Patent Publication Number: US-6993566-B2

Title: Entity self-clustering and host-entity communication such as via shared memory

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates generally to entities, such as service processors that may be found within nodes of a system, and more particularly to the self-clustering of such entities, so that, for instance, a single image of the service processors appears to the operating system of the system and/or a management console for the system. 
     2. Description of the Prior Art 
     As computer systems, such as server systems, become more complex, they have been divided into different nodes that operate as separate units. Each node may have its own processors, memory, and input/output (I/O) modules. Functionality performed by a system may be divided among its various nodes, such that each node is responsible for one or more different functions. Each node has a service processor (SP) that functions independently of the service processors of the other nodes, but which allows external access to the hardware of its node. 
     A complication to dividing a system into different nodes is that the operating system (OS) running collectively on the system, and the management consoles used to manage the system externally, have traditionally had to be aware of the specific aspects of this division into nodes. The operating system, for instance, has to know which service processor is responsible for which hardware and functionality of the system, so that messages can be routed to the appropriate service processor. Similarly, management consoles have to know the mapping of the service processors to the system&#39;s hardware and functionality. 
     This adds increased complexity to the operating system and the management consoles. Significant configuration may have to be accomplished to ensure that the operating system and the consoles are properly aware of the different service processors and the functions that have been assigned to them. Furthermore, like all system components, service processors sometimes fail. To ensure that the system itself does not fail, another service processor may have to temporarily act as the failover processor for the down processor. The operating system and the consoles must be aware of such failover procedures, too. Load balancing and other inter-service processor procedures also require knowledge of the distribution of functionality over the service processors. 
     In addition, traditional communication between an operating system and the service processors of the system occurs within the firmware of the system. Firmware is software that is stored in hardware, such that the software is retained even after no power is applied to the hardware. The use of conventional firmware, however, degrades performance significantly. For instance, firmware is not re-entrant. That is, only one processor can execute the firmware at a single time. This means that the firmware may present a bottleneck to the efficient running of the system. 
     In other contexts, the management of multiple resources is accomplished on a simplistic basis. For example, in the context of storage devices, such as hard disk drives, a redundant array of information disks (RAID) provides for limited interaction among resources. A RAID may be configured so that each hard drive redundantly stores the same information, that data is striped across the hard drives of the array for increased storage and performance, or for additional or other purposes. However, the drives themselves do not actively participate in their aggregation. Rather, a master controller is responsible for managing the drives, such that the drives themselves are not aware of one another. 
     Therefore, such solutions are not particularly apt in the system division of functionality and hardware over multiple service processors scenario that has been described. For example, having a master controller in this scenario just shifts the burden of knowing the functionality and hardware division from the management consoles and the operating systems to the controller. This does not reduce complexity, and likely does not prevent reductions in system performance. 
     Other seemingly analogous resource management approaches have similar pitfalls. Network adapters that can be aggregated to provide greater bandwidth, for instance, are typically aggregated not among themselves, but by a host operating system and/or device driver. This host operating system and/or device driver thus still takes on the complex management duties that result when multiple resources are managed as a single resource. In other words, complexity is still not reduced, and potential performance degradation is still not prevented. 
     For these described reasons, as well as other reasons, there is a need for the present invention. 
     SUMMARY OF THE INVENTION 
     The invention relates to entities, such as service processors, within a system. In a method of the invention, each entity self-discovers all the other entities, such that the entities are aggregated as a cluster. Each entity maintains an object map that represents the hardware of the system for which it is responsible as objects. A first identifier and a second identifier uniquely identify each object. The first identifier corresponds to the entity on which the object resides, whereas the second identifier distinguishes the object from other objects also residing on the entity. 
     A system of the invention includes a self-aggregated cluster of entities, and a host. The host communicates with the cluster of entities such that it need not be aware which of the entities performs a given function. An article of manufacture of the invention includes a computer-readable medium and means in the medium. The means is for an entity of a system self-discovering all the other entities of the system to aggregate the entities as a cluster. The means is further for the entity maintaining an object map representing the resources of the system for which it is responsible as objects. 
     Other features and advantages of the invention will become apparent from the following detailed description of the presently preferred embodiment of the invention, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a system according to a preferred embodiment of the invention, and is suggested for printing on the first page of the issued patent. 
         FIG. 2  is a diagram of a system including a number of service processors communicating with one another over a service processor network, in conjunction with which embodiments of the invention can be implemented. 
         FIG. 3  is a diagram of the system of  FIG. 2  with the addition of a management console, in conjunction with which embodiments of the invention can be implemented. 
         FIG. 4  is a diagram of the system of  FIG. 2  with the addition of shared memory and an operating system, in conjunction with which embodiments of the invention can be implemented. 
         FIG. 5  is a flowchart of a method showing how service processors can self-cluster with one another, according to an embodiment of the invention. 
         FIG. 6  is a diagram showing first and second identifiers of an example node. 
         FIG. 7  is a diagram showing an example object map in which first and second identifiers are stored. 
         FIG. 8  is a flowchart of a method showing how an operating system can communicate with self-clustered service processors, according to an embodiment of the invention. 
         FIG. 9  is a diagram showing an example system in which a memory shared by a number of service processors has been divided into different parts, or channels, where each service processor is responsible for a subset of these channels. 
         FIG. 10  is a flowchart of a method showing how a management console can communicate with self-clustered service processors, according to an embodiment of the invention. 
         FIG. 11  is a diagram of a system according to a more general embodiment of the invention in which a host communicates with self-clustered entities through a shared memory. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Overview 
     In the preferred embodiment of the invention, a number of service processors are self-aggregated together in a single cluster.  FIG. 1  shows a system  100  in which the service processors  102   a ,  102   b , . . . ,  102   n  have been self-aggregated together in a single cluster, or complex,  102 . The service processors  102   a ,  102   b , . . . ,  102   n  may be the processors of the computing nodes of the system  100  (not specifically shown in  FIG. 1 ), in which each computing node includes varying hardware of the system  100 . The service processors  102   a ,  102   b , . . . ,  102   n  are self-clustered in that no controller, host, or other entity is responsible for their clustering. Rather, the service processors  102   a ,  102   b , . . . ,  102   n  discover themselves on their own to form the cluster  102 . 
     The service processors  102   a ,  102   b , . . . ,  102   n  appear as a single cluster  102  to an operating system (OS)  106  and a management console  108 . For instance, with respect to the OS  106 , the cluster  102  communicates with the OS  106  through a shared memory  104 . The memory  104  is shared by all the processors  102   a ,  102   b , . . . ,  102   n  within the cluster  102 . Communication between the cluster  102  and the OS  106  is such that the OS  106  is preferably unaware which of the processors  102   a ,  102   b , . . . ,  102   n  performs a given function. For example, the OS  106  may place a message in a part of the memory  104  allocated for a certain function, such that the one of the processors  102   a ,  102   b , . . . ,  102   n  responsible for this function monitors this part of the memory  104  and processes the message. 
     With respect to the console  108 , the console  108  preferably communicates through any one of the service processors  102   a ,  102   b , . . . ,  102   n  of the cluster  102 . As shown in  FIG. 1 , this is the service processor  102   b . The service processor  102   b  determines whether a message received from the console  108  is intended for one of the other service processors of the cluster  102 , or for itself, and routes the message accordingly. The console  108  is thus preferably unaware that the service processors  102   a ,  102   b , . . . ,  102   n  have been clustered as the cluster  102  to perform functionality for the console  108 . All communication between the console  108  and the cluster  102  is preferably handled through the service processor  102   b.    
     Technical Background 
       FIG. 2  shows a system  200  of a number of computing nodes  202   a ,  202   b , . . . ,  202   n , containing service processors  102   a ,  102   b , . . . ,  102   n , that communicate with one another over a service processor network  204 . The nodes  202   a ,  202   b , . . . ,  202   n  include hardware that make up the system  200 , and by which the nodes  202   a ,  202   b , . . . ,  202   n  perform functionality within the system  200 . The service processors  102   a ,  102   b , . . . ,  102   n , and more specifically the firmware thereof, manage the performance of this functionality. Firmware is software that is stored in hardware, such that the software is retained even after no power is applied to the hardware. The network  204  may be an Ethernet network, or another type of network. The firmware of the service processors  102   a ,  102   b , . . . ,  102   n , of the computing nodes  202   a ,  202   b , . . . ,  202   n , respectively, handles communication to and from the network  204 . 
       FIG. 3  shows a system  300  in which the management console  108  communicates with the service processor  102   b  of the node  202   b . The console  108  may be, for instance, a desktop computer. The console  108  communicates with the service processor  102   b  over the network  204 . However, the console  108  is only aware of the service processor  102   b . For instance, the console  108  may only know the network address of the service processor  102   b . Therefore, the console  108  only communicates with the service processor  102   b , as indicated by the dotted line  302 , even though it is communicatively connected to the network  204  over which all the service processors  102   a ,  102   b , . . . ,  102   n  communicate. 
       FIG. 4  shows a system  400  in which the operating system (OS)  106  communicates with the service processors  102   a ,  102   b , . . . ,  102   n  through the shared memory  104 . The shared memory  104  is shown as accessible to all the nodes  202   a ,  202   b , . . . ,  202   n , and thus to all the service processors  102   a ,  102   b , . . . ,  102   n  of these nodes. The shared memory  104  may be the memory of one or more of the nodes  202   a ,  202   b , . . . ,  202   n . The service processors  102   a ,  102   b , . . . ,  102   n  of the nodes  202   a ,  202   b , . . . ,  202   n  access the shared memory  104  through the nodes&#39; memory interconnect. 
     Self-Clustering of Service Processors 
       FIG. 5  shows a method  500  of an embodiment by which service processors self-aggregate as a single cluster or complex. The method  500  can be implemented in conjunction with the systems  100 ,  200 ,  300 , and  400  of  FIGS. 1 ,  2 ,  3 , and  4 , respectively. The method  500  can also be implemented in conjunction with an article of manufacture having a computer-readable signal-bearing medium. The medium may be a recordable data storage medium, a modulated carrier signal, or another type of medium. 
     The service processors first self-discover one another ( 502 ), such that the service processors are aggregated as a cluster. Each service processor also maintains an object map representing the hardware of the system for which it is responsible as objects ( 504 ). Two identifiers uniquely identify each object. The first identifier corresponds to the service processor on which the object resides. The second identifier distinguishes the object from other objects residing on the same service processor. 
       FIG. 6  shows diagrammatically the difference between these two identifiers. Within an example node  600 , there is a service processor  602 , and two pieces of hardware, a first hardware  604  and a second hardware  606 . The first identifier  608  identifies the service processor  602 . The second identifier  610  is associated with the object representing the first hardware  604 , whereas the second identifier  612  is associated with the object representing the second hardware  606 . Thus, the combination of the first identifier  608  and either the second identifier  610  or the second identifier  612  uniquely identifies the service processor  602  and a specific object instance uniquely identifying either the hardware  604  or  606 . For example, the combination of the first identifier  608  and the second identifier  610  uniquely identifies the service processor  602  as storing the object specifically representing the hardware  604 . 
     The first identifier  608  may be any identifier unique to the service processor  602 , such as the service processor&#39;s serial number or its Ethernet address. Other unique identifiers include combinations of one or more of the media access controller (MAC) address of the service processor  602 , and the port over which the service processor  602  communicates. The first identifier  608  may or may not include a network-related unique identifier. The second identifiers  610  and  612  may be the object instance numbers of the objects instantiated to represent the hardware  604  and  606 , respectively. For example, if the object representing the hardware  604  is initiated first, it may have an instance number of one, whereas if the object representing the hardware  606  is instantiated second, it may have an instance number of two. 
       FIG. 7  shows diagrammatically an example object map  700  that is stored on a given service processor. The object map  700  includes entries  702   a ,  702   b , and  702   c . Each of these entries identifies an object with a first identifier indicating the service processor on which the object is stored, which is the service processor storing the map  700 , and a second identifier distinguishing the object from other objects stored on this service processor. For example, entries  702   a ,  702   b , and  702   c  have first identifiers  704   a ,  704   b , and  704   c , respectively, that identify a service processor “A,” which is the service processor storing the map  700 . However, these entries have second identifiers  706   a ,  706   b , and  706   c , respectively, that identify different object instances “A-1,” “A-2,” and “A-3” that represent different hardware on the same node as the service processor “A.” Each service processor thus maintains an object map for the objects that are stored on the service processor. In this way, a global object map is distributed among all the service processors, where each service processor&#39;s own object map represents a part of the global object map. 
     Referring back to  FIG. 5 , self-discovery can specifically be performed by each service processor broadcasting a message to all the other service processors over the service processor network ( 506 ). This message includes the first identifier for its service processor, and alternatively also the second identifier for each object residing on the service processor. That is, the message identifies all the objects representing hardware on the same node of which the service processor is a part. Each service processor can also receive the messages broadcast from the other service processors over the network ( 508 ). Each of these messages, too, includes the first identifier and alternatively also the second identifier for each object residing on the service processor from which the message was received. Maintenance of the object map can specifically be performed by each service processor storing the first and the second identifiers for each object residing on itself in its object map ( 510 ). 
     The discovery process outlined in  FIG. 5  is a broadcast-type process, in which each service processor broadcasts a message to all other service processors. However, alternatively, the discovery process may be a multicast-type process, in which the service processors are segmented into two or more different groups. Each group may have associated therewith a specific multicast address. The service processors in a group broadcast their messages at this address, such that only the other processors in the group listen for these messages. In this way, each service processor sends a message only to the other service processor in the same group. The discovery process outlined in  FIG. 5  can be considered a multicast-type process where the service processors to which the messages are sent are only those service processors within a single group of service processors. 
     Embodiments of the invention can also incorporate a pre-discovery process not specifically outlined in  FIG. 5 . In pre-discovery, each service processor randomly generates a network address, such as an Internet Protocol (IP) address, within a given range, and sends a low-level message to the other devices on the network to ensure that the selected address has not already been taken by another device. If it has, the device with the same address sends a message back to the service processor, which generates another address and again sends a message. This process is repeated until the service processor has selected a unique network address. 
     Communication Between the Operating System and the Service Processors 
       FIG. 8  shows a method  800  of an embodiment by which communication between an operating system (OS) and a cluster of service processors is accomplished. The operating system is an example of a type of software code. Other types of software code include firmware, for instance. The method  800  can be implemented in conjunction with the systems  100  and  400  of  FIGS. 1 and 4 , respectively. The method  800  can also be implemented in conjunction with an article of manufacture having a computer-readable signal-bearing medium, such as a recordable data storage medium, a modulated carrier signal, or another type of medium. 
     The OS communicates with the cluster of service processors through a memory shared by all the service processors, such that the OS is preferably unaware which of the service processors performs a given function. First, the OS stores a message in a part of the shared memory allocated for a given type of messages ( 802 ). The service processor that has responsibility for this part of the shared memory, such that it is responsible for performing the functionality associated with the type of messages for which this part of the memory is allocated, processes the message ( 804 ). The service processor may, for instance, send data stored in the message over the service processor network  204  to the console  108 . The service processor then stores a response in the part of the shared memory ( 806 ), so that the OS is aware that the message has been properly processed. 
       FIG. 9  shows diagrammatically an example system  900  in which the shared memory  104  has been divided into parts  104   a ,  104   b ,  104   c ,  104   d , and  104   e . The service processor  102   a  is responsible for monitoring the parts  104   a  and  104   c  for messages from the OS  106 . That is, the service processor  102   a  is responsible for processing, or handling, the messages stored in the parts  104   a  and  104   c  by the OS  106 . Similarly, the service processor  102   b  is responsible for messages stored by the OS  106  in the parts  104   b  and  104   d , and the service processor  102   n  is responsible for messages stored by the OS  106  in the part  104   e . The parts  104   a ,  104   b ,  104   c ,  104   d , and  104   e  into which the memory  104  has been divided can be referred to as channels, such that each of the service processors  102   a ,  102   b , . . . ,  102   n  is responsible for a specific subset of these channels at different points in time. 
     The messages stored in the different parts of the memory  104 , and thus the channels into which the memory  104  has been divided, may be of different types. For example, a billboard type represents a generic memory data structure in which data is stored in the channel. A flow-controlled type represents a flow-controlled data structure in which the order of processing of the data is specified. A first-in-first-out (FIFO) type represents a FIFO-queuing data structure in which the first data stored is the first data processed. As a final example, an interrupt type represents a hardware feature which may be manipulated according to instructions stored in a data structure, to alert a service processor that a given event has occurred, such as work has arrived, such that particular actions may have to be performed. 
     Because each of the service processors  102   a ,  102   b , . . . ,  102   n  is responsible for a specific subset of the channels at different points in time, it is said that the channels are dynamically allocated among the service processors. Dynamic allocation of the channels among the service processors in particular allows for failover and load balancing among the service processors. For example, if one channel is receiving an inordinate amount of traffic, the other channels handled by the same responsible service processor may be dynamically allocated to other service processors, for load-balancing purposes. As another example, if a service processor fails, the channels for which it is responsible may be dynamically allocated to other service processors, for failover purposes. 
     Communication Between the Console and the Service Processors 
       FIG. 10  shows a method  1000  of an embodiment by which communication between a management console and a cluster of service processors is accomplished. The method  1000  can be implemented in conjunction with the systems  100  and  300  of  FIGS. 1 and 3 , respectively. The method  1000  can also be implemented in conjunction with an article of manufacture having a computer-readable signal-bearing medium, such as a recordable data storage medium, a modulated carrier signal, or another type of medium. 
     The console communicates with the cluster of service processors through any one of the service processors of a cluster, such that the console is preferably unaware that the service processors have been clustered to perform functionality for the console. This service processor first receives a message from the console ( 1002 ), and determines whether the message is intended for itself or another service processor within the cluster ( 1004 ). For instance, the message may relate to hardware that is stored in the same node as the service processor, or in the same node as another service processor. As another example, the message may relate to a function for which the service processor is responsible, or for which another service processor is responsible. 
     If the message is intended for the service processor that received the message, then this service processor processes the message appropriately ( 1006 ), and sends a response back to the console ( 1008 ). However, if the message is intended for a different service processor, the service processor that received the message sends, or routes, the message to this other service processor ( 1010 ), which itself processes the message. The service processor that received the message then receives a response from this other service processor ( 1012 ), which it routes back to the console ( 1014 ). 
     Other types of routing can also be accomplished of messages among service processors and the console, in addition to or in lieu of that shown specifically shown in  FIG. 10 . For example, if the service processor that receives a request from the console is not the intended service processor, it may route the message to the intended service processor, which directly sends a reply back to the console instead of routing the reply back to the service processor that had received the request. As another example, the console may send messages to specific service processors that it believes is responsible for processing such types of messages, which may be accomplished for performance, optimization, load balancing, and other purposes. 
     Furthermore, the console can become aware of a given object representing specific hardware on a specific service processor in a number of different ways not limited by the invention itself. The console may, for instance, ask for enumeration of the objects from the service processor it knows. For example, one of the service processors may maintain what is referred to as a service processor type root class node, which has the specific service processor instances as first-level children nodes. The children nodes of these first-level children nodes are second-level children nodes maintained by the individual service processors themselves, which can be directly queried for the enumeration of the second-level children nodes. The second-level children nodes may correspond to, for instance, the objects representing the hardware on a given service processor. 
     Advantages over the Prior Art 
     Embodiments of the invention allow for advantages over the prior art. The service processors of the nodes of a system aggregate themselves in a cluster, such that the operating system (OS) and the management console do not have added overhead responsibilities. That is, the service processors are clustered without assistance from a controller, host, master service processor, or other entity. This means that the OS and the console are not themselves required to perform service processor cluster management duties. 
     Because the OS places messages in different channels of memory shared among all the service processors, the OS is preferably unaware which of the service processors actually handles a given type of message. The OS thus does not have to track which service processors handle which types of messages, and, significantly, does not have to concern itself with load balancing and failover among the service processors. Similarly, the console communicates with the cluster of service processors through a given service processor, and thus is preferably unaware that the cluster is performing functionality for the console. The console also does not have to track which service processors handle which types of messages, and does not have to concern itself with load balancing and failover. 
     In addition, embodiments of the invention can be performed within the firmware of the service processor, avoiding modification of the OS to ensure compatibility. This means that significant coding effort is avoided to implement the invention in such embodiments, because the different types of operating systems that may be used do not have to be modified in order to implement the invention, since the invention is implemented in service processor firmware. Such service processor firmware implementation also increases behavioral consistency of service processor functionality from OS to OS. 
     Generic Alternative Embodiment 
     Aspects of the invention are applicable in other contexts besides an operating system (OS) communicating with a self-aggregated cluster of service processors through a shared memory.  FIG. 11  shows a system  1100  that is a generalization of the systems  100  and  400  of  FIGS. 1 and 4 , respectively. The entities  1102   a ,  1102   b , . . . ,  1102   n  self-aggregate into a cluster  1102 . For example, the entities may be service processors in the embodiment of the invention described in the previous sections of the detailed description. The host  1106  communicates with the cluster  1102  through a shared memory  1104 . For example, the host  1106  may be an OS in the embodiment of the invention described in the previous sections of the detailed description. Furthermore, the hardware that has been described as that for which the service processors are responsible in the embodiment described in the previous sections of the detailed description is one type of resource. 
     The shared memory  1104  is allocated into different parts, or channels, one or more of which each of the entities  1102   a ,  1102   b , . . . ,  1102   n  monitors for messages from the host  1106  for processing. Thus, communication between the host  1106  and the cluster  1102  can be accomplished as has been more particularly described in conjunction with the method  800  of  FIG. 8 , which is specific to the host  1106  being an OS and the entities  1102   a ,  1102   b , . . . ,  1102   n  being service processors. Otherwise, however, the method  800  of  FIG. 8  is applicable to the system  1100  as well. 
     As an example, the entities  1102   a ,  1102   b , . . . ,  1102   n  may be network adapters each having a given bandwidth, and which can self-discover one another to form the cluster  1102 . The bandwidth constituting the resource on the network adapters. The host  1106  may be an OS that sends data over the cluster  1102  through the shared memory  1104 . In this way, the OS does not have to be reconfigured to support multiple network adapters, but rather treats the cluster  1102  as a single, high-bandwidth network adapter. The adapters themselves handle failover, load balancing, and connection routing among the network adapters, such that the OS does not have to take on additional overhead for such functionality. 
     As another example, clustering of mass storage controllers may be performed, to allow a common queue of read/write/verify commands to be executed by any storage controller with access to the data. This is referred to as self-aggregating RAID. The number and type of storage controllers can vary, as well as which of them handles a particular region of clusters. The resources in this case are the storage devices, such as hard disk drives or other mass storage devices, managed by the mass storage controllers. Furthermore, the controllers may, for example, dynamically enable extra redundancy by initiating mirroring to unallocated storage, which is known as RAID- 1 , or initiating striping for regions experiencing large reads/writes, which is known as RAID- 0 . Another example is a cluster of coprocessors, such as floating point, vector, graphics, or other types of processors, which can result in high resource utilization with low overhead. 
     Other Alternative Embodiments 
     It will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. For example, whereas four different types of messages that can be communicated between the operating system (OS) and the cluster of service processors have been described, other types of messages can also be communicated between the OS and the cluster. As another example, the first identifier has been described as the Ethernet address of a service processor. However, other types and combinations of identifiers can also be used as the first identifier. 
     As another example, discovery of cluster peers can be accomplished by multicasting rather than broadcasting. The role ascribed to the OS can also be performed by other software code executing on the host, such as host firmware, a driver, a diagnostic program, and so on. Furthermore, the OS and/or the console may be aware of which service processor in the cluster is responsible for processing their requests, even though the invention has been substantially described as the OS and the console being unaware of which service processor is so responsible. In addition, whereas the invention has been substantially described as pertaining to a shared memory, it is also applicable to other types of shared resources, such as computer-readable media like hard disk drives and other storage media. Accordingly, the scope of protection of this invention is limited only by the following claims and their equivalents.