Abstract:
In some examples, a chassis contains a fabric module and a plurality node modules that are arranged in a plurality of rows. The fabric module is positioned in a space between a first row and a second row of the plurality of rows, and the fabric module is connected to at least two node modules of the plurality of node modules to provide communications connectivity between the at least two node modules, the chassis to accept longitudinal insertion in a longitudinal direction of the plurality of node modules and the fabric module, the fabric module being removable in the longitudinal direction from the chassis by moving the fabric module in the space between the first row and the second row without first removing the node modules in the plurality of rows.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of U.S. application Ser. No. 13/808,507, filed Jan. 4, 2013, which is a national stage application under 35 U.S.C. §371 of PCT/US2010/048970, filed Sep. 15, 2010, both hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    A typical blade system includes a chassis for holding several “blades”. Each blade can include one or more processor nodes, each of which includes one or more processors and associated memory. The chassis can include a backplane that provides power and connectivity, input/output (I/O) connectivity including network connectivity and inter-blade connectivity. In some blade systems, front connector bars spanning two or more blades provide or supplement inter-blade connectivity. In some blade systems, the inter-blade connectivity provides for cache coherent operation among processor blades associated with different blades. This allows a set of blades to operate as a single more powerful computer rather than as a network of separate computers that happen to be in the same chassis. Blade systems can be upgraded conveniently by swapping previous-generation blades with more capable newer-generation blades. In this sense, blade systems provide a hedge against obsolescence and allow a customer&#39;s investment to be amortized over a longer time, decreasing the overall cost of ownership. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a schematic diagram of a modular computer system in accordance with an embodiment. 
           [0004]      FIG. 2  is a schematic diagram of a fabric module of the computer system of  FIG. 1 . 
           [0005]      FIG. 3  is a flow chart of a process implementable in the computer system of  FIG. 1 . 
           [0006]      FIG. 4  is a flow diagram for a module swap operation and showing front and side views of a blade computer system in accordance with an embodiment. 
           [0007]      FIG. 5  is a front schematic view of a chassis of the computer system of  FIG. 4 . 
           [0008]      FIG. 6  is a schematic view of a blade of the computer system of  FIG. 4 . 
           [0009]      FIG. 7  is a schematic view of a fabric module of the computer system of  FIG. 4 . 
           [0010]      FIG. 8  is a schematic view of a fabric module of the computer system of  FIG. 4 . 
           [0011]      FIG. 9  is a schematic view of a fabric module of the computer system of  FIG. 4 . 
           [0012]      FIG. 10  is a flow chart of a process implementable in the system of  FIG. 4 . 
           [0013]      FIG. 11  is a schematic diagram for a fabric module installable in the system of  FIG. 4 . 
           [0014]      FIG. 12  is a schematic diagram for a fabric module installable in the system of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    A modular computer system  100 , shown in  FIG. 1 , includes a chassis  101 , node modules N 1  and N 2 , and a fabric module  107  that provides routing  109  over which node modules N 1  and N 2  communicate with each other. To this end, fabric module  107  includes connectors C 1  and C 2  on its top face  109  for connecting to respective node modules, e.g., node modules N 1  and N 2 , as shown in  FIG. 2 . Fabric module  107  can be inserted or removed at a process segment  301 , in the same longitudinal dimension (into or out of the page given the front view of  FIG. 1 .) that node modules N 1  and N 2  can be removed. Node modules N 1  and N 2  can be run cooperatively, e.g., as a single computer, with fabric module  107  installed at a process segment  302  (which can occur before a removal or after an insertion of process segment  301 ). 
         [0016]    Herein, “module” refers to a hardware entity that can be inserted into a chassis. The terms “node module” and “fabric module” are defined relative to each other so that a “fabric module” is a module configured to provide communications connectivity between or among node modules. The node modules can include general-purpose or application-specific computer modules (providing processing, storage, and communications, e.g., I/O and networking”, modules that emphasize one data handling function, e.g., storage modules, connectivity modules (e.g., network switches dedicated to one or more network layers), application-specific hardware (e.g., sensors and controllers). A “processor module” is a computer module including one or more processor nodes (each of which can include one or more processors and memory). “Blade” herein, refers to a type of node module having a physically “thin” configuration. 
         [0017]    Unlike systems in which connectivity is provided by a backplane or a midplane, system  100  permits connectivity to be upgraded without replacing an entire chassis. Fabrics typically can accommodate a small number of computer (e.g., processor) upgrades, but eventually are outstripped by the capabilities of the newer computers. Using replaceable fabric modules allows the chassis to be retained, e.g., for a decade or more rather than for just a few years, through more generations of upgrades. Furthermore, fabric module  107  does not impede front-to-back airflow. Relative to systems that provide inter-blade connectivity using front connector bars, serviceability is improved as fabric module  107  does not have to be removed to replace a connected node module. 
         [0018]    A blade system  400  includes a chassis  401 , a vertically adjacent pair of rows of blades (node modules) B 10  and B 20 , and fabric modules FM 1 , FM 2 , and FM 3 , as shown in  FIG. 4 . Row B 10  includes blades B 11 , B 12 , B 13 , and B 14 . Row B 20  includes blades B 21 , B 22 , B 23 , and B 24 . Other embodiments provide for different numbers of rows and different numbers of blades per row. Also, alternative embodiments provide for different numbers of fabric modules for a given number of blade rows. For example, top and bottom fabric modules, such as FM 1  and FM 3  in  FIG. 4 , can be omitted. 
         [0019]    As shown in the bottom half of  FIG. 4  for blade B 24  and fabric module FM 2 , blades B 11 -B 14 , blades B 21 -B 24 , and fabric modules FM 1 -FM 3  are all removable and insertable through the front  403  of chassis  401  using longitudinal motions. Herein, a horizontal-vertical-longitudinal coordinate system is used. “Horizontal” is the dimension in which the blades of a row are spaced; for example, blades B 11 -B 14  are arranged left to right along the horizontal dimension. “Vertical” is the dimension in which a fabric module is spaced from a row of blades connected to it; for example, fabric module FM 1 , row B 10 , fabric module FM 2 , row B 20 , and fabric module FM 3  are arranged bottom to top along the vertical dimension. “Longitudinal” refers to the dimension of insertion for modules. In the illustrated embodiment, these dimensions are substantially orthogonal to each other, in other words, each pair of dimensions defines an acute or right angle more than 45° so that they are more orthogonal than aligned. Herein, terms such as “front”, “rear”, “top”, “bottom”, “left”, “right” “above”, and “below” are to be interpreted in the context of the coordinate system. 
         [0020]    Chassis  401 , shown separately in  FIG. 5 , provides blade (node module) slots  501  and fabric-module slots  503  for receiving, guiding, and securing blades and fabric modules. In some embodiments, other node modules, e.g., network modules, can be installed in the vertical blade slots, with computer-network linkages through fabric modules. In addition, chassis  401  provides power connections  505  for all modules (including blades) and data connections e.g., with peripherals and networks for all blades. Other embodiments include cam and clamping mechanisms for securing modules and for effecting connections between blades and fabric modules. Also, in some embodiments, chasses include integrated cooling, e.g., fans or liquid cooling features. Also, in some embodiments, management features are provided, e.g., virtual ports. 
         [0021]    Blades B 12 -B 14  and B 21 -B 24  are similar to B 11 , described with reference to  FIG. 6 . Blade B 11  is a processor module including two processor nodes P 1  and P 2 . In alternative embodiments, blades can include one processor node or more than two processor nodes; different blades can have different numbers of processors and amounts of memory per node. Processor node N 1  includes four processors CP 1 , memory (RAM) ME 1 , and storage (ST 1 ). Processor node N 2  includes four processors CP 2 , memory (RAM) ME 2 , and storage (ST 2 ). Processor nodes P 1  and P 2  are coupled so that they can operate coherently—i.e., as though memories ME 1  and ME 2  constituted a unified memory that can be addressed directly by any processor of nodes N 1  and N 2 . 
         [0022]    Blade B 11  includes a top connector  611  and a bottom connector  613  for connecting to vertically adjacent fabric modules, e.g., modules FM 2  and FM 1 , respectively in  FIG. 4 . Each blade can be configured so that zero, one, or both of its top and bottom connectors are active. Blade B 11  also includes on its rear face  635  power and network connectors  621  and  623 , respectively, for receiving power and establishing specialized connectivity, e.g., such as for management. Connectors  621  and  623  are on the top  631  and bottom  633  of blade B 11  respectively, more toward the rear face  635  of blade B 11  than its front face  637 . 
         [0023]    Various embodiments employ different techniques to achieve connectivity with communication signals: (a) card edge connector, where the card edge of the blade module slides between two adjacent connectors, (b) cam down or up actuation, where the blade slides in and is pressed down against a traditional connector on the shelf via a cam action, (c) flex-cable connector, where the blade slides in and the connector&#39;s flex cable extension is pressed down or up against a shelf using a cam action, and (d) optically interconnected systems where the shelf contains optical “traces” (e.g., waveguides) and the connection may be made with a slide-by, self-aligning set of optical connectors. 
         [0024]    Fabric module FM 2  is represented in  FIG. 7 . Routing glue logic  701  provides a switched star topology for full 8×8 routing. (Connectors shown using dashed lines are on the bottom of fabric module FM 2 ). A particular routing can be selected via a front panel of fabric module FM 2  or by a management station connected to blade system  400 . In addition to routing, routing glue logic  701  provides other glue functions such as signal buffering and snoop filtering. 
         [0025]    Fabric module FM 1  is represented in  FIG. 8 . It is adapted to couple the two rightmost blades and the two leftmost blades in a row. Fabric module FM 3  is depicted in  FIG. 9 . It is adapted to connect four blades in a row. In an alternative embodiment, a fabric module has the pattern and connectors shown in  FIG. 8  on its top face and the pattern and connectors of  FIG. 9  on its bottom face; other alternative embodiments can have different patterns on their top and bottom faces. In some such embodiments, a connection configuration can be changed by inverting a fabric module with different patterns (and connectors) on its top and bottom faces even though the fabric module itself is not dynamically reconfigurable. 
         [0026]    In practice, computer system  400 ,  FIG. 4 , could be operated with the blades communicatively connected to fabric module FM 2  and not communicatively coupled to fabric modules FM 1  and FM 3 , e.g., at a process segment  1001  of a process  1000  flow charted in  FIG. 10 . To prepare for repairing or replacing fabric module FM 2 , process segment  1002  provides for breaking the connection between fabric module FM 2  and any blades connected to it. If it is desired to run some of these blades coherently, they can be reconnected at process segment  1003  using other fabric modules, e.g., fabric modules FM 1  and FM 3 . This may not result in the exact configuration provided by fabric module FM 2 , but may still improve upon running blades individually. 
         [0027]    Fabric module FM 2  can be removed longitudinally at process segment  1004 . The removed fabric module can be repaired, inverted, or replaced at process segment  1005 . Once repair is complete, the module inverted, or a replacement is found, the resulting fabric module can be inserted longitudinally at process segment  1006 . To effect coherent processing via connections of the newly inserted fabric modules, Communicative connections to the other fabric modules can be broken and communicative connections to the newly inserted module established at process segment  1007 . 
         [0028]    A couple of other fabric modules FM 4  and FM 5  are shown in  FIGS. 11 and 12 , respectively. Fabric module FM 4  provides four-point connections between vertical pairs of two-node blades. Thus, for example, the two processor nodes of blade B 11  and the two processor nodes of blade B 21  are grouped to form a four processor-node set that runs coherently. Fabric module FM 5  provides eight-point connections for left and right blocks of four blades. 
         [0029]    Blade system  400  provides for fabric modules of many other glued and glueless configurations. Also, communicative connections can be electrical, optical or both. Some fabric modules may provide for different connection configurations by inverting the fabric module vertically, i.e., installing it after a 180° rotation about a longitudinal axis. Some fabric modules may have fixed configurations; others may be reconfigurable while installed. Connections can be made using more than one fabric module by using both top and bottom blade connectors. Such connections can be made through the processor nodes of a blade. Also, a specially designed blade can allow a direct connection between upper and lower fabric modules. For example, blade B 21  of  FIG. 4  provides for a direct connection between fabric modules FM 2  and FM 3 . 
         [0030]    System  400  thus provides for a customer installable fabric module “shelf”; in general, this can mean that the cost for high speed blade-to-blade connectivity is only paid when it is used. Connected blades can be independently serviced or upgraded. One chassis can be enabled for a variety of configurations depending on the nature of the fabric modules installed. Also, in its horizontal orientation, a fabric module does not impede front-to-back airflow, unlike a traditional front-plane or mid-plane. Furthermore, the interconnect shelf itself can be independently serviced or upgraded. 
         [0031]    In other blade systems, blades may be swappable through the front face of a chassis while fabric modules are swappable through the rear. This configuration can allow connections between fabric and blades that are effected by abutting instead of sliding by each other. Some blade systems use one-sided patterns; to connect to blade both above and below, a pair of fabric modules can be inserted back-to-back. The back-to-back connection can provide inter-layer connections between the fabric modules and thus between rows of blades. Some blade systems use both horizontal and vertical fabric modules (and corresponding slots), defining a rectangular array of “cubbie holes”, each of which can hold multiple compute and network blades. 
         [0032]    In some embodiments, a chassis configured to hold processor modules and one or more fabric modules is unpopulated, i.e., does not presently hold any processor modules or fabric modules. In other embodiments, such a chassis is partially or completely populated by other types of modules, e.g., modules having primary purposes, e.g., data input or output or both, other than data processing or inter-module routing. “Coherently” herein applies to a multi-processor system for which multiple processors treat a common or collective memory as a unified whole having a single consistent state. “Cooperatively” means working interactively (either coherently or non-coherently) to accomplish a goal. 
         [0033]    Herein, a “system” is a set of interacting elements, wherein the elements can be, by way of example and not of limitation, mechanical components, electrical elements, atoms, the physically encoded forms of instructions encoded in storage media, and process segments. In this specification, related art is discussed for expository purposes. Related art labeled “prior art”, if any, is admitted prior art. Related art not labeled “prior art” is not admitted prior art. The illustrated and other described embodiments, as well as modifications thereto and variations thereupon are within the scope of the following claims.