Patent Publication Number: US-7715207-B2

Title: Rack architecture and management system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This U.S. patent application is a continuation of U.S. patent application Ser. No. 11/564,151, filed on Nov. 28, 2006, which is a divisional of U.S. patent application Ser. No. 10/783,687, filed on Feb. 20, 2004, which claims the benefit of U.S. Provisional Application No. 60/498,193, filed on Aug. 27, 2003 by inventors Edward Behrens, Tho Tu, Van T. Hua, and David Wang, all of which are hereby incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     Various embodiments of the invention pertain to rack enclosure cabinets for computer and other electrical devices. More particularly, at least one embodiment of the invention relates to a rack architecture with a interface column to reduce cabling in the rack cabinet as well as centralize system management to efficiently monitor and control devices in the rack cabinet. 
     DESCRIPTION OF THE RELATED ART 
     Rack enclosure cabinets have been used to house a plurality of computers and other devices. Such rack cabinets provide a way to house a number of computers and/or other devices in a limited space. Data centers, where large numbers of computers are typically housed, often use numerous cabinets to house various computers, storage devices, and other electronic devices. 
     With the large number of computers and other devices in a data center, rack cabinets are often densely packed with computers and/or other devices. However, each computer and/or device typically has one or more cables for power and signaling. This often creates a large tangle of cables at the rear of the rack cabinet, making it difficult to remove, replace, and/or service computers or other devices in the cabinet rack. 
     Typical rack management solutions concentrate on a single aspect of the management picture and have no common interface or control schema. Some solutions provide remote keyboard, video and/or mouse access over a network or the remote control of power management. However, there are no products that address management of the entire rack cabinet and/or a data center of rack cabinets. The majority of these management solutions and/or products are also not scaleable on a per port basis but rather a plurality of ports at a time (e.g., eight at one time). Thus, it makes it difficult to add functionality and/or resources on an as-needed basis. 
     Additionally, because prior art solutions provide separate management interfaces, it makes it cumbersome to manage, maintain, and monitor a data center with several server racks. 
     SUMMARY OF THE INVENTION 
     One embodiment of the invention provides a fully distributed, scaleable and modular rack architecture and management system. One feature of the invention provides device management throughout the rack with a vertical interface column integrated into the rack cabinet. Within each rack unit (U) of the vertical column, the system delivers connectivity to keyboard, video and mouse (KVM), Universal Serial Bus (USB), and Serial RS232 through a hot-swappable Server Interface Module card (SIM). In one implementation, the vertical column may be populated with 1 to 42 SIM modules (in each U or 1.75″ slot) directly behind the devices (e.g., server, network apparatus, storage devices, etc.) within the rack cabinet thereby eliminating vertical runs of cable typically necessary for management of such devices. 
     The Vertical Column feeds into the Control Module, which is a 1 U chassis typically mounted in the top of the cabinet. In addition to carrying out the core control and switching logic, the Control Module facilitates hot-swappable user card slots. This allows each rack device to be controlled by one or more concurrent users. These users may gain access to devices within a rack locally via a Local Interface Module (LIM) that allows a rack-mountable integrated keyboard, display unit, and mouse to be mounted within and flat panel drawer. Moreover, a Remote Interface Module (RIM) can be deployed within the control unit to provide remote management over a 10/100/1000 TCP/IP network. A client software application may provide access to devices within a server rack using either a standalone security logon or through the primary security scheme provided by the network&#39;s Active Directory protocols. 
     The Control Module may provide additional serial management ports to control devices such as power distribution units, environmental management, cabinet locks and direct connections for managed network hubs or switches. The Control Module may also have a dedicated port for an optional external modem in order to provide dial-up remote management access to the system in the event of a catastrophic network failure. 
     One embodiment of the vertical column provides a smaller integrated column that can economically handle compact options of 14 U, 28 U, or any sub 42 U combination. 
     One feature of the invention provides centralized management of server, network, power and environmental equipment within a rack cabinet to a single IP address. Additionally, an embodiment of the invention provides a scaleable solution that permits adding components and/or devices (e.g., servers, network equipment, etc.) as well as regulates the total number of users accessing those devices. This allows customers to grow their infrastructure without the need to invest in oversized equipment on the initial deployment. 
     One embodiment of the invention may provide low-level connectivity to a combination of input/output devices (e.g., keyboard, video display, mouse, serial interface and/or universal serial bus (USB) for equipment within a rack. These input/output devices can be addressed locally within the rack or remotely over an IP Network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating the various components of a Rack Management System according to one embodiment of the invention. 
         FIGS. 2 and 3  illustrate a Vertical Column mounted in a Rack Cabinet according to one embodiment of the invention. 
         FIG. 4  illustrates a Vertical Column with Server Interface Modules installed therein according to one embodiment of the invention. 
         FIG. 5  illustrates a Control Unit according to one embodiment of the invention. 
         FIG. 6  illustrates how the Vertical Column is coupled to a Control Unit according to one embodiment of the invention. 
         FIG. 7  is a block diagram illustrating the components of a Server Interface Module according to one embodiment of the invention. 
         FIG. 8  illustrates one embodiment of a hybrid cable that may be used to couple a server to a server interface module according to one embodiment of the invention. 
         FIG. 9  is a block diagram illustrating the Cascade Server Interface Module according to one embodiment of the invention. 
         FIG. 10  is a block diagram illustrating a Backplane Module according to one implementation of the invention. 
         FIG. 11  is a block diagram illustrating a Midplane Module according to one embodiment of the invention. 
         FIG. 12  is a block diagram illustrating a Control Module according to one embodiment of the invention. 
         FIG. 13  is a block diagram illustrating a Local Interface Module (LIM) according to one embodiment of the invention. 
         FIG. 14  is a block diagram illustrating Remote Interface Module (RIM) according to one embodiment of the invention. 
         FIG. 15  is a block diagram illustrating the User Cascade Interface Module according to one embodiment of the invention. 
         FIG. 16  illustrates one embodiment of a connection arrangement between a slave system cascaded to a master system. 
         FIG. 17  is a block diagram illustrating a Dual Redundant Power Supply (DRPS) system according to one embodiment of the invention. 
         FIGS. 18-20  illustrate a user interface device that enables an operator to access and manage devices communicatively coupled to a Control Unit according to one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description numerous specific details are set forth in order to provide a thorough understanding of the invention. However, one skilled in the art would recognize that the invention may be practiced without these specific details. In other instances, well known methods, procedures, and/or components have not been described in detail so as not to unnecessarily obscure aspects of the invention. 
     In the following description, certain terminology is used to describe certain features of one or more embodiments of the invention. For instance, the term “data center” refers to a collection of one or more computers, servers, storage device, and/or network equipment in one or more racks, either in the same location and/or linked by a network. The term “rack”, as in rack cabinet, server rack, etc., refers to any physical structure that houses one or more servers, storage devices, and/or network devices. The term “interface column” includes columns with electrical couplers that may be positioned in any orientation, including vertically. 
     Generally, one embodiment of the invention provides a centralized rack management system bridging the fractured proprietary management protocols from different vendors and across various data center products. One feature of the rack management system reduces or eliminates the vertical runs of management cables within the server rack. Another feature of the rack management system provides a “pay as you grow” server rack and management platform that can be customized to each specific application. 
     According to one implementation of the invention, each rack cabinet may be associated with a corresponding Internet Protocol (IP) address. This permits accessing, controlling, and managing devices, such as servers, data storage devices, and/or network equipment, housed within each rack cabinet. Such feature opens the ability not only to manage servers through a common interface, but also to integrate capabilities such as asset management, security management and power management. 
     One aspect of the invention addresses the issues of high-density server and network device management. Management has become fractured with various proprietary management solutions from hardware manufacturers of server and network devices. With the deployment of grouped racks throughout a data center, the invention also centralizes management of servers, power, and environmental conditions within each individual rack cabinet. 
     Conventional rack management solutions typically require a user to terminate out-of-band management cables within a specific horizontal plane of a rack cabinet (i.e., rack unit  23  of  42 ). One embodiment of the present invention employs a vertical column to distribute the management hardware connectivity into a vertical plane thereby eliminating the issues of cabling and cable management. Additionally, the invention provides a completely scaleable solution for management of a plurality of devices (e.g., one to forty-six devices—forty-two keyboard, video, mouse, USB, serial, plus four additional serial devices) within the rack and also enable one or more users to address or access the devices simultaneously. 
     One implementation of the invention can be scaled and/or configured to handle  1 -N devices, where N is the maximum number of devices (e.g., servers, network equipment, data storage devices, etc.) that can fit into a rack. Such system may be configured so that a single user interface device mounted in a first rack cabinet permits an operator to monitor and/or control equipment and/or computer servers located in both the first rack cabinet and other rack cabinets. 
       FIG. 1  is a block diagram illustrating the various components of a rack management system according to one embodiment of the invention. In this implementation the management system includes two subsystems, a Vertical Column  102  and a Control Unit  104 . They are communicatively coupled, via a cabling system for instance, to transfer digital signals, analog signals and power. 
     The Vertical Column  102  holds one or more switching Backplane Modules (BM)  106 . Each Backplane Module  106  may house up to N (e.g., N is 14) Server Interface Modules (SIM)  108 . Alternately, where the rack unit location does not have a rack device, the Server Interface Modules  108  can be replaced with Server Cascade Modules  110  to extend the control to slave systems. A Midplane Module (MM)  118  is communicatively coupled to each Backplane Module  106  to merge the multiple backplane buses  112 . 
     Each Server Interface Module  108  is in close proximity to the rack devices  114  (e.g., server or network equipment) assigned to its rack unit location. The Server Interface Module  108  is communicatively coupled to its corresponding server  114  via a short cable  116 . In one implementation of the invention a short cable  116  carries the set or subset of interfaces including video (e.g., VGA), PS/2 keyboard/mouse, universal serial bus (USB), and serial RS232. The Server Interface Module  108  has the necessary hardware and software to emulate the physical devices that the server  114  expects. That is, the Server Interface Module  108  merges/consolidates a variety of digital signals into a single high-speed bus along with a separate analog video line. 
     The Backplane Module  106  can be configured to selectively switch the high-speed digital “pipe” and video from each Server Interface Module to each of the N (e.g., N is 4) user buses. At the top end of the vertical column  102  there is a Midplane Module  118  which performs a second level switch selection of Server Interface Module signals in order to consolidate the Server Interface Module signals  112  from all of the Backplane Modules  106  and connect to each of the N user buses  130 . In addition to this high-speed data and analog video switched path to each server there is also a serial bus that links all modules (e.g., SIMs, BMs, MM) to provide operational and maintenance (management) control by the Control Module (CM)  120  inside the control unit  122 . 
     The Control Unit  122  houses a Control Module  120 , Single Board Computer (SBC)  124 , and Dual Redundant Power Supply (DRPS)  126 . The Control Module  120  houses a backplane system that allows User Modules (UM)  128  to be plugged in. There are at least three different types of User Modules: Local User Interface Module (LIM), Remote User Interface Module and the User Cascade Interface Module (UCIM). The Control Module  120  has multiple processors that manage and control all the modules (e.g., SIM, BM, MM, UM) and provides the network interface for remote management. Through the Network Interface  140  the data path to the servers  114  and the management bus are extended beyond the confines of the local system. 
     The Dual Redundant Power Supply  126  includes two identical power sources  132  and  134 , from the AC input all the way to the output DC voltage, which are combined with proper isolation for continued normal operation in the event of failure on one of the power sources. 
     The Single Board Computer  124  may be a self-contained module with enough processing power, and resources (e.g., RAM, mass storage, network controller, etc.) to run an embedded operating system (e.g., Microsoft Windows XP™) with high-powered applications. According to one implementation of the invention, software operating in the Single Board Computer  124  enables automated self-configuration and provisioning of the managed servers  114 . The Single Board Computer  124  executes applications that continuously gather data from the servers  114 , receiving control events from the outside world and affecting changes of state and configurations within. The Single Board Computer  124  performs the above tasks, which are usually subordinated to the decision making process and implementation of an IT specialist. 
     A Server Cascade Module  110  can replace one of the Server Interface Modules  108 , with the purpose of controlling other slave systems  150 . The slave systems may be configured with User Cascade Interface Modules to allow the control by the master system  122 . The connection between the master system  122  and a slave system is via one or more cables  152 . In addition to the server resources of the master system, once the slave system is coupled to the master system all the server resources from the slave system are also available to the master system. In one implementation, a master system may have a cascade module  110  coupled to a User Cascade Interface Module in a Control Unit of a slave system to permit control and/or monitoring of the slave system by the master system. 
       FIGS. 2 and 3  illustrate a Vertical Column mounted in a Rack Cabinet according to one embodiment of the invention. In one implementation of the invention, the rack cabinet  202  includes a rear portion  204  with rails or brackets  206  in which a Vertical Column  208  can be secured. The Vertical Column  208  can be placed at various positions along the rails  206 . The rack cabinet  202  also defines a space  210  in which one or more devices, such as servers, network equipment and/or other devices, may be mounted. 
     According to one embodiment of the invention, in order to support the Vertical Column  208 , the rack cabinet  202  includes two or more mounting brackets  206 , that may span a standard 19″ rack cabinet. Each bracket  206  may be symmetrical and 1 U in height. In one implementation of the invention, one bracket  206   a  is mounted behind the first rack slot (e.g., unit number  1 ) and another bracket  206   b  is mounted behind the last rack slot (e.g., unit number  42 ). The brackets  206  are coupled to the mounting supports of the rack cabinet  202  and the Vertical Column  208  is set into the keyhole  216  that provides the optimal position within the rack cabinet  202  to couple the rack devices (e.g. servers, network equipment, storage devices, etc.). There may be a plurality of keyhole mount points  216  along the length of the brackets  206 . 
     According to one implementation of the invention, the Vertical Column  208  is a 42 U chassis that has a cross section of approximately 3.3 inches by 3.75 inches. Each U in the Vertical Column  208  contains a slot that can be filled with either a Server Interface Module  108  for providing device access, a Cascade Module  152  or a blank cover. One or more Backplane Modules  106  may be located in the Vertical Column  208  to receive the Server Interface Modules  212  ( FIG. 1 ,  108 ). The Backplane Modules  106  are electrically coupled to the Midplane Module  214  ( FIG. 1 ,  118 ;  FIG. 4 ,  404 ) by cables and/or buses inside the Vertical Column  208 . 
     The Vertical Column  208  may be configurable to provide different numbers of U slots. For example, the Vertical Column  208  could be reduced to 28 U or 14 U or any sub 42 U combination height. Consequently, the number of Backplane Modules within the Vertical Column  208  may also be changed as necessary. 
       FIG. 4  illustrates a Vertical Column  208  with Server Interface Modules  212  installed therein according to one embodiment of the invention. The Vertical Column  208  houses modular Server Interface Modules  212  along each IU section. The Server Interface Modules  212  are coupled to connectors on one or more Backplane Modules  402  that are arranged along the rear of the Vertical Column  208 . Such architecture helps reduce the length of the interface cables communicatively coupling the servers or other devices mounted in the rack cabinet  202  and their corresponding Server Interface Modules  212 . As previously discussed, the overall Vertical Column  208  location may also be adjustable along the support rails  206  to further minimize the distance between the Vertical Column  208  and the servers or devices within the rack cabinet  202 . 
     The Server Interface Modules  212  may be field and user installable to allow for growth and flexibility. For example, a user may add Server Interface Modules  212  to the Vertical Column  208  as servers and/or network equipment is added to a rack cabinet  202 . Additionally, the Vertical Column  208  may also be used for adding mechanism to house additional cables for the rack cabinet  202 , such as network wiring and/or other types of cables. 
       FIG. 5  is a Control Unit  502  (illustrated as  122  in  FIG. 1 ) according to one embodiment of the invention. The Control Unit  502  includes a Dual Redundant Power Supply  504  to provide failsafe operation and one or more Single Board Computers  506  to implement the enhanced system features. Additionally, the Control Unit  502  may also include one or more Control Modules  510  and one or more User Modules  508  to manage the communication interface with servers and other devices in the rack cabinet  202 . A plurality of User Modules  510  may serve to provide local, remote and/or cascaded access to Server Interface Modules ( FIG. 1 ,  108 ) through the Control Unit  502 . The User Modules and Control Modules  508  may be separate components that can be installed in the field to allow for growth flexibility. 
       FIG. 6  illustrates how the Vertical Column  208  is coupled to a Control Unit  502  according to one embodiment of the invention. The top of the Vertical Column  208  provides a power connection and signal connection to the Control Unit  502 . One or more power and/or communication cables  602  are coupled from the Control Unit  502  to a Midplane Module  404  attached to the Vertical Column  208 . 
     In one implementation of the invention, the control unit  502  may be installed inside of the rack cabinet  202 , above the Vertical Column  208 , occupying a 1 U space. Since it is in an area that is above and out the server and network equipment U space, it is optimal to bring out all external interfaces there for clutter free cabling. 
       FIG. 7  is a block diagram illustrating the components of a Server Interface Module  700  (illustrated as  108  in  FIG. 1 ) according to one embodiment of the invention. The Server Interface Module  700  (also illustrated in  FIG. 4  as  212 ) is a small electronic board or card that can be plugged into an interface in the Vertical Column  208 . A plurality of Server Interface Modules  700  may be distributed along the Vertical Column  208  (as illustrated in  FIG. 4 ). 
     One purpose of the Server Interface Module  700  is to reduce the number of cables that run along the back of a rack cabinet  202 . The Server Interface Module  700  reduces the number of cables that would otherwise run along the back of a rack cabinet  202  by concentrating a plurality cables into a single, multiple use cable. The Server Interface Module  700  has an interface  701  that plugs into a bus running along the backplane of the Vertical Column  208 . The backplane bus carries a plurality of different signal, such as Board ID, TTL signals, Universal Serial Bus (USB), and RGB video and synchronization, to and from the Server Interface Module  700 . These signals may be concentrated into a single interface to couple them to a device (e.g., server, network equipment, storage equipment, etc.) in a rack cabinet. 
     A hybrid cable may be used to bundle all of the signals into a single cable interface at the Server Interface Module  700  end while providing a plurality of standard interfaces at the server or network equipment end.  FIG. 8  illustrates one embodiment of a hybrid cable  800  that may be used to couple a device, e.g., server or network equipment, to a Server Interface Module according to one implementation of the invention. This hybrid cable  800 , along with the Vertical Column  208 , reduces the number of individual cables that would otherwise need to run to each server in a rack unit. 
     According to one implementation of the invention, the hybrid cable  800  includes a connector  802  at a first end to couple to a Server Interface Module. At the opposite end  803 , the hybrid cable  800  splits into multiple cable interfaces. For example, the second end of the hybrid cable  800  may be split into universal serial bus (USB) interface  804 , a keyboard connector  806 , a video connector  808 , a mouse connector  810 , and a serial port connector  812 . 
     According to one implementation of the invention, the connector  802  is a twenty-five (25) pin connector in which pins are allocated such that all connectors at the second end  803  can be adequately supported. For example, the following table illustrates one scheme for combining various connectors into a hybrid twenty-five pin cable connector. 
     
       
         
           
               
               
             
               
                   
               
               
                 Twenty-five pin connector 
                 Corresponding Signal 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 18 
                 RS232 - Rx Data 
               
               
                 19 
                 RS232 - Tx Data 
               
               
                 20 
                 RS232 - Signal Ground 
               
               
                 25 
                 USB - Power 
               
               
                 23 
                 USB - Data + 
               
               
                 24 
                 USB - Data − 
               
               
                 22 
                 USB - Ground 
               
               
                 7 
                 Keyboard - Data 
               
               
                 6 
                 Keyboard - Signal Ground 
               
               
                 9 
                 Keyboard - Power (+5 V) 
               
               
                 8 
                 Keyboard - Clock 
               
               
                 12 
                 Mouse - Data 
               
               
                 6 
                 Mouse - Signal Ground 
               
               
                 13 
                 Mouse - Power (+5 V) 
               
               
                 11 
                 Mouse - Clock 
               
               
                 1 
                 Video - Red 
               
               
                 2 
                 Video - Green 
               
               
                 3 
                 Video - Blue 
               
               
                 14 
                 Video - Red Signal Return 
               
               
                 15 
                 Video - Green Signal Return 
               
               
                 16 
                 Video - Blue Signal Return 
               
               
                 17 
                 Video - Synchronization Ground 
               
               
                 21 
                 Video - DDC Clock 
               
               
                 10 
                 Video - DDC Data 
               
               
                 4 
                 Video - Horizontal Synchronization 
               
               
                 5 
                 Video - Vertical Synchronization 
               
               
                   
               
            
           
         
       
     
     In this manner, all twenty-five (25) pins of the connector  802  are used to electrically couple to connectors  804 ,  806 ,  808 ,  810 , and  812 . 
     Referring again for  FIG. 7 , the Server Interface Module  700  may include a plurality of components to process and/or manage the signals across the Server Interface Module  700 . A microcontroller  702  receives a Board ID signal  703  and determines if particular signals are addressed to it. If so, a management bus  704  carries TTL serial signals  705  to and from the microcontroller  702 . This bus  704  may be used to carry control signals to and/or from a remote system. The keyboard and/or mouse ports  706  and  708  of a server coupled to the Server Interface Module  700  are handled by peripheral processor  710  so that it can be transferred to processor  712  and then may be used to carry them to a remote system. Additionally, one or more peripheral processors  710  and  712  may process and transfer signals between the backplane of the vertical column and the server coupled to the Server Interface Module  700 . For instance, the peripheral processors  710  and  712  may receive and transmit USB signals to and from the backplane, and convert it to one or more signals to the server ports, such as RS232 port  714  signals or another USB port  716  signal. Other signals, such as the video signal from the server&#39;s video port  718 , may pass through the Server Interface Module to the Backplane  701 , undisturbed. Microcontroller  702  has access to all programmable devices (I2C EEPROM, PS2 processors) in the Server Interface Module, it can also communicate with the rest of the processors in the Server Interface Module board  700  (USB processor, PS2 processors). These are important features that allow the self-building and configuring of the Server Interface Module  700  during manufacturing. 
     The Server Interface Module  700  may be hot-swappable to permit expanding the number of modules in a Vertical Column without the need to shut off all devices in a rack cabinet connected to the Vertical Column. Such hat-swappable feature is made possible by detect-and-enable protection circuitry throughout the modules of the rack system monitoring software that identifies when new devices have been connected or come online and enabling them through the protection circuitry. 
       FIG. 9  is a block diagram illustrating the components of a Server Cascade Interface Module  900  (illustrated as  110  in  FIG. 1 ) according to one embodiment of the invention. The Server Cascade Interface Module  900  is a small electronic board or card that can be plugged into an interface in the Vertical Column  208 . A plurality of Server Cascade Interface Modules  900  may be distributed along the Vertical Column  208  (as illustrated in  FIG. 4 ). 
     One purpose of the Server Cascade Interface Module  900  is to extend the control and access of a first system to other slave systems. The Server Cascade Interface Module  900  has an interface  901  that plugs into a bus running along the backplane of the Vertical Column  208 . The backplane bus carries a plurality of different signal, such as Board ID  903 , TTL signals  905 , Universal Serial Bus (USB), and RGB video and synchronization, to and from the Server Cascade Interface Module  900 . These signals may be concentrated into a single interface  916  to couple them to a User Cascade Interface Module ( FIG. 15 ,  1500 ) that resides in a slave system. 
     A special or standard off-the-shelf cable may be used to bundle all of the signals into a single or dual cable interface(s) that interconnects the Server Cascade Interface Module  900  to the slave&#39;s User Cascade Interface Module ( FIG. 15 ,  1500 ). The design of the Video driver  918  and the Data Serializer Driver/Receiver  914  in conjunction with the Connector Interface  916  in the Server Cascade Interface Module  900 , reduces the number of individual cables that would otherwise need to run between cascaded rack units. 
     The Server Cascade Interface Module  900  may include a plurality of components to process and/or manage the signals across the Server Cascade Interface Module  900 . A microcontroller  902  receives a Board ID signal  903  and determines if particular signals are addressed to it. If so, a management bus  904  carries TTL serial signals  905  to and from the microcontroller  902 . This bus  904  may be used to carry control signals to and/or from a remote control system. Additionally, one or more peripheral processors  910  and  912  may process and transfer signals between the backplane of the Vertical Column and the slaved rack unit coupled to the Server Cascade Interface Module  900 . For instance, the peripheral processors  910  and  912  may receive and transmit USB signals to and from the backplane, and convert it to one or more signals to the Data Serializer Driver/Receiver  914  and to the Cascaded Connector  916 . Other signals, such as the video signal from the Cascaded Connector  916 , may pass through the Video Receiver/Driver  918  to the Backplane  901 , undisturbed. Microcontroller  902  has access to all programmable devices (e.g., I2C EEPROM, Data Serializer program) in the Server Cascade Interface Module  900 , it can also communicate with the rest of the processors in the board: USB processor  910 , Data Serializer  914 . These are very critical features that allow the self-building and configuration of the board during manufacturing. 
     The Server Cascade Interface Module  900  may be hot-swappable to permit expanding the number of modules in a Vertical Column without the need to shut off all devices in a rack cabinet connected to the Vertical Column. Such hot-swappable feature is made possible by detect-and-enable protection circuitry throughout the modules of the rack system in conjunction with the monitoring software that identifies when new devices have been connected or come online and enabling them through the protection circuitry. 
       FIG. 10  is a block diagram illustrating a Backplane Module  1000  according to one implementation of the invention. The Backplane Module  1000  may be located within the Vertical Column and provide one or more interfaces in which to couple one or more Server Interface Modules ( FIG. 1 ,  108 ;  FIG. 7 ,  700 ). The Backplane Module  1000  is a switch that allows Server Interface Module cards ( FIG. 1 ,  108 ;  FIG. 7 ,  700 ) to plug to the connectors  1002  for power and routing of signals to the proper destination user module. In one implementation of the invention, each Backplane Module  1000  is segmented to handle up to fourteen (14) Server Interface Module cards ( FIG. 1 ,  108 ;  FIG. 7 ,  700 ) for flexibility in arranging different product configurations. 
     A Backplane Module  1000  may include a micro-controller  1004  that controls a plurality of switches  1006 ,  1008 , and  1010  to select one of a plurality of Server Interface Modules ( FIG. 1 ,  108 ;  FIG. 7 ,  700 ) that may be coupled to the Backplane Module  1000  via connectors  1002 . That is, the sync selector  1006  selects one of a plurality of synchronization signals from the Server Interface Modules ( FIG. 1 ,  108 ;  FIG. 7 ,  700 ) coupled to connectors  1002 , the video switch  1008  selects one of the video signals coming from the Server Interface Modules, and the USB switch  1010  selects one of the USB signals from the Server Interface Modules. Signals from a management bus interface  1012  are transferred to and from the micro-controller  1004  and directly to a second management bus interface  1014  to the Server Interface Modules. The Backplane Module  1000  may also include a Server Interface Module detect-and-enable unit  1016  to detect when a Server Interface Module ( FIG. 1 ,  108 ;  FIG. 7 ,  700 ) is coupled to the connectors  1002  and enable operation of that Server Interface Module. A module-reset unit  1018  permits the Backplane Module  1000  to reset a Server Interface Module when instructed to do so. 
       FIG. 11  is a block diagram illustrating a Midplane Module  1100  (illustrated as  118  in  FIG. 1 ) according to one embodiment of the invention. The Midplane Module  1100  is a switch that concentrates the signals from the different Backplane Modules  106  ( FIG. 1 ) into a single bus to the Control Module  120  ( FIG. 1 ). The Midplane Module  1100  has a similar layout as the Backplane Module  1000 . A micro-controller  1104  controls signals to and from the Midplane Module  1100 . The micro-controller  1104  receives control signals over the management bus  1112  and configures the selector  1106  and switches  1108  and  1110  accordingly to enable signal transmissions to and from a particular Backplane Connector  1120 . The Midplane Module  1100  may also include a backplane detect-and-enable unit  1116  to detect when a Backplane Module ( FIG. 10 ,  1000 ) is present at a Backplane Connector  1120  and enable operation of that Backplane Module. A module-reset unit  1118  permits the Midplane Module  1100  to reset a Backplane Module ( FIG. 10 ,  1000 ) when instructed to do so. 
     The Midplane Module  1100  helps ease the cabling requirements between the Vertical Column  102  and the Control Module  120  ( FIG. 1 ). That is, rather than having multiple cables running from each Backplane Module ( FIG. 1 ,  106 ) to the Control Module  120 , a single cable may be used between the Control Module cable connector  1122  and the Control Module connector  130  ( FIG. 1 ). 
       FIG. 12  is a block diagram illustrating a Control Module  1200  (illustrated as  120  in  FIG. 1 ) according to one embodiment of the invention. The Control Module  1200  provides the main switching control unit and user interface system. According to one implementation of the invention, the Control Module  1200  is part of the Control Unit ( FIG. 1 ,  122 ), which is 1 U in height. The Control Module  1200  has the board detect feature and separate user module busses  1202 , because of this and of software support, the User Modules ( FIG. 1 ,  128 ) may be hot-swappable to permit expanding the number of User Modules ( FIG. 1 ,  128 ) in a Control Unit ( FIG. 1 ,  120 ;  FIG. 5 ,  502 ) without the need to shut off the Control Unit ( FIG. 1 ,  120 ;  FIG. 5 ,  502 ), the Vertical Column and/or the devices in a rack cabinet connected to the Vertical Column. 
     One implementation of the Control Module  1200  includes a plurality of user card slots or connectors  1202  which permit multiple users to simultaneously access servers via the Control Module  1200 . A mix of Local Interface Modules (LIM), Remote Interface Modules (RIM), and User Cascade Interface Module (UCIM) can be plugged into the user card connectors  1202  and provide access to the Midplane Module  118  ( FIG. 1 ) via connector  1204 . The Control Module&#39;s Control Processors  1218  manages the Midplane via interface  1206  and the User Modules via serial controller  1208 . The network processor  1212  provides the network access for the system, it bridges between the external network via  1220  to the User Modules via  1210  and via  1214  to Control Processor  1218 . The Control Processor  1218  also extends the management functions to external rack infrastructure such as: fan, intelligent power strip for servers, UPS, etc, all via the serial interfaces  1214 . Both the network processor  1212  and the Control Processor  1218  share a data flash storage  1216  to hold all sorts of non-volatile information. 
     The Control Module  1200  may also include a plurality of connectors and/or interfaces, such as RJ45 connection, a 10/100/1000 Mb link to a network, a 10/100 Mb link for to the system management bus. 
       FIG. 13  is a block diagram illustrating a Local Interface Module (LIM)  1300  according to one embodiment of the invention. The Local Interface Module  1300  is a type of user card that can be plugged into the User Module Connectors  1202  of the Control Module  1200 . The Local Interface Module  1300  delivers local access of the servers coupled to the Vertical Column. 
     According to one implementation of the invention, the Local Interface Module (LIM)  1300  may include a microprocessor subsystem  1302  having a processor and memory. The Local Interface Module  1300  may include one or more interface ports or connectors for a keyboard interface  1304 , mouse interface  1306 , a video interface  1308 , and one or more USB interfaces  1310  and  1312 . The keyboard interface  1304 , mouse interface  1306  permit a user to provide input to the Local Interface Module while the USB subsystem  1314  and  1316  and interfaces  1310  and  1312  enable USB-compliant devices to be connected to the Local Interface Module  1300 . The video subsystem  1318  and  1320  and interface  1308  permits connection of an output device, such as a display unit, where a user may view the applications being executed on the Local Interface Module  1300  as well as access information and/or applications from one or more user-selected servers. For example, the Local Interface Module  1300  may provide an on-screen display that allows a user or operator to navigate the attached systems (Control Unit, Vertical Column, Midplane Module, Backplane Modules, servers, etc). 
     Used in conjunction with system management software, the Local Interface Module  1300  provides keyboard, video, and mouse access to the Vertical Column and all of the components electrically coupled thereto. 
     Additionally, the Local Interface Module  1300  may provide a terminal emulator allowing users to manage and configure serial devices such as routers or managed switches. The Local Interface Module  1300  may also support optional USB device sharing. This can be used for peripheral device consolidation and/or biometric security devices. 
     According to one implementation of the invention, USB device sharing provides the ability to attach a single or several USB peripheral devices to the local management card of the server rack. The servers in the server rack may then have access to the peripheral devices. This permits using a single device, e.g., a CD-ROM, per server rack as opposed to the current trend of integrating a separate device, e.g., a CD-ROM, into each server or computer. In another implementation, card readers and/or biometric readers may be used to provide server authentication. Instead of having a single authentication device per server, or a separate USB switch in each server dedicated to support an external authentication device, the server rack management system can share that authentication or peripheral device (e.g., card reader, biometric reader, etc.) with each connected server. These USB devices would be connected to the Local Interface Module  1300  while the switching through the column would provide a connection to any of the servers connected to the Server Interface Module  1300  in the column. 
       FIG. 14  is a block diagram illustrating Remote Interface Module (RIM)  1400  according to one embodiment of the invention. A Remote Interface Module  1400  allows a user or operator to navigate the attached systems (e.g., Control Unit, Vertical Column, Midplane Module, Backplane Module, servers, etc.) over an IP network. The Remote Interface Module  1400  is a type of user card that can be plugged into the User Interface Module connectors  1202  of the Control Module  1200 . The Remote Interface Module  1400  includes a micro-controller  1402 , in conjunction with a USB subsystem  1404  and video subsystem  1406  and  1408 , translates the signals from the Control Module interface  1202  into IP packets and transfers the data over the Ethernet interface  1410  to the network port  1220  of the control module  120 . 
     In one implementation of the invention, up to four Remote Interface Module  1400  cards may be installed in a control module to provide a 4×N switch access, where N can typically be forty-two (42). The Remote Interface Module  1400  may digitize video signals and packetize it along with other digital data (e.g., USB and/or management data) into IP packets to be sent to remote locations via the Internet. 
       FIG. 15  is a block diagram illustrating User Cascade Interface Module (UCIM)  1500  according to one embodiment of the invention. A UCIM  1500  allows the user or operator in an external master rack unit to navigate the attached slave systems (e.g., Control Unit, Vertical Column, Midplane Module, Backplane Module, servers, etc.) over the cascade cable interconnection ( FIG. 16 ,  1602 ). The User Cascade Interface Module  1500  is a type of user card that can be plugged into the User Module connectors  1202  of the Control Module  1200 . The User Cascade Interface Module  1500  includes a micro-controller  1502 , in conjunction with a USB processor  1504  and video receiver/driver  1506 , translates the signals from the control module interface  1202  into Data Serializer driver  1508  and the Cascade Connector  1510  and transfers the data over the cascade cable bundle ( FIG. 16 ,  1602 ). In one implementation of the invention, a Cascade Interface Module ( FIG. 15 ,  1500 ) is configured to send reconditioned analog video and digital data to an external master rack unit, in a point-to-point communication scheme, to enable a user or operator in the external master rack unit to navigate the attached slave systems. 
     In one implementation of the invention, up to four User Cascade Interface Module cards ( FIG. 15 ,  1500 ) may be installed in a slave Control Module ( FIG. 1 ,  120 ) to provide a 4×N switch access to the master rack unit, where N can typically be forty-two (42).  FIG. 16  illustrates one embodiment of a connection arrangement between a slave system cascaded to a master system. The User Cascade Interface Module  1600  in Control Unit  1601  is slaved to a Server Cascade Module ( FIG. 16 ,  1604 ) in the master Vertical Column  1606 , through a cascade cable  1602 . In this manner, the Control Unit  1608 , located in a first rack unit, may control the equipment and/or servers coupled to Control Unit  1601  and the slave Vertical Column  1610  located in a second rack unit. 
       FIG. 17  is a block diagram illustrating a Dual Redundant Power Supply (DRPS) system  1400  (illustrated as  126  in  FIG. 1 ) according to one embodiment of the invention. The system is fed with a dual AC input sources  1702  and  1704  into redundant power supplies  1706  and  1708 . This allows separate AC feeds  1702  and  1704  to enter the unit  126  providing protection against both a power distribution unit failure and a power supply module failure. In the event of a power supply failure, the Control Unit  122  notifies the user, allowing a scheduled maintenance period to be set. A power distribution module  1710  provides a DC power output from the redundant power supplies  1706  and  1708  feed the control module  120 , the Single Board Computer  124 , the Vertical Column  102  ( FIG. 1 ), and other devices. 
     According to one embodiment of the invention, a user interface device is provided that enables an operator to access and manage devices communicatively coupled to the Control Unit  122 , including the Single Board Computer  124 , Control Module  120 , Midplane Module  118 , Vertical Column  102 , Backplane Modules  106 , Server Interface Modules  108 , power supplies  126 , and servers  114 . In one implementation, the user interface device may be IU-high enclosure including a flat panel display unit, a keyboard and a touchpad system that mounts in a standard rack mount cabinet. This system allows for direct connectivity to a Local Interface Module in order to access and manage a system locally.  FIGS. 18-20  illustrate a user interface device that enables an operator to access and manage devices communicatively coupled to the Control Unit  122  according to one embodiment of the invention.  FIG. 18  illustrates the top and side views of the user interface device  1800 . The dimensions of the user interface device  1800  are such that, in one position, it fits within a single U space of a rack unit. The user interface device  1800  may be coupled to rails  1802  that permit the user interface device  1800  to slide in and out of the rack unit.  FIG. 19  illustrates a perspective view of the user interface device  1800  in a closed position.  FIG. 20  illustrates a second perspective view of the user interface device  1800  in an open position. The user interface device  1800  may include a display unit  2002 , a keyboard  2004 , and a pointing device  2006  to permit a user to operate software programs that provide control over other rack mounted devices. 
     According to various embodiments of the invention, one or more user interfaces device  1800  may be mounted in one or more rack cabinets to permit users to access equipment and/or servers in a plurality of networked rack cabinets. For instance, a single user interface  1800  may enable first user to access a first set of servers in one or more rack cabinets while enabling a second user to access a second set of server in one or more rack cabinets. 
     In yet another implementation of the invention, a user may remotely access, control, and/or monitor equipment and/or servers in one or more rack cabinets. For example, using network interface  140 , a user may access a control unit  122  from which local and networked servers in one or more rack cabinets may be controlled, monitored, and/or accessed. 
     Another feature of the invention provides an application that may be executed on a remote terminal to access on or more systems in a rack unit (e.g. Single Board Computer, Control Module, Midplane Module, Backplane Module, Server Interface Module, or servers) over an IP based network. One feature of the application allows a user to log onto the system and authenticate across the network&#39;s Active Directory (AD) to determine to what devices the user may have management access and/or read-only access. The application may provide a graphical user interface of the management system and allow for key sequences to be sent to the remotely connected systems. 
     Yet another feature of the invention provides centralization of security management. Typically, each portion of rack management (e.g., server, power and environment management) has its own passwords and security settings. One embodiment of the present invention provides centralized security back to the network&#39;s Active Directory (AD). The AD determines what access level a user has to manage particular devices within a data center, a rack or even a component within the device. This centralized security system eliminates the need for separate security schemes for each portion of the system (e.g., server, power and environment management). Such centralized security leverages the use of a data center&#39;s existing security control server, sometimes also called security domain controller. In other embodiment of the invention when the centralized security server is not available, the Control Module hosts its own security authentication for access to the server management. 
     Yet another feature of the invention provides for other components that extend the capabilities of the rack management system. 
     For instance, one embodiment of the invention may include a top-level application that manages multiple rack units. Such system may operate on an embedded Microsoft Windows™ operating system. The top-level application may gather and provide performance metrics and scripts to be managed and distributed to the devices throughout the attached rack. 
     Another aspect of the invention provides a distributed patch panel in which a 40 U bracket attaches to the vertical column and terminates up to three RJ45 jacks/ports per rack U allowing for the integration of distributed data patch cables. The top of the vertical column may terminate at a switch or other network device located in the top of the rack. 
     According to another embodiment of the invention, a vertical cable management tray can be added to the system in place of the distributed patch panel. This enables the organized vertical routing of any additional cables not directly handled by the invention. 
     Another embodiment of the invention provides high-density power distribution units (PDUs) in order to distribute the power evenly throughout the rack unit and minimize power cabling. Each Power Distribution Unit attaches to the Control Module through one or more serial ports. The Control Module can then control the Power Distribution and/or read its metering statistics. As an option the Power Distribution Unit will have the ability to recycle power on a per port basis via the RS-232 ports of the Control Unit. 
     Another aspect of the invention provides for power metering of total current draw. This data in combination with the server&#39;s utilization statistics may be used to determine where power costs can be reduced in a data center. 
     Another feature of the scalable rack cabinet is that the Vertical Column can be scaled to 14 U columns, 28 U columns, or more as needed. This is accomplished by providing modules (e.g., Backplane Modules, Server Interface Modules, etc.) that can be added to the Vertical Column as necessary. The system management software may be configured to permit the use of a different number of modules along the system. 
     The management software may also be configured to gather data sets, allowing for an overall map of a data center to be created. This allows for analysis of open rack areas and finding servers through the use of various metrics. The data may be mapped into a system mapping software package in order to provide elevation charts of the installation. 
     The rack architecture provides the hardware baseline to allow servers to become generic processing units. Servers are typically deployed with specific tasks, such as web serving or database functions. If access to a server is low, the server continues to run in a static state consuming power and generating heat. This methodology has led to processor utilization figures that are in the single digits for most all data centers. The increased need for computing has led to increased density, which in turn has presented the issue of providing sufficient cooling and power to the servers in a data center. The idea of using fewer computers more wisely has not been practical since there was not an efficient way of monitoring processing loads and controlling a plurality of servers. 
     According to one embodiment of the present invention, the centralized control of servers within a server rack combined with a robust software platform permits managing a pool of storage devices, networking devices and servers. This centralized management tool allows an operator to run a data center based on a predetermined best practices methodology or tweak the utilization thresholds to meet the requirements of a more customized installation. For example, if a mail server was operating at five percent (5%) capacity between the hours of nine (9) PM to six (6) AM the management system may direct that activity to another server and sequentially power down the underutilized or stagnant server. When capacity is required, the system may be brought up and made available to share the load. This eliminates wasted energy in both cooling and powering of the equipment. Additionally, such intelligent system management eliminates the need for expensive load balancing systems since the feedback loop has been migrated to the device manager as opposed to the network exclusively. The “feedback loop” refers to the intelligent sampling and the application of the appropriate corrective action. If this feedback is handled on the network exclusively, decisions are made based solely on network traffic and network transaction data. Such network-based decisions ignore important factors such as the operating environment, power consumption, and processor utilization. 
     With the ability to collect data such as processor speed, memory capacity, port capacity and hard drive capacity etc. the system can build a record of the complete rack environment based on the data gathered and applying rules programmed into the Single Board Computer  124 . This allows a server rack system to provision itself of the equipment therein (e.g., servers, storage, etc.) based on simple commands provided by the operator and build a stable and secure software environment with minimal human intervention. 
     In one implementation of the invention, by maintaining configuration and provisioning information about resources in a server rack and/or data center, an operator can actively control the migration of programs, data or responsibilities of the equipment, thus making hardware upgrades significantly simpler. 
     According to one implementation of the invention, a metering feature of the management system provides constant data gathering and analysis in order to predict failures of components or systems. Upon an alert, a human operator can be notified and/or measures can be automatically taken based on the rules programmed into the Single Board Computer  124 . This data can be used to judge the relative useful life remaining on components or provide a financial analysis on the benefits of upgrading to more current technology. In essence, metering analysis takes the guesswork out of information technology infrastructure capacity planning. 
     Since the management system is capable of gathering physical location and contents/configuration of each attached device, it can be instrumental in asset management. A top level program can gather desired elements of data from each server rack within a data center or company and provide a detailed inventory on assets and physical locations. This information is also useful in planning optimal deployment areas within a data center. 
     According to one implementation of the invention, the management system may also be employed in network load generation. Typically, if a server has become saturated the network will continue to broadcast and route packets to a particular resource (e.g., server). However, according to one implementation of the invention, a resource (e.g., server) reports back to the centralized management system that it has reached a threshold level of utilization, e.g., 85% capacity. The management system may then send a command to a router to scale back the broadcasting or shift the resource to a different device. This helps reduce networking traffic and maximizes total system performance. The centralized management architecture permits using available hardware for load shifting by providing a communication and reporting loop to monitor loads and usage metrics. 
     Another feature of the invention provides for centralizing the management of the devices within a rack cabinet (e.g., server, network equipment, power and environmental equipment, etc.). According to one implementation of the invention, each rack cabinet is associated with a particular identifier. For instance, the control module in a rack cabinet may be associated with a unique Internet Protocol (IP) address within a data center. This IP address permits identifying the location of a device within a data center. Additionally, an operator can remotely access a device over a network by using the IP address of the rack cabinet in which the device resides and accessing the device list for that rack cabinet. This IP address provides access to both IP based third party products as well as serial based third party products. In essence the IP address is a gateway to all management devices within the rack cabinet. 
     While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications are possible. Those skilled, in the art will appreciate that various adaptations and modifications of the just described preferred embodiment can be configured without departing from the scope and spirit of the invention. Additionally, it is possible to implement embodiments of the invention or some of their features in hardware, programmable devices, firmware, software or a combination thereof. The invention or parts of the invention may also be embodied in a processor-readable storage medium or machine-readable medium such as a magnetic (e.g., hard drive, floppy drive), optical (e.g., compact disk, digital versatile disk, etc), or semiconductor storage medium (volatile and non-volatile). Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.