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: The present invention is a system that switches between non-secure and secure modes by making processes, applications and data for the non-active mode unavailable to the active mode. That is, non-secure processes, applications and data are not accessible when in the secure mode and visa versa. This is accomplished by creating dual hash tables where one table is used for secure processes and one for non-secure processes. A hash table pointer is changed to point to the table corresponding to the mode. The path-name look-up function that traverses the path name tree to obtain a device or file pointer is also restricted to allow traversal to only secure devices and file pointers when in the secure mode and only to non-secure devices and files in the non-secure mode. 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.

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 cluster of computing systems is provided with guaranteed real-time access to data storage in a storage area network. Processes issue requests 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: A cluster of computer system nodes share direct read/write access to storage devices via a storage area network using a cluster filesystem. Access to files on the storage devices is arbitrated by the cluster filesystem using tokens. Upon detection of a change in location of the metadata server, client nodes waiting for a token are interrupted to check on the status of at least one of data and node availability.

Abstract: In a computing system, cache coherency is performed by selecting one of a plurality of coherency protocols for a first memory transaction. Cache coherency is performed on appropriate caches in the computing system in accordance with the selected one of the plurality of coherency protocols. For a second memory transaction, another selection is made of the plurality of coherency protocols. The selected one of the coherency protocols for the second memory transaction may be the same as or different from the selected one of the plurality of coherency protocols for the first memory transaction.

Abstract: Systems and method for cooling computer systems are provided. A rack system for housing a plurality of computers is provided, the rack system including: a rack assembly configured to support a first stack of computers and a second stack of computers; and at least one fan assembly configured to create an airflow through the first stack of computers and into the second stack of computers. A method of cooling a plurality of computers in a rack system is provided, including: supporting a first stack of computers and a second stack of computers in a rack assembly; and effectuating an airflow through the first stack of computers and into the second stack of computers.

Abstract: A cluster of computer system nodes connected by a storage area network transmit messages using a messaging protocol having multiple layers. The storage area network supports computer system nodes running different operating systems on different endian processors. A heartbeat signal is transmitted in a common wire format over the lowest level of the messaging protocol; however other messages between the nodes may be transmitted in a format different from the common wire format. The node receiving a message is responsible for converting the format as necessary in a layer just above the layer of the messaging protocol handling heartbeat signals. However, conversion may be performed by the sending node if the sending node knows the format used by the receiving node.

Abstract: A computing system and method of operating a computing system is provided.

Abstract: A system for conveying information includes a signal transport device. The signal transport device includes a set of links operable to convey a first set of information signals from a first computer module to a second computer module and a link operable to convey a transaction request credit signal associated with the first set of information signals, the signal indicating whether at least a portion of a transaction request message may be sent using the first set of information signals. The device also includes a set of links operable to convey a second set of information signals in the opposite direction of the first set of information signals and a link operable to convey a transaction request credit signal associated with the second set of information signals, the signal indicating whether at least a portion of a transaction request message may be sent using the second set of information signals.

Abstract: A computer system comprising an interface assembly configured to support one or more I/O connections. In one variations 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 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 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.