Abstract: A cluster of computer system nodes share direct read/write access to storage devices via a storage area network using a cluster filesystem. At least one trusted metadata server assigns a mandatory access control label as an extended attribute of each filesystem object regardless of whether required by a client node accessing the filesystem object. The mandatory access control label indicates the sensitivity and integrity of the filesystem object and is used by the trusted metadata server(s) to control access to the filesystem object by all client nodes.

Abstract: A system, method, and computer program product are provided for remote rendering of computer graphics. The system includes a graphics application program resident at a remote server. The graphics application is invoked by a user or process located at a client. The invoked graphics application proceeds to issue graphics instructions. The graphics instructions are received by a remote rendering control system. Given that the client and server differ with respect to graphics context and image processing capability, the remote rendering control system modifies the graphics instructions in order to accommodate these differences. The modified graphics instructions are sent to graphics rendering resources, which produce one or more rendered images. Data representing the rendered images is written to one or more frame buffers. The remote rendering control system then reads this image data from the frame buffers. The image data is transmitted to the client for display or processing.

Abstract: Resource acquisition requests for a filesystem are executed under user configurable metering. Initially, a system administrator sets a ratio of N:M for executing N read requests for M write requests. As resource acquisition requests are received by a filesystem server, the resource acquisition requests are sorted into queues, e.g., where read and write requests have at least one queue for each type, plus a separate queue for metadata requests as they are executed ahead of any waiting read or write request. The filesystem server controls execution of the filesystem resource acquisition requests to maintain the ratio set by the system administrator.

Abstract: A processor interface (24) receives a flush request from a processor (700) and performs a snoop operation to determine whether the data is maintained in a one of the local processors (700) and whether the data has been modified. If the data is maintained locally and it has been modified, an identified local processor (700) receives the flush request from the processor interface (24) and initiates a writeback to a memory directory interface unit (24). If the data is not maintained locally or has not been modified, the processor interface (24) forwards the flush request to the memory directory interface unit (22). Memory directory interface unit (22) determines which remote processors within the system (10) have a copy of the data and forwards the flush request only to those identified processors.

Abstract: A computer system with read/write access to storage devices creates a snapshot of a data volume at a point in time while continuing to accept access requests to the mirrored data volume by copying before making changes to the base data volume. Multiple snapshots may be made of the same data volume at different points in time. Only data that is not stored in a previous snapshot volume or in the base data volume are stored in the most recent snapshot volume.

Abstract: A cluster of computing systems is provided with guaranteed real-time access to data storage in a storage area network. Processes issue request for bandwidth reservation which are initially handled by a daemon on the same node as the requesting processes. The local daemon determines whether bandwidth is available and, if so, reserves the bandwidth in common hardware on the local node, then forwards requests for shared resources to a master daemon for the cluster. The master daemon makes similar determinations and reservations for resources shared by the cluster, including data storage elements in the storage area network and grants admission to the requests that don't exceed total available bandwidth.

Abstract: This relates to the manner in which computers are configured in a given area in order to conserve space and to deal with cooling issues associated with the close housing of a large number of computers. Efficient arrangements for efficiently increasing the density of computer configurations are shown, particularly when used in a network server or host environment.

Abstract: A system, method, and computer program product are provided for remote rendering of computer graphics. The system includes a graphics application program resident at a remote server. The graphics application is invoked by a user or process located at a client. The invoked graphics application proceeds to issue graphics instructions. The graphics instructions are received by a remote rendering control system. Given that the client and server differ with respect to graphics context and image processing capability, the remote rendering control system modifies the graphics instructions in order to accommodate these differences. The modified graphics instructions are sent to graphics rendering resources, which produce one or more rendered images. Data representing the rendered images is written to one or more frame buffers. The remote rendering control system then reads this image data from the frame buffers. The image data is transmitted to the client for display or processing.

Abstract: A cluster of computer system nodes share direct read/write access to storage devices via a storage area network using a cluster filesystem. At least one trusted metadata server assigns a mandatory access control label as an extended attribute of each filesystem object regardless of whether required by a client node accessing the filesystem object. The mandatory access control label indicates the sensitivity and integrity of the filesystem object and is used by the trusted metadata server(s) to control access to the filesystem object by all client nodes.

Abstract: A computer system with read/write access to storage devices creates a snapshot of a data volume at a point in time while continuing to accept access requests to the mirrored data volume by copying before making changes to the base data volume. Multiple snapshots may be made of the same data volume at different points in time. Only data that is not stored in a previous snapshot volume or in the base data volume are stored in the most recent snapshot volume.

Abstract: A method for maintaining data coherency in a shared-memory computer system having a plurality of nodes divides the local memory of a given node into one or more blocks and stores a data record for each block indicating a plurality of node groups and a selection of the node groups. Each selected node group represents a number of nodes, and selected node groups represent at least one node that has requested access to the block. In response to receiving an access request from a requesting node that may or may not be in a selected node group, the method and system update the data record to indicate the correct selection. If the requesting node is not in any node group, the data record is adjusted to have new node groups, one of which represents the requesting node.

Abstract: A system for establishing a primary master node in a computer system includes a plurality of nodes, each node configured with an update interval, a hierarchy of master nodes selected from the plurality of nodes, wherein the master nodes are configured to synchronize the plurality of nodes with a clock value by sending out its clock value when its update interval has expired, wherein each node resets its update interval when it receives the clock value, a primary master node selected from the hierarchy of master nodes based on its update interval, and at least one backup master node selected from the hierarchy of master nodes based on its update interval, the backup master node configured to become the primary master node when the plurality of nodes do not receive the clock value after a predetermined period of time has elapsed.

Abstract: Computing resources shared by local and network filesystems may be used to maximum capacity by a single application, or equitably shared by multiple applications under heavy load. A portion of the resources are set aside for local filesystem use and a small number is reserved for each network filesystem. The remaining resources may be used by either local or network filesystems. An enforcement limit puts a ceiling on the number of resources that can be used by a single network filesystem. When the enforcement limit is applied to a filesystem, the number of executing resource acquisition requests from that filesystem is reduced, by completion of the requests, to the reserved number of resources for that filesystem before any more resources acquisition requests from that filesystem are executed.

Abstract: A system and method for interconnecting a plurality of processing element nodes within a scalable multiprocessor system is provided. Each processing element node includes at least one processor and memory. A scalable interconnect network includes physical communication links interconnecting the processing element nodes in a cluster. A first set of routers in the scalable interconnect network route messages between the plurality of processing element nodes. One or more metarouters in the scalable interconnect network route messages between the first set of routers so that each one of the routers in a first cluster is connected to all other clusters through one or more metarouters.

Abstract: A system switches between non-secure and secure modes by making processes, applications, and data for the non-secure mode unavailable to the secure mode and vice versa. The process thread run queue is modified to include a state flag for each process that indicates whether the process is a secure or non-secure process. A process scheduler traverses the queue and only allocates time to processes that have a state flag that matches the current mode. Running processes are marked to be idled and are flagged as unrunnable, depending on the security mode, when the process reaches an intercept point. The scheduler is switched to allow only threads that have a flag that corresponding to the active security mode to be run.

Abstract: A rack mounted computer system. In one variation the computer rack is configured for side-by-side placement of computers. In another variation, the computer rack includes flanges for supporting the placement of computer units within the rack. In another variation the computer rack is configured with retaining clips. In yet another variation, the computer rack is configured to receive computers with chassis that are adapted for side-by-side placement.

Abstract: A system, method, and computer program product are provided for remote rendering of computer graphics. The system includes a graphics application program resident at a remote server. The graphics application is invoked by a user or process located at a client. The invoked graphics application proceeds to issue graphics instructions. The graphics instructions are received by a remote rendering control system. Given that the client and server differ with respect to graphics context and image processing capability, the remote rendering control system modifies the graphics instructions in order to accommodate these differences. The modified graphics instructions are sent to graphics rendering resources, which produce one or more rendered images. Data representing the rendered images is written to one or more frame buffers. The remote rendering control system then reads this image data from the frame buffers. The image data is transmitted to the client for display or processing.

Abstract: A method and apparatus for maintaining data coherency in a computer system having a plurality of nodes forms a directory by grouping the nodes into a plurality of hierarchical groups of two or more levels. The method and apparatus also 1) set the directory to have data relating to a first set of groups within a first level, and 2) determine if a requesting node requesting data is a member of one of the first set of groups. The directory then is set to have data relating to a second group of nodes if the requesting node is determined not to be a member of the first set of groups within the first level. The second group of nodes is in a higher level than the first level.

Abstract: In a computing system, cache coherency is performed by selecting one of a plurality of coherency protocols for a first memory transaction. Each of the plurality of coherency protocols has a unique set of cache states that may be applied to cached data for the first memory transaction. Cache coherency is performed on appropriate caches in the computing system by applying the set of cache states of the selected one of the plurality of coherency protocols.

Abstract: A cluster of computer system nodes connected by a storage area network include two classes of nodes. The first class of nodes can act as clients or servers, while the other nodes can only be clients. The client-only nodes require much less functionality and can be more easily supported by different operating systems. To minimize the amount of data transmitted during normal operation, the server responsible for maintaining a cluster configuration database repeatedly multicasts the IP address, its incarnation number and the most recent database generation number. Each node stores this information and when a change is detected, each node can request an update of the data needed by that node. A client-only node uses the IP address of the server to connect to the server, to download the information from the cluster database required by the client-only node and to upload local disk connectivity information.