# Patent

## Title
Server rack architecture that facilitates reduced current density

## Abstract

A server rack with vertically stacked shelves is disclosed. The shelves are used for housing loads (e.g. servers) and power supply units. Thus, both the power supply units and the servers are vertically stacked in the rack. An array of vertical and horizontal busses is secured to the back side of the server rack to electrically couple the servers with the power supply units. The arrangement of the PSUs and the busses provides for uniform current density across the server rack. The devices placed on the shelves are accessible and serviceable from the front of the server rack. The server rack can be placed within or secured to a device, system or a server room in a vertical orientation, a horizontal orientation or at an angle.

## Background
TECHNICAL FIELD
The subject disclosure relates to server racks and more particularly to optimizing current distribution by reducing current density within a server rack.
BACKGROUND
Server racks are used to house multiple computer servers and other related loads, and to provide power and communication signals to them. A server rack uses busses to distribute the current generated by power supply units (PSUs) to the loads situated on various shelves of the server rack. In conventional server rack architecture, the PSUs are located on either the top shelf or the bottom shelf of the server rack, and the current generated by them is distributed to the various loads by using a vertical bus. The vertical bus location closest to the PSUs is subjected to maximum current density. The current density progressively decreases at vertical bus locations away from the PSUs. Conventional server rack architecture requires oversized busses that can support the maximum possible current density that can be generated by the PSUs. Oversized busses are undesirable because they require more space and increased material costs than smaller busses.
SUMMARY
The following presents a simplified summary of the specification in order to provide a basic understanding of some aspects of the specification. This summary is not an extensive overview of the specification. It is intended to neither identify key or critical elements of the specification nor delineate any scope of particular aspects of the specification, or any scope of the claims. Its sole purpose is to present some concepts of the specification in a simplified form as a prelude to the more detailed description that is presented later.
According to an implementation of the subject disclosure, a server rack having vertically stacked shelves and vertically stacked PSUs is disclosed. Two vertical busses are secured to the back side of the server rack and are located substantially at the left and right sides of the server rack respectively. Multiple horizontal busses, that are parallel to each other, are coupled between the two vertical busses. Each horizontal bus is coupled to two PSUs and to one or more servers. The server rack as a whole can be oriented in a device, system or room vertically, horizontally or at an angle.



BRIEF DESCRIPTION OF THE DRAWINGS
Numerous aspects, implementations, objects and advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:
FIG. 1 illustrates a front view of a server rack, according to an implementation of the subject disclosure.
FIG. 2 illustrates a rear view of a server rack having vertical bus bars and horizontal busses.
FIG. 3 illustrates a rear view of a server rack having divided horizontal busses.
FIG. 4 illustrates a rear view of a server rack having divided vertical bus bars and divided horizontal busses.
FIG. 5 illustrates a rear view of a server rack having a central vertical bus bar.
FIG. 6 illustrates a rear view of a server rack having a divided vertical bus bar.
FIG. 7 illustrates an exemplary graphical representation of a battery power module for use in a server rack demonstrating architecture for enhanced power distribution.
FIG. 8 illustrates an exemplary isometric graphical representation of a battery power module and a server rack.
FIG. 9 illustrates a flow diagram of an exemplary method for assembling an efficient server rack.
FIG. 10 illustrates an example methodology for hot swapping a server rack component.
FIG. 11 illustrates an exemplary graphical representation of a server rack including separable racks for housing PSUs.



DETAILED DESCRIPTION
Implementations of the subject disclosure are described below with references to the above drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the subject disclosure. It is to be appreciated, however, that the subject disclosure can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the subject disclosure.
As discussed herein, the terms N, N+1 and N+M are used herein according to their ordinary meanings. Also, N, N+1 and N+M are used interchangeably herein. M can be 0 or 1 or another integer number. As discussed herein, components are coupled to one another securely, hinged or removably. Secure and hinged are used with their usual meanings. Removable coupling includes any fastening that provides lateral stability without being permanently fixed. For example, removably coupled components can be removed using a single tool, such as a screwdriver. In a nonlimiting implementation, removable coupling can include mere placement of a component on top of a shelf, whereby gravity and friction or physical objects such as other components provide lateral stability. In a nonlimiting implementation, removable coupling includes the use of a tray that slides. Other nonlimiting examples of secure or removable coupling include adhesives, screws, clips, clamps, interference fits and pins.
As discussed herein, hot swappable means the power supply units can be removed during continuous operation of the other components on the server rack. By having components that are removably coupled, the server rack architecture disclosed herein facilitates components being hot swappable. As discussed herein, a load is a device that uses electrical power or communications from the server rack and is electrically coupled to other components on the server rack. The terms server, load, and component as used herein, are interchangeable. In a nonlimiting implementation, a video monitor is the load. In a non-limiting implementation, multiple servers or loads are placed on each shelf in a server rack.
FIG. 1 illustrates an exemplary front view of a server rack 100. The server rack 100 includes two side posts (1051 and 1052) which are vertically oriented and contain compartments for housing power supply units. A first shelf (1101) is securely coupled to and located toward the upper ends of the posts (1051 and 1052). The first shelf (1101) can extend into the posts (1051 and 1052) and create the compartments for housing the PSUs (1201, 1202). A second shelf (1102) is securely coupled to the posts (1051 and 1052) and is generally located below the first shelf MOO. It is to be understood that any number of shelves (110N) can be coupled to the posts (1051 and 1052) and located above or below other shelves (1101, 1102, 110N) in the rack 100. Furthermore, it is to be understood that any type of secure coupling can be used to attach shelves (1101, 1102, 110N) to posts (1051 and 1052) in a way that fixes their location and provides structural rigidity to the server rack 100.
Servers (1301, 1302, 130N) are placed on top of the shelves (1101, 1102, 110N) respectively and generally placed at the center of their respective shelves, equidistant from the first and second sides. Each shelf (1101, 1102 or 110N) can house one or more servers (e.g. 1301) of same or different form factors. The servers (e.g. 1301, 1302, 130N) can be removably coupled to the shelves (1101, 1102, 110N). In nonlimiting implementations, a load (e.g. 1301 can also include any combination of appliances, data center components, server system components, communication components, AC components, DC components and electronic devices.
The power supply units (or modules) (1201, 1202, 1203, 1204, 120M+1) include power converters and backup power sources. In an implementation, the power distribution units controllers (e.g. 1401 and 1402) provide an AC fuse function or circuit breaker function and are removably coupled to a power control shelf (145) of the server rack 100. Furthermore, removable coupling allows the PDUs (1401 and 1402) to be hot swappable. In an implementation, the power control shelf (e.g. 145) is located above the first shelf (1101). In an implementation, the PDUs (1401 and 1402) provide the initial AC power input connection for the server rack 100. In an implementation, the PDUs (1401 and 1402) are electrically coupled to the power supply modules (1201, 1202, 1203, 1204, 120M+1). In an implementation, the power supply modules (e.g. 1201, 1202, 1203, 1204, 120M+1) convert AC input to DC output. In an implementation, power supply modules (e.g. 1201, 1202, 1203, 1204, 120M+1) are mounted separate and external to server rack 100.
In an implementation, power supply modules (e.g. 1201, 1202, 1203, 1204, 120M+1) are electronic assemblies of batteries coupled to power converters. In an implementation, the power supply modules (e.g. 1201, 1202, 1203, 1204, 120M+1) are removably coupled to the shelves (e.g. 1101, 1102, 110N). Removable coupling allows the power supply modules (e.g. 1201, 1202, 1203, 1204, 120M+1) to be hot swappable. Power supply modules (e.g. 1201, 1202, 1203, 1204, 120N, 120M+1) are electrically coupled to loads (e.g. 1301, 1302, 130N). Power supply modules (e.g. 1201, 1202, 1203, 1204, 120M, 120M+1) invert or transform AC or DC input into AC or DC output for use by the loads (e.g. 1301, 1302, 130N). The server rack 100 can be placed inside or attached to a system, device or room at various orientations including vertically, horizontally or at an angle.
FIG. 2 illustrates a rear view 200 of the power distribution components in an exemplary server rack. Viewed from the back side of the server rack 100, an array of electrical distribution busses (including e.g. 2501, 2502, 2601, 2602, 2701 and 270N) is securely coupled to the server rack 100. The power supply modules (e.g. 1201, 1202, 120M+1) are coupled to horizontal busses (e.g. 2601, 2602, 2603, 2604, 260M and 260M+1) as shown. Busses (2601, 2602, 2603, 2604, 260M and 260M+1) are securely coupled to vertical bus bars (2501, 2502) as shown. Vertical bus bars (2501 and 2502) are also coupled to busses (2701, 2702 and 270N) and to the servers (1301, 1302, 130N). In an implementation, power cables are used in place of bus bars (2501, 2502). In this disclosure, bus bars can be replaced with less rigid busses; for example, busses made of short lengths of cables having lugs and/or locations for forming bolted interconnections. As shown, power supply modules (e.g. 1201, 1202, 1203, 1204, 120M+1) are coupled to distribution busses (e.g. 2601, 2602, 2603, 2604, 260M+1).
The server rack architecture of FIG. 2 provides an uniform distribution of current along the various power distribution busses (including e.g. 2501, 2502). Uniform current distribution results from placing the power supply modules (1201, 1202, 1203, 1204, 120M+1) near the loads (e.g. 1301, 1302, 130N). Lower current density results from supplying each load (e.g. 1301) with the current from one or two power supply modules (e.g. 1201 and 1202) through their respective busses (e.g. 2501, 2502, 2601, 2602 and 2701). As a result, the busses (including e.g. 2501, 2502, 2601, 2602 and 2701) can be a of smaller size to accommodate this uniform and lower distribution of current density. Conventional server rack designs have the current concentrated at the top or at the bottom of the server rack. As such, all of the current used by the loads in the rack flows through a single point, and is then distributed along the rack. Conventional architecture requires the bus to be sized for the largest current load. The subject disclosure allows for smaller bus sizes, which results in reduced material costs. Another benefit of using the server rack architecture shown in FIG. 2 is the improved isolation of component failures. For example, having multiple power supply modules (e.g. 1201, 1202, 1203, 1204, 120M, and 120M+1) and common connecting busses (e.g. 2501 and 2502) provide redundancy that prevents failure of the entire rack 100 upon failure of an individual component. This reduces the size of the effect of certain catastrophic failures on the rack. For example, if one power supply (e.g. 1201) was to fail, it would not cause the entire server rack to fail because the other power supplies (e.g. 1203, 120M) in the rack would remain in operation.
FIG. 3 illustrates a rear view 300 of the power distribution components in an exemplary server rack having divided horizontal busses. As shown, the power supply modules (e.g. 1201, 1202, 1203, 1204, 120M+1, 120M+1) are coupled to busses (e.g. 3601, 3602, 3603, and 3604, 360M, 360M+1). Busses are coupled to the vertical bus bars 3501 and 3502 respectively. Vertical bus bar 3501 is coupled to busses 3701, 3703, 370M Vertical bus bar 3502 is coupled to busses 3702, 3704, 370M+1. Busses 3701, 3703, 370M are coupled to servers 3301, 3303, 330N respectively. Busses 3702, 3704, 370M+1 are coupled to servers 3302, 3304, 330M+1 respectively. Two servers (e.g. 3301 and 3302) are placed on top of a shelf (e.g. 1101). Two servers (e.g. 3303 and 3304) are placed on top of another shelf (e.g. 1102). The servers (e.g. 3301 and 3302) are placed generally equidistant from the center of the rack 100 towards the left and right posts (1051 and 1052). Each of the benefits of using the server rack architecture shown in FIG. 1 and FIG. 2 are common with the server architecture shown in FIG. 3. Furthermore, dividing the bus bars horizontally (e.g. 3701, 3702, 3703, and 3704, 370M, 330M+1) increases the isolation of failed load components.
FIG. 4 illustrates a rear view 400 of the power distribution components in an exemplary server rack having both vertically and horizontally divided busses. Vertical bus bars (e.g. 4501 and 4502) are located above vertical bus bars (e.g. 4503 and 4504) respectively. Eight (8) power supply modules (1201, 1202, 1203, 1204 and 4201, 4202, 4203, 4204) are coupled to eight horizontal busses (3601, 3602, 3603, 3604 and 4601, 4602, 4603, 4604) respectively. As shown, busses 3601, 3602, 3603, and 3604 are coupled to vertical bus bars 4501 and 4502. Also, as shown, busses 4601, 4602, 4603, 4604 are coupled to vertical bus bars 4503 and 4504. Vertical bus bars 4501 and 4502 are coupled to busses 3701, 3702, 3703, 3704. Vertical bus bars 4503 and 4504 are coupled to busses 4701, 4702, 4703, 4704. Busses 3701, 3702, 3703, 3704, are coupled to servers 3301, 3302, 3303, 3304. Busses 4701, 4702, 4703, 4704 are coupled to servers 4301, 4302, 4303, 4304. Each of the benefits of using the server rack architecture shown in FIG. 3 is common to the server architecture shown in FIG. 4. Furthermore, dividing the bus bars both horizontally and vertically further increases the isolation of failed load components.
FIG. 5 illustrates a rear view 500 of an exemplary server rack having a central vertical power distribution bus. An array of electrical distribution busses (e.g. 5501, 5601, 5602, 5701, 5702) is securely coupled to the server rack 100 shown in FIG. 1 and is located at the rear side of the server rack. Two power supply modules 1201 and 1202 are coupled to the buss 5601. Two power supply modules 1203 and 1204 are coupled to the buss 5602. Busses (e.g. 5601, 5602) are coupled to vertical bus bar (e.g. 5501). A central vertical distribution bus (e.g. 5501) is generally located centered between the first and second sides. Vertical bus bar (e.g. 5501) is coupled to horizontal busses (e.g. 5701 and 5702). Bus 5701 is coupled to server 5301. Bus 5702 is coupled to server 5302. The two servers 5301 and 5302 are placed on top of the shelves 5101 and 5102 respectively. The servers are placed generally centered, equidistant from the first and second sides. Each of the benefits of using the server rack architecture shown in FIG. 2 is common with the server architecture shown in FIG. 5. However, the architecture shown in FIG. 5 utilizes less bus materials by having the single vertical bus.
FIG. 6 illustrates a rear view 600 of an exemplary server rack demonstrating architecture including multiple, central, vertical distribution busses (e.g. 5501, 6502). Viewed from the back side of the server rack 100, an array of electrical distribution busses (e.g. 5501, 6502, 5601, 5602, 5701, 5702, 6601, 6602, 6701, 6702) is securely coupled to the server rack 100 at the rear side of the server rack. Four (4) power supply modules 1201, 1202, 1203, 1204 are coupled to horizontal busses 5601, 5602. Four (4) power supply modules 6201, 6202, 6203, 6204 are coupled to horizontal busses 6601, 6602. Busses 5601, 5602 are coupled to vertical bus bar 5501. Busses 6601, 6602 are coupled to vertical bus bar 6501. Vertical bus bars (5501, 6501) are generally located centered between the first and second sides. The first vertical bus bar (5501) is located above second vertical bus bar (e.g. 6502). Vertical bus bars 6501, 6502 are also coupled to horizontal busses (e.g. 5701, 5702, 6701, 6702). Busses 5701, 5702, 6701, 6702 are coupled to servers (e.g. 1301, 1302, 6301, 6302). Four (4) servers (e.g. 1301, 1302, 6301, 6302) are placed on top of shelves (e.g. 5101, 5102, 6101, 6102). The servers are placed generally centered, equidistant from the first and second sides. Each of the benefits of using the server rack architecture shown in FIG. 5 is common with the server architecture shown in FIG. 6. Furthermore, the architecture shown in FIG. 6 provides for additional component isolation by dividing the vertical bus.
FIG. 7 illustrates an exemplary graphical representation 700 of a power supply unit. In an implementation, each power supply module 710N includes a battery 725N (or another type of energy storage device that can be used as a backup power source) and a power converter with uninterruptable power supply 720N. Each battery 725N is removably coupled to a power converter 720N. The battery 725N is accessible from the front side of the server rack 100 and can be removed from the front side of the server rack 100. Removable coupling of the battery 725N includes mechanical and electrical coupling.
In an implementation, the power supply module 710N receives AC input from an AC source 735 through distribution lines 730N. The power supply module 710N provides AC or DC output through distribution lines 740N. In another implementation, the power supply module 710N receives DC input from a DC source 735 through distribution lines 730N. The power supply module 710N provides AC or DC output through distribution lines 740N. Output distribution lines 740N include busses and bus bars. Furthermore, each power supply module 710N sends and receives digital communication through communication lines 750N from a controller 770. In various implementations power inputs and outputs are all AC, or all DC, or a combination thereof. It is to be understood that any combination of electrical inputs and outputs can be used with the server rack architecture 100 and with the power supply modules outlined herein. The power lines 730N and 740N and the communication lines 750N can be implemented by using a power strip 780. The power strip 780 can be vertically secured to the back of the server 100. The power strip 780 distributes both AC and DC power and also facilitates communication between the host 770 and the PSUs (e.g. 710N).
One of the benefits of the power supply module shown in FIG. 7 is improved serviceability. By locating the battery 725N in front of the power converter 720N, the battery 725N is made more accessible from the front of the server rack 100. By having a removable connector between the battery 725N and the power converter 720N, the battery 725N can be hot swapped. By having the AC 730N, DC 740N and digital communication lines connected to the power supply module 710N from the back side of the server 100, the serviceability of the module 710N is made easier. Furthermore, having the AC 730N, DC 740N and digital communication lines coupled to the power supply module 710N from the back side of the rack 100 facilitates the use of the bus components and server rack architecture described herein.
FIG. 8 illustrates an exemplary isometric graphical representation 800 of a PSU tray and a server rack. In an implementation, the PSU tray 810N includes four vertically oriented sides and a bottom. Each of the four vertical sides is coupled to one another at two edges. Each of the four vertical sides is coupled to the edges of the bottom. In nonlimiting implementations, the sides and bottom can be coupled permanently, removably, or hinged as mentioned in this description. The walls and bottom can be of rigid or flexible materials. The walls can be of any shape. In one implementation, the vertical walls are shaped with cutouts to accommodate manipulation of the power supply module. In an implementation, the tray 810N includes details that allow users to grasp the tray from the front of the server rack 100 and remove the tray and a power supply module (e.g. 1201). Nonlimiting examples of these details are handles, knobs or hooks. The details can be mounted to the top, front, first side or second side of the trays. In an implementation, a side is located at the rear of the tray. This rear side may be of any height. In an implementation, removable coupling of the batteries includes the use of a tray 810N having interior dimensions such that a power converter 720 and a battery 725 would fit with minimal clearance and be mechanically retained by any two opposing sides of the tray. It is to be understood that the battery 725 is only one type of backup power source that can be used. Other types of energy storage devices can be used as backup power sources.
FIG. 9 illustrates a flow diagram of an exemplary method for assembling a server rack. According to the methodology shown in the flow diagram 900, at 910, shelves (such as 1101, 1102, and 110N as shown in FIG. 1) are stacked vertically to form the rack. At 920, a first server (such as 1301 as shown in FIG. 1) is located between the first and second power supply modules (such as 1201 and 1202 as shown in FIG. 1) on a first shelf (such as 1101 as shown in FIG. 1). At 930, a second server (such as 1302 as shown in FIG. 1) is located between the third and fourth power supply modules (such as 1203, 1204 as shown in FIG. 1) on a second shelf (such as 1102 as shown in FIG. 1).
At 940, a first bus bar (such as vertical bus 2501 as shown in FIG. 2) is connected to first and third power supply modules (such as 1201 and 1203 as shown in FIG. 2). At 950, a second bus bar (such as vertical bus 2502 as shown in FIG. 2) is connected to second and fourth power supply modules (such as 1202 and 1204 as shown in FIG. 2). At 960, the first bus bar (such as vertical bus 2501 as shown in FIG. 2) is connected to a first server (such as 1301 as shown in FIG. 2) to supply voltage and current to the first server. At 970, the second bus (such as vertical bus 2502) is coupled to a second server (such as 1302 as shown in FIG. 2) to supply voltage and current to the second server.
A benefit of using the method of server rack assembly 900 is the resulting more uniform distribution of lower current density along the various power distribution busses (such as 2501, 260M and 270M shown in FIG. 2). Uniform current distribution results from placing the power supply modules (such as 120N shown in FIG. 2) near the loads e.g. 130N shown in FIG. 1). Lower current results from supplying each load (such as 130N shown in FIG. 2) with the current from one or two power supply modules (such as 120N shown in FIG. 2) through their respective busses (such as 2501, 2502, 260N+1 and 270M shown in FIG. 2). Busses (such as 2501, 260M and 270N shown in FIG. 2) can be a smaller size and adequately accommodate this uniform distribution of lower current density. Another benefit of using the method of assembling server rack architecture shown in FIG. 9 is the improved accessibility to the power supply modules (e.g. 1201 thru M+1 shown in FIG. 2). Being located to the first and second sides and distributed vertically, the power supply modules (1201 thru M+1) are accessible from the front side of the server rack 100 shown in FIG. 1. Another benefit of the method of assembling a server rack shown in FIG. 9 is that multiple power supply modules (e.g. 1201,2,3 shown in FIG. 2) are attached to the common bus bars 2501 and 2502 and the servers (e.g. 130N) shown in FIG. 2. This provides for a redundancy of power. It is to be understood that the rack can be placed or positioned inside a computer system, a device or a server room vertically, horizontally or at an angle. It is to be understood that if the rack is positioned horizontally or at an angle, the devices on the rack must be secured to the shelves such that they don't slide or fall off the rack because of gravity. It is also to be understood that the various shelves and busses of the server rack can be positioned at different angles.
FIG. 10 illustrates an example methodology for hot swapping a server rack component. According to the construction methodology flow diagram 1000, at 1010, a component requiring service is identified. Service as used herein can include, for example, repair, replacement or inspection. At 1020, the component requiring service is removed from the rack. To that end, the component requiring service is turned off and no other components in the rack are turned off. Turning off includes, for example, pushing buttons or sending control signals that deactivate the operations of the component. The primary advantage of hot swapping is that a component is removed and replaced from a system of components without affecting the operation of the other components. The server rack system 100 as discussed herein facilitates hot swapping PDUs (e.g. 1401 shown in FIG. 1) power supply modules (e.g. 120N shown in FIG. 1) and servers (e.g. 130N shown in FIG. 1). It is to be understood that other components can be added to the server rack 100 and can be hot swappable. The component requiring service is also mechanically disconnected from the rack. Mechanical disconnection includes the disassembly of any of the mechanical couplings discussed herein. Prior to or after mechanically disconnecting the component, the component requiring service is electrically disconnected from the rack. Electrical disconnection includes disassembly of any of the electrical couplings discussed herein. At 1030, a new, repaired or replacing component is electrically, mechanically and/or programmatically connected to the rack. Mechanical reconnection includes returning the component to its shelf, tray or otherwise placed into the rack. At 1040, the component is turned on and its operation commences.
FIG. 11 illustrates an exemplary graphical representation 1100 of a server rack with removable PSUs racks. A server component rack 1104 is supported by four corner posts or two sides, vertically oriented to define four sides including a front, a back and two additional sides. The server component rack 1104 houses and physically supports load components (e.g. 1130N, 1133N and 1136N). A PSUs rack 1108 is also shown that houses and physically supports PSUs and related components (e.g. 1140N (e.g. a PDU), 1150N (e.g. a bus) 1120N, (e.g. a PSU)). Additionally, the PSUs rack (or power components rack) 1108 has multiple wheels or casters 1180. The wheels 1180 facilitate the movement of the power component rack 1108 independently of server component rack 1104.
The PDU 1140N receives external AC (or DC) voltage and current, and controls the flow of the input current (e.g. by using fuses or circuit breakers). Power control modules 1140N are connected to power supply modules 1120N. Bus bars 1160N are coupled to power supply modules 1120N and vertical bus bars 1150N. Bus bars 1170N are coupled to vertical bus bar 1150N and loads (e.g. 1130N, 1133N and 1136N). In an implementation, bus bars 1170N are securely coupled to vertical bus bars 1150N and removably coupled to the loads (e.g. 1130N, 1133N and 1136N) such that bus bars 1170N generally travel as parts of the power component rack 1108. In an implementation, bus bars 1175N are securely coupled to the loads (e.g. 1130N, 1133N and 1136N) and removably coupled to the vertical bus bars 1150N such that the bus bars 1175N generally travel with the loads.
The advantages of the implementation of the server rack 1104 and separate power rack 1108 assembly 1100 (assembly) are common with those outlined herein for various implementations. One additional advantage of the assembly 1100 is the mobility of power component racks 1108. For example, when loads on a server rack 1104 require low current, only one power component rack 1108 may be necessary. The additional power component rack 1108 can be disconnected mechanically and electrically from the server component rack 1104 in a first location, and moved to a second location. Such mobility can free space in the first location. Another advantage of such mobility is the opportunity for servicing the battery rack in the second location.
What has been described above includes examples of the implementations. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but it is to be appreciated that many further combinations and permutations of the subject innovation are possible. Accordingly, the claimed subject matter is intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims. Moreover, the above description of illustrated implementations of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed implementations to the precise forms disclosed. While specific implementations and examples are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such implementations and examples, as those skilled in the relevant art can recognize.

## Claims

1. A server rack, comprising:
vertically stacked first and second shelves, wherein the first shelf is located above the second shelf;
first and second vertical busses each coupled to a back side of the server rack;
a first set of multiple power supplies connected at various different locations of the first vertical bus;
a first set of multiple horizontal buses that connect the first vertical bus to a first set of multiple servers, wherein each horizontal bus in the first set of multiple horizontal buses respectively couples the first vertical bus to a respective server from the first set of multiple servers, and wherein the first offset of multiple servers receives power from the first set of multiple power supplies; and
a second set of multiple power supplies connected at various different locations of the second vertical bus;
a second set of multiple horizontal buses that connect the second vertical bus to a second set of multiple servers, wherein each horizontal bus in the second set of multiple horizontal buses respectively couple the second vertical bus to a respective server from the second set of multiple servers, and, wherein the second set of multiple servers receives power from the second set of multiple power supplies.

2. The server rack of claim 1, wherein the first and the second horizontal busses are located at approximately a same height from the bottom of the server rack, and wherein there is an open space between the ends of the first and second horizontal busses that are located towards the center of the server rack.

3. The server rack of claim 1, wherein a fifth horizontal bus couples a first power supply unit to the first vertical bus.

4. The server rack of claim 3, wherein a sixth horizontal bus couples a second power supply unit to the second vertical bus.

5. The server rack of claim 1, wherein each horizontal bus of the first set of multiple horizontal buses and second set of multiple horizontal buses extends from the first vertical bus to the second vertical bus.