for cells that it is not servicing as a primary power source. For example, static switch <NUM> is connected to primary power source A and secondary power source B. Static switch <NUM> is connected to primary power source A and secondary power source C. Static switch <NUM> is connected to primary power source A and secondary power source D. This same pattern is showcased within cell <NUM>, <NUM>, and <NUM>.

Each cell noted in <FIG> includes three PDUs. Each PDU operates to distribute power from a power source to which it is connected via a static switch to various server racks. To demonstrate, cell <NUM> includes PDUs <NUM>, <NUM>, and <NUM>. Although connections are not shown in <FIG>, PDU <NUM> is connected to static switch <NUM>, PDU <NUM> is connected to static switch <NUM>, and PDU <NUM> is connected to static switch <NUM>. Moreover, the HACs noted in <FIG> are placed and operate in a similar manner as those discussed above with respect to <FIG>, <FIG>, and <FIG>. HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, HAC <NUM> services rows <NUM> and <NUM>, and HAC <NUM> services row <NUM> and <NUM>.

In regards to rows of server racks, in cell <NUM> of <FIG>, PDU <NUM> is configured to provide power to the entire rows of server racks <NUM>, <NUM>, and <NUM>, and any amount to center row <NUM> (i.e., from one server rack of row <NUM> to all server racks of row <NUM>). PDU <NUM> is configured to provide power to the entire rows of server racks <NUM>, <NUM>, and <NUM>, and any amount to center row <NUM> (i.e., from one server rack of row <NUM> to all server racks of row <NUM>). Lastly, PDU <NUM> is configured to provide power to the entire rows of server racks <NUM>, <NUM>, and <NUM>, and any amount to <NUM> (i.e., from one server rack of row <NUM> to all server racks of row <NUM>). This behavior can be observed within the remaining three cells of data center <NUM> (i.e., cells <NUM>, <NUM>, and <NUM>).

By placing the recovery row in the center of the data center, less infrastructure is needed to connect busway systems in row <NUM> to their corresponding PDUs. For example, in referencing <FIG> and <FIG>, less infrastructure (e.g., conduit, tray, wire) is required to connect PDU <NUM> to its corresponding busway system in recovery row <NUM> of <FIG> in comparison to connecting PDU row <NUM> to its corresponding busway system in recovery row <NUM> of <FIG>. Nonetheless, in other embodiments, a recovery row may be placed in any row in a data center depending upon the layout or power distribution infrastructure of a data center.

Systems <NUM>, <NUM>, and <NUM> may operate in various ways to enable the recovery of stranded power in a data center. For instance, in embodiments, systems <NUM>, <NUM>, and <NUM> may operate according to <FIG> depicts a flowchart <NUM> of a method for recovering power from a first and second underutilized PDU, according to an example embodiment. Even though each of systems <NUM>, <NUM>, and <NUM> of <FIG> can operate according to <FIG> will be described in further detail with continued reference to <FIG>. However, other structural and operational embodiments will be apparent to persons skilled in the relevant art(s) based on the following discussion regarding flowchart <NUM>.

As shown in <FIG>, the method of flowchart <NUM> begins at step <NUM>. In step <NUM>, power from a first PDU is provided via a first busway segment to a first set of server racks in a first row of server racks. For example, and with continued reference to <FIG>, power is provided from PDU <NUM> via a first busway segment (represented in <FIG> as a solid line from PDU <NUM> through row of server racks <NUM>) to a first set of server racks in row of server racks <NUM>.

At step <NUM>, power from the first PDU is provided via a second busway segment to a second set of server racks in a second row of server racks. For example, and with continued reference to <FIG>, although connections are not show in <FIG>, power from PDU <NUM> is provided via a second busway segment (represented in <FIG> as a solid line through row of server racks <NUM>) to a second set of server racks in row of server racks <NUM>.

At step <NUM>, power is provided from a second PDU via a third busway segment to a third set of server racks in a third row of server racks. For example, and with continued reference to <FIG>, power from PDU <NUM> is provided via a third busway segment (represented in <FIG> as a solid line from PDU <NUM> through row of server racks <NUM>) to a third set of server racks in row of server racks <NUM>.

At step <NUM>, power is provided from the second PDU via a fourth busway segment to a fourth set of server racks in the second row of server racks. For example, and with continued reference to <FIG>, although connections are not show in <FIG>, power from PDU <NUM> is provided via a fourth busway segment (represented in <FIG> as a solid line through row of server racks <NUM>) to a fourth set of server racks in row of server racks <NUM>.

In embodiments, the second set of server racks in row of server racks <NUM> and the fourth set of server racks in row of server racks <NUM> may be non-overlapping (e.g., the second set may comprise a first half of server racks of row <NUM> while the fourth set may comprise a second half of server racks of row <NUM> and vice versa). In addition, in embodiments, the first set of server racks may be larger than the second set of server racks (e.g., assuming rows include the same number of racks, the first set may include all the server racks in row <NUM>, while the second set of server racks may include a first half of server racks of row <NUM>) and the third set of server racks may be larger than the fourth set of server racks (e.g., assuming rows include the same number of racks, the third set may include all the server racks in row <NUM>, while the second set of server racks may include a second half of server racks of row <NUM>).

Still yet, in embodiments, assuming the number of server racks in each row of server racks is the same, the first set of server racks may comprise all of the server racks in the first row of server racks (e.g., all the server racks in row <NUM>), the second set of server racks may comprise a first portion of the server racks in the second row of server racks (e.g., a first portion of server racks in row <NUM>), the third set of server racks may comprise all of the server racks in the third row of server racks (e.g., all the server racks in row <NUM>), and the fourth set of server racks may comprise a second portion of the server racks in the second row of server racks (e.g., a second portion of server racks in row <NUM>). Furthermore, the first portion of the server racks in row <NUM> of server racks may be the same as the number of server racks in the second portion of the server racks in row <NUM> of server racks.

For instance, in embodiments, systems <NUM>, <NUM>, and <NUM> may operate according to <FIG> depicts a flowchart <NUM> of a method for recovering power from a third underutilized PDU, according to an example embodiment. Even though each of systems <NUM>, <NUM>, and <NUM> can operate according to <FIG> will be described in further detail with continued reference to <FIG>. However, other structural and operational embodiments will be apparent to persons skilled in the relevant art(s) based on the following discussion regarding flowchart <NUM>.

As shown in <FIG>, the method of flowchart <NUM> begins at step <NUM>. In step <NUM>, power is provided from a third PDU via a fifth busway segment to a fifth set of server racks in a fourth row of server racks. For example, and with continued reference to <FIG>, power is provided from PDU <NUM> via a busway segment (represented in <FIG> as a solid line from PDU <NUM> through row of server racks <NUM>) to a fifth set of server racks in row of server racks <NUM>.

At step <NUM>, power is provided from the third PDU via a sixth busway segment to a sixth set of server racks in the second row of server racks. For example, and with continued reference to <FIG>, although connections are not show in <FIG>, power is provided from PDU <NUM> via a sixth busway segment (represented in <FIG> as a solid line through row of server racks <NUM>) to a sixth set of server racks in the second row of server racks <NUM>. In embodiments, the second set of server racks described in <FIG>, the fourth set of server racks described in <FIG>, and the sixth set of server racks described in <FIG> in row of server racks <NUM> are non-overlapping. In addition, in some embodiments, PDUs <NUM>, <NUM>, and <NUM> may be configured to provide power to the second set of server racks described in <FIG>, the fourth set of server racks described in <FIG>, and the sixth set of server racks described in <FIG> in row of server racks <NUM>, in which the sets are overlapping. Moreover, PDUs <NUM>, <NUM>, and <NUM> may be configured to provide power to the second set of server racks described in <FIG>, the fourth set of server racks described in <FIG>, and the sixth set of server racks described in <FIG> in row of server racks <NUM>, in which each set comprises all the server racks in the second row of server racks.

Claim 1:
A power distribution system for a data center (<NUM>, <NUM>, <NUM>), comprising:
a first power distribution unit, PDU (<NUM>, <NUM>, <NUM>);
a first busway segment that is operable to electrically connect the first PDU to a first set of server racks in a first row (<NUM>, <NUM>, <NUM>) of server racks in a first hot aisle containment, HAC (<NUM>, <NUM>, <NUM>);
a second busway segment that is operable to electrically connect the first PDU to a second set of server racks in a second row (<NUM>, <NUM>, <NUM>) of server racks in a second HAC (<NUM>, <NUM>, <NUM>);
a second PDU (<NUM>, <NUM>, <NUM>);
a third busway segment that is operable to electrically connect the second PDU to a third set of server racks in a third row (<NUM>, <NUM>, <NUM>) of server racks in the second HAC; and
a fourth busway segment that is operable to electrically connect the second PDU to a fourth set of server racks in the second row of server racks in the second HAC, the fourth set of server racks being distinct from the second set of server racks, whereby workloads are assigned to server racks at a row level.