Patent Publication Number: US-2010110628-A1

Title: Apparatus and Method for Enhancing the Maintainability and Cooling of Computer Components on Trays in a Cabinet

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/109,818, filed Oct. 30, 2008, entitled “Apparatus and Method for Enhancing the Maintainability and Cooling of Computer Components on Trays in a Cabinet,” the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the manner in which computer components are designed, configured, and installed in a given area. More particularly, this invention relates to enhancing the maintainability and cooling of computer components mounted on trays in a cabinet. 
     BACKGROUND OF THE INVENTION 
     As information technology has rapidly progressed, computer network centers such as server farms and server clusters have become increasingly important to our society. The server farms provide efficient data processing, storage, and distribution capability that supports a worldwide information infrastructure, which has come to alter how we live and how we conduct our day to day business. 
     At a site where numerous computers are connected to a network, the computers and related equipment arc often stacked in racks. Many of the racks are filled with cumbersome computers mounted on sliders, which are attached through mounting holes provided in the front and back of the rack. Each of these computers is often also housed in a chassis. It can be inconvenient to service and/or upgrade components of these computers because a computer may need to be dismounted from a rack, and a portion of the chassis housing the computer may need to be disassembled. In addition, to service and/or upgrade a component of these computers, the entire computer may need to be taken out of service. 
     Moreover, the form factor of computers is becoming progressively smaller. For example, for computer chassis with a 1U height (1.75″), approximately 1U-sized fans are typically installed inside the chassis. As compared to larger fans typically used in chassis housing computers with larger form factors, these small fans may be mechanically unreliable and may also have significantly less air moving ability, which may impact both the maintainability and cooling of computers with a small form factor. 
     In view of the foregoing problems, it would be desirable to provide techniques for enhancing the maintainability and cooling of computer components mounted on trays in a cabinet. 
     SUMMARY OF THE INVENTION 
     In one innovative aspect, the invention relates to a computer system comprising a cabinet, a first port mounted on a rear panel of the cabinet, and a tray having a plurality of computer components mounted thereon. The tray is mounted in the cabinet such that a front panel of the tray faces outward from a front side of the cabinet opposite the rear panel of the cabinet. The computer system further includes a second port mounted on the front panel of the tray, and a first cable that electrically couples the first port and the second port. The first cable is routed within the cabinet and protrudes from the front side of the cabinet. The first port also remains coupled to the second port as the tray slides outwards from the front side of the cabinet so that the plurality of computer components substantially protrude from the front side of the cabinet. The first port and the second port are for at least one of electrical power and network connectivity. 
     In another innovative aspect, the invention relates to a method of servicing a computer system including a tray having a plurality of computer components including a computer component needing attention mounted thereon. The method includes sliding the tray outward from a front side of a cabinet so that the plurality of computer components substantially protrude from the front side of the cabinet, where a first cable extends from the cabinet to a first port mounted on a front panel of the tray to provide at least one of electrical power and network connectivity to the tray. The method further includes servicing the computer component needing attention and sliding the tray inward so that the plurality of computer components no longer protrudes from the front side of the cabinet. The method is performed while the plurality of computer components remain in service. 
     In a further innovative aspect, the invention relates to a method of upgrading a computer system including a tray having a plurality of computer components. The method includes sliding the tray outward from a front side of a cabinet so that the plurality of computer components substantially protrude from the front side of the cabinet, where a first cable extends from the cabinet to a first port mounted on a front panel of the tray to provide at least one of electrical power and network connectivity to the tray. The method further includes mounting a first computer component on the tray. The method further includes checking that the first computer component is operational, including checking that the first computer component has at least one of electrical power and network connectivity. The method further includes sliding the tray inward so that the first computer component and the plurality of computer components no longer protrude from the front side of the cabinet. The method is performed while the plurality of computer components remain in service. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a front perspective view of a computer system including a cabinet and trays mounted in the cabinet, in accordance with one embodiment of the present invention; 
         FIG. 2  illustrates a top perspective view of a tray including computer components mounted thereon, in accordance with one embodiment of the present invention; 
         FIG. 3  illustrates a rear perspective view of a computer system including a cabinet, and including fans and ports mounted on a rear panel of the cabinet, in accordance with one embodiment of the present invention; 
         FIG. 4  illustrates a front perspective view of a computer system including a cabinet and trays mounted in the cabinet, where cables extend from the cabinet to ports mounted on a front panel of the tray, in accordance with one embodiment of the present invention; 
         FIG. 5  illustrates a front perspective view of a computer system including a cabinet and a tray substantially protruding from the front side of the cabinet, where cables extend from the cabinet to ports mounted on a front panel of the tray, in accordance with one embodiment of the present invention; 
         FIG. 6  illustrates a phantom front perspective view of a tray mounted to a frame with a strip that latches the tray in the frame, in accordance with one embodiment of the present invention; 
         FIG. 7  illustrates a phantom side perspective view of the structure of  FIG. 6 ; and 
         FIG. 8  illustrates a logical block diagram of power connections and network connections to trays in a cabinet, in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a front perspective view of a computer system  100  including a cabinet  110  and trays  105  mounted in the cabinet  110 , in accordance with one embodiment of the present invention. The cabinet  110  has a top panel  101 , side panels  102 , and a bottom panel  103 . Trays  105  have front panels  106  that face outward from a front side  104  of the cabinet  110 . The front side  104  of the cabinet  110  may at least partially expose front panels  106  of trays  105 . In one embodiment, the front side  104  of the cabinet  110  may not be covered with a front panel to facilitate access to the trays  105 , such as for servicing or replacement of the trays  105 . The exposure of the front panels  106  also enhances airflow from outside the cabinet  110  toward the front panels  106  of the trays  105 , or the reverse, for cooling computer components mounted on the trays  105 . Alternatively, the front side  104  of the cabinet  110  may be covered with a front panel (not shown). The front panel may be used to reduce electromagnetic interference (EMI) from the cabinet  110 . The front panel may also allow air to flow from outside the cabinet  110  through the front panel toward the front panels  106  of the trays  105 , or the reverse. Computer components may be mounted on the trays  105 . The trays  105  may be horizontally mounted in the cabinet  110 , as shown in  FIG. 1 . Alternatively, the trays  105  may be vertically mounted in the cabinet  110 . If vertically mounted, the trays  105  may be mounted in one or more vertically spaced apart bays (not shown). The trays  105  may be mounted on rails attached to side panel  102  such that the rails face trays  105  mounted in the cabinet  110 , to allow the trays  105  to slide in and out of the cabinet  110 . 
     In one embodiment, the cabinet  110  may have a height that is an integer multiple of 1U. Some examples of commonly used cabinet heights are 22U, 36U, 40U, 42U, and 44U. Each tray  105  may also have a height that is an integer multiple of 1U, such as 1U or 2U. Alternatively, each tray  105  may have a height that is not an integer multiple of 1U, such as 0.5U or 1.5U. The cabinet  110  may also have a height that is not an integer multiple of 1U, such as 43.5U or 44.5U. In one representative embodiment, the cabinet  110  may have a width of approximately 26″ and a depth of approximately 40″. Trays  105  horizontally mounted in the cabinet  110  may correspondingly have a width of approximately 19″ and a depth of approximately 31″. 
     Trays  105  for each type of cabinet  110  may be of a single uniform height, so that the spacing of trays  105  in each type of cabinet  110  is uniform. This has the operational advantage of enabling trays  105  for each type of cabinet  110  to be easily interchangeable. Alternatively, trays  105  of different types may be of different heights. For example, a first type of tray  105  that supports expansion cards may be of a greater height than a second type of tray  105  that does not support expansion cards. 
     There are various advantages of mounting computer components on trays  105  mounted in the cabinet  110 , as compared to housing computer components in a chassis mounted in a rack. Some of the advantages are described here, while other advantages are described later in this description. The design of a tray may he simpler than that of a chassis, so new tray designs supporting new groupings and placement of computer components may be generated more quickly than corresponding new chassis designs. The fabrication of a tray may also be cheaper than the fabrication of a chassis because a tray may have a simpler structure and may require less material than a chassis. Moreover, EMI testing may be simplified for trays mounted in a cabinet because EMI testing may only need to be done per cabinet, rather than per chassis. 
     In addition, the computer components mounted on trays  105  may be exposed so that the computer components are easily accessible after sliding a tray  105  out of the cabinet  110 . In contrast, a chassis housing may cover computer components mounted in the chassis. Because a tray does not require the additional structure covering the computer components mounted on the tray, it may therefore be possible to pack trays more closely together than would otherwise be possible using chassis. 
       FIG. 2  illustrates a top perspective view of the tray  105  including computer components mounted thereon, in accordance with one embodiment of the present invention. The tray  105  has a front panel  106  and side panels  200 . The front panel  106  includes one or more types of ports. The front panel  106  may include one or more ports  202  for electrical power. The front panel  106  may also include one or more ports  204  for network connectivity, such as Ethernet ports. In addition, the front panel  106  may include other ports that may be accessed as part of servicing or upgrading the trays  105 . It is desirable for the front panel  106  to include all ports that should remain connected as the tray  105  is slid out of the cabinet  110  to facilitate servicing and/or upgrading one or more components on the tray  105  while the other components on the tray  105  remain in service, as described in more detail in the description of  FIG. 5 . The front panel  106  may also include perforations  206  that allow airflow through the front panel  106 . 
     In one embodiment, the tray  105  has mounted thereon computer components including one or more printed circuit boards (PCB)  220 , one or more hard disks  232 , and one or more power supplies  230 . The configuration of the tray  105  is flexible, and other types of computer components may also be mounted on the tray  105 . For example, the tray  105  may be configured as a computer server, a storage node, and/or a switch. Each PCB  220  may have mounted thereon one or more processors  221 , memory  222 , and a plurality of I/O connectors. Each PCB  220  also may have mounted thereon other types of electronic components, such as application specific integrated circuits (ASICs). The types of I/O connectors may vary depending on the configuration of the PCB  220 , but may include, for example, one or more network connectors  224  (such as female RJ-45 connectors), one or more USB ports  226 , and one or more video ports  228  (such as DVI connectors). The I/O connectors may further include, for example, an AT connector, a PS/2 connector, a SCSI port, an ATA port, a serial port, an IEEE 1394 port, and a parallel port. 
     The tray  105  may include an opening  210  in each side panel  200 , and an opening  211  on each side of the front panel  106 . A strip  212  is mounted on each side panel  200  using, for example, one or more screws  218 . Each strip  212  faces inward toward the computer components mounted on the tray  105 . Each strip  212  may be a thin piece of metal with a protrusion  214  extending from a first side of each strip  212 . Each strip  212  is mounted so the protrusion  214  extends through the opening  210  in the side panel  200 . Each strip  212  includes a tab  216  that protrudes from the opening  211  in the front panel  106 . The strips  212  are configured to serve as part of a latching mechanism to hold each tray  105  in place in the cabinet  110 , so the tray  105  does not slide in and out of the cabinet  110  without human intervention. The latching mechanism is described further in  FIGS. 6 and 7 . 
       FIG. 3  illustrates a rear perspective view of the computer system  100  including the cabinet  110 , and including fans  302  and ports  304  and  306  mounted on a rear panel  300  of the cabinet  110 , in accordance with one embodiment of the present invention. The rear panel  300  may include one or more ports  304  for electrical power. The rear panel  300  may also include one or more ports  306  for network connectivity, such as Ethernet ports. 
     In one embodiment, air can be drawn out of the cabinet  110  by the fans  302 . This creates a negative pressure region in the cabinet  110 , such as between the trays  105 , so that air travels from the environment, through the perforations  206  on the front panels  106  of the trays  105 , and into the cabinet  110 . In this embodiment, components on the trays  105  can be placed so, for example, components that generate the most heat are placed near the rear panel  300  on which the fans  302  are mounted. Alternatively, fans  302  can push air from the environment into the cabinet  110 , and out of the cabinet  110  through the perforations  206  on the front panels  106  of the trays  105 . In this embodiment, components on the trays  105  can be placed so, for example, components that generate the most heat are placed near the front panels  106 . 
     The fans  302  are preferably at least 4U in diameter, and can eliminate the need for fans mounted on the trays  105  or in computer components mounted on the trays  105 , such as power supplies  230 . The increase in the size of the fans  302  as compared to the approximately 1U-diameter fans typically mounted on trays with 1U height significantly increases airflow between the trays  105  mounted in the cabinet  110 , which may reduce the probability of failure of the computer components mounted on the trays  105  due to overheating. Larger fans  302  may also be more mechanically reliable than 1U fans. In addition, the placement of the fans  302  on the rear panel  300  of the cabinet  110  makes them easily replaceable in the event of a failure of one of the fans  302 . 
     In one embodiment, the fans  302  may run at partial speed, such as 50% speed, in regular operating mode. The speed of one or more of the fans  302  may be adjusted up or down based on measurements such as temperature and/or air flow measurements at one or more locations in the cabinet  110 . The failure of a fan  302 A may be detected by a mechanism such as temperature and/or air flow measurements at one or more locations in the cabinet  110 . In the event of such a failure, the speed of the fans  302  excluding the failed fan  302 A may be adjusted up. The amount of this upward adjustment may be preconfigured and/or based on measurements such as temperature and/or air flow measurements at one or more locations in the cabinet  110 . The amount of this upward adjustment may be constrained by the maximum operating speed of the fans  302 . The higher speed is maintained until the failed fan  302 A is replaced. 
     Cabinets  110  may be deployed in rows such that the rear panels  300  of the cabinets  110  face each other. This may create warm aisles between the rear panels  300  of the cabinets  110  if cooling air is exhausted from the rear panels  300 , or alternatively may create warm aisles between the front sides  104  of the cabinets  110  if cooling air is exhausted from the front panels  106  of the trays  105 . Alternatively, cabinets  110  may be deployed in a container with rear panels  300  facing interior walls of the container so that cooling air is exhausted into an exhaust region between the rear panels  300  and the interior walls of the container, as described in U.S. Ser. No. 11/860,685, to Coglitore et al., filed on Sep. 25, 2007, incorporated by reference herein in its entirety. The heated air may be cooled by any of a variety of known cooling systems for removing heat from air, certain embodiments of which are described in U.S. Ser. No. 11/860,685. 
       FIG. 4  illustrates a front perspective view of a computer system  100  including the cabinet  110  and trays  105  mounted in the cabinet  110 , where cables  404  and  406  extend from the cabinet  110  to ports  202  and  204  mounted on the front panel  106  of each tray  105 , in accordance with one embodiment of the present invention. Each cable  404  may electrically couple port  304  on the rear panel  300  to port  202  on the front panel  106  of the tray  105 , so as to provide electrical power to port  202 . Each cable  406  may also electrically couple port  306  on the rear panel  300  to port  204  on the front panel  106  of the tray  105 , so as to provide network connectivity to port  204 . The cables  404  and  406  may protrude from the front side  104  of the cabinet  110 , and may be routed within the cabinet  110 . 
     The cabinet  110  may include a frame  400  on which each tray  105  is mounted such that the front panel  106  of the tray  105  faces outward from a front panel  402  of the frame  400 . The trays  105  may be mounted on rails attached to the frame  400  to allow the trays  105  to slide in and out of the cabinet  110 . The front panel  402  of the frame  400  may include one or more openings  408 . Each opening  408  may be positioned adjacent to one of the trays  105 . In addition, a tray  105 A may have one opening  408 A adjacent to a first side of the tray  105 A, and another opening  408 B adjacent to a second side of the tray  105 A opposite the first side. In one embodiment, the one or more cables  404  to be connected to the tray  105 A may be routed through the opening  408 A, and the one or more cables  406  to be connected to the tray  105 A may be routed through the opening  408 B. 
       FIG. 5  illustrates a front perspective view of the computer system  100  including the cabinet  110  and the tray  105  substantially protruding from the front side  104  of the cabinet  110 , where the cables  404  and  406  extend from the cabinet  110  to the ports  202  and  204  mounted on the front panel  106  of the tray  105 , in accordance with one embodiment of the present invention. The ports  202  and  204  remain coupled to ports  304  and  306 , respectively, on the rear panel  300  as the tray  105  slides outwards from the front side  104  of the cabinet  110 , so that computer components on the tray  105  can be accessed from the front side  104  of the cabinet  110 . In one embodiment, the cabinet  110  includes service loops for cables  404  and  406  that include an extra length of cable. As the tray  105  slides outwards from the front side  104  of the cabinet  110 , the extra lengths of cables  404  and  406  can be unwound so that cables  404  and  406  remain coupled to the ports  202  and  204 , respectively. A spring loaded system may be provided to facilitate the retraction of the extra lengths of cables  404  and  406  as the tray slides back into the cabinet  110 . Alternatively, the extra lengths of cables  404  and  406  may retract as a result of the motion of tray  105  sliding back into the cabinet  110 , in combination with gravity. The extra lengths of cables  404  and  406  may also be manually fed back into the service loops. The cables  404  and  406  can be disengaged from the ports  202  and  204 , respectively, to enable the tray  105  to be fully removed from the cabinet  110 . 
     In one embodiment, cables  500  may extend from ports  202  and/or  204  to a port mounted on one or more of the computer components mounted on the tray  105 . For example, cables  500  can plug into network connectors  224  of the motherboard  220 . Alternatively, power may be distributed over rails (not shown) to the computer components on the tray  105 . If a tray  105  is upgraded by mounting an additional computer component on the tray  105 , one or more cables  500  may be plugged into connectors on the additional component as part of the upgrade process. 
     There are various operational and maintainability advantages of the cabling configuration shown in  FIGS. 4 and 5  as applied to trays  105  mounted in the cabinet  110 . To service or upgrade computer components on a tray, the components can be accessed by simply sliding the tray out of the cabinet. In contrast, in a conventional rack-based system, more effort is typically required, as a computer chassis including the computer components typically needs to be unscrewed from the rack frame or from sliders attached to the rack frame. Then, the lid of the computer chassis typically needs to be unscrewed from the chassis frame to access the computer components in the chassis. 
     In addition, the cabling configuration shown in  FIGS. 4 and 5  as applied to trays  105  mounted in the cabinet  110  enables servicing and/or upgrade of components on a tray  105  while other unaffected components on the tray  105  remain in service. In the embodiment of  FIG. 5 , the front panel  106  includes port  202  for power connectivity and ports  204  for network connectivity. An outside power source is connected to port  304 , and a data connection for the cabinet  110  is connected to port  306 . External connections to ports  304  and  306  are not typically disturbed as part of servicing and/or upgrading trays  105 . Since cables  404  and  406  can extend and thus can remain connected to ports  202  and  204  as the tray  105  is slid out of the cabinet  110 , the tray  105  can remain electrically coupled to ports  304  and  306 . Thus, the tray  105  can maintain power and network connectivity as it is slid out of the cabinet  110 , and thus computer components on the tray  105  can remain in service. If additional types of connections are needed for components on the tray  105  to remain in service, this cabling approach can be used so that the tray  105  can also maintain the additional types of connectivity as the tray  105  is slid out of the cabinet  110 . 
     The cabling configuration shown in  FIGS. 4 and 5  as applied to trays  105  mounted in the cabinet  110  also enables flexible and convenient servicing and/or upgrade of computer components on the trays  105 . Since cabling needed as part of this servicing and/or upgrade is accessible from the front side  104  of the cabinet  110 , there is no need, for example, to access the rear of the cabinet  110  or to remove the rear panel  300  of the cabinet  110  to access cables in the rear of the cabinet  110 . This can avoid taking one or more fans  302  on the rear panel  300  out of operation, which is important to maintain an acceptable operating temperature for trays  105  in embodiments in which separate fans are not provided for cooling the trays  105 . If servicing or upgrade requires power to be shut off for a particular tray  105 A, this can easily be done from the front side  104  of the cabinet  110 , without affecting the operation of the other trays  105 . Similarly, network connectivity can be removed and restored for a portion of a tray  105 A without affecting other portions of the tray  105 A or other trays  105 . 
     As part of servicing or upgrade, it may be desirable to check that a computer component is operational prior to sliding a tray  105  back into the cabinet  110 . This checking may be done using any of the many well-known techniques for testing computer components, such as testing whether electrical inputs and outputs of the components are in valid ranges, or whether electrical outputs of the components assume expected values for particular electrical input values. 
       FIG. 6  illustrates a front perspective view of the tray  105  with the frame  400  on which the tray  105  is mounted rendered transparently to show the strip  212  that latches the tray  105  in the frame  400 , in accordance with one embodiment of the present invention. To latch the tray  105  in the frame  400 , the protrusion  214  in the strip  212  extends through an opening  602  in a side panel  600  of the frame  400  as the tray  105  is pushed back into the cabinet  110 . To unlatch the tray  105  from the frame  400 , the tabs  216  on one or both sides of the front panel  106  of the tray  105  may be pushed in a direction pointing away from the side panel  602 . By pushing the tabs  216 , the protrusions  214  of the strips  212  are withdrawn from the openings  602 , enabling the tray  105  to be pulled out of the cabinet  110 . 
       FIG. 7  illustrates a side perspective view of the tray  105  with the frame  400  on which the tray  105  is mounted rendered transparently to show the strip  212  that latches the tray  105  in the frame  400 , in accordance with one embodiment of the present invention. 
       FIG. 8  illustrates a logical block diagram of power connections  404  and network connections  406  to trays  105  in the cabinet  110 , in accordance with one embodiment of the present invention. In this embodiment, one or more external power sources is connected to ports  304 . The external power sources may, for example, be 110V/220V AC sources or 48V DC sources. A power distribution unit (PDU)  802  distributes the input electrical power to one or more trays  105  via cables  404  that extend from the PDU  802  to ports  202  on the trays  105 . The power supply  230  on each tray  105  may be a rectifier that converts an AC input to a DC output. In addition, network connectivity is provided to an uplink port  306  of a switch  800 . The switch  800  provides network connectivity to the trays  105  via cables  406  that extend from the switch  800  to ports  204  on the trays  105 . 
     The figures provided are merely representational and may not be drawn to scale. Certain proportions thereof may be exaggerated, while others may be minimized. The figures are intended to illustrate various implementations of the invention that can be understood and appropriately carried out by those of ordinary skill in the art. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required in order to practice the invention. Thus, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed; obviously, many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, they thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the following claims and their equivalents define the scope of the invention.