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.

Abstract: A system and method for conveying data include the capability to determine whether a transaction request credit has been received at a computer module, the transaction request credit indicating that at least a portion of a transaction request message may be sent. The system and method also include the capability to determine, if a transaction request message is to be sent, whether at least a portion of the transaction request message may be sent and to send the at least a portion of the transaction request message if it may be sent.

Abstract: A processor may operate in one of a plurality of operating states. In a Normal operating state, the processor is not involved with a memory transaction. Upon receipt of a transaction instruction to access a memory location, the processor transitions to a Transaction operating state. In the Transaction operating state, the processor performs changes to a cache line and data associated with the memory location. While in the Transaction operating state, any changes to the data and the cache line is not visible to other processors in the computing system. These changes become visible upon the processor entering a Commit operating state in response to receipt of a commit instruction. After changes become visible, the processor returns to the Normal operating state. If an abort event occurs prior to receipt of the commit instruction, the processor transitions to an Abort operating state where any changes to the data and cache line are discarded.

Abstract: A system and method for remote rendering of computer graphics wherein user transactions are reliable and the transmission of rendered graphics is relatively fast. The invention is implemented in a client server context, where a computer graphics application and rendering resources are located at a server. A user controls the graphics application through a client machine connected to the server through a computer network. The user's commands are sent from the client to the server, while rendered computer graphics are transmitted from the server to a display at the client. Different transport protocols are used, depending on the requirements of a particular transmission. Data related to user interactions is transmitted using a relatively reliable transport protocol, such as TCP. Rendered subject graphics data is transmitted from the server to the client using a less reliable but faster transport protocol, such as UDP.

Abstract: Processing transaction requests in a shared memory multi-processor computer network is described. A transaction request is received at a servicing agent from a requesting agent. The transaction request includes a request priority associated with a transaction urgency generated by the requesting agent. The servicing agent provides an assigned priority to the transaction request based on the request priority, and then compares the assigned priority to an existing service level at the servicing agent to determine whether to complete or reject the transaction request. A reply message from the servicing agent to the requesting agent is generated to indicate whether the transaction request was completed or rejected, and to provide reply fairness state data for rejected transaction requests.

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 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: In an embodiment, a system includes a resource. The system also includes a first processor having a load/store functional unit. The load/store functional unit is to attempt to access the resource based on access requests. The first processor includes a congestion detection logic to detect congestion of access of the resource based on a consecutive number of negative acknowledgements received in response to the access requests prior to receipt of a positive acknowledgment in response to one of the access requests within a first time period.

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 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 cpu-set type multiprocessor system allows a cpu of a cpu-set that has a hardware exception to disable itself and notify the system. The system assigns processes of the cpu-set that include the problem cpu to another cpu-set. The disabling of the problem cpu and transfer of the related processes to another cpu-set allows the system to failsoft so that other cpu-sets the multiprocessor system can continue to run and a recovery of the processes being run on the problem cpu-set occurs.

Abstract: A system and method of reducing skew between a plurality of signals transmitted with a transmit clock is described. Skew is detected between the received transmit clock and each of received data signals. Delay is added to the clock or to one or more of the plurality of data signals to compensate for the detected skew. The delay added to each of the plurality of delayed signals is updated to adapt to changes in detected skew.

Abstract: A system for implementing a failover policy includes a cluster infrastructure for managing a plurality of nodes, a high availability infrastructure for providing group and cluster membership services, and a high availability script execution component operative to receive a failover script and at least one failover attribute and operative to produce a failover domain. In addition, a method for determining a target node for a failover comprises executing a failover script that produces a failover domain, the failover domain having an ordered list of nodes, receiving a failover attribute and based on the failover attribute and failover domain, selecting a node upon which to locate a resource.

Abstract: A cluster of computer system nodes share direct read/write access to storage devices via a storage area network using a cluster filesystem and operating system implementing DMAPI. Threads executing on a metadata client know when a DMAPI event is required, and generate the DMAPI event on their own initiative when necessary. A metadata server maintains DMAPI queues. If the metadata server relocates to another host, the DMAPI events in the DMAPI queues are moved transparently to users.

Abstract: A cluster of computer system nodes share direct read/write access to storage devices via a storage area network using a cluster filesystem. Version information about subsystems is acquired by a leader node when forming a cluster membership and distributed to all nodes in the cluster to enable proper messaging during operation.

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 computer system comprising an interface assembly configured to support one or more I/O connections. In one variation, the computer system comprises a main board housed within a chassis, a chassis connector coupled to the chassis, and one or more I/O cables coupled to the chassis connector. In another variation, the computer assembly comprises a computer rack with a plurality of connector interfaces, each of which is adapted for engaging a computer through a chassis connector with a plurality of I/O ports.

Abstract: A processor may operate in one of a plurality of operating states. In a Normal operating state, the processor is not involved with a memory transaction. Upon receipt of a transaction instruction to access a memory location, the processor transitions to a Transaction operating state. In the Transaction operating state, the processor performs changes to a cache line and data associated with the memory location. While in the Transaction operating state, any changes to the data and the cache line is not visible to other processors in the computing system. These changes become visible upon the processor entering a Commit operating state in response to receipt of a commit instruction. After changes become visible, the processor returns to the Normal operating state. If an abort event occurs prior to receipt of the commit instruction, the processor transitions to an Abort operating state where any changes to the data and cache line are discarded.