Abstract: A method is provided for continuing node operations in quorum-based protocols. This is particularly valuable in the situation in which a group of nodes includes only two nodes and in which communications to a node is lost. Provision is made for adding additional status indications to each node indicating whether or not it is enabled for single-node quorum operation. Provision is also made for identifying one node as a primary node and another node as a secondary node for time-out response purposes.

Abstract: In a multinode data processing system capable of partitioning operations a method is provided for adding nodes to a configuration of nodes in a manner which node quorums are employed but in which two quorum values (ideal and enforced) are employed and in which old nodes using a given file system are distinguished from new nodes. The method prevents even the transient use of inappropriate quorum values.

Abstract: Communication between different entities of a computing environment is facilitated by an address mapping capability. Messages are sent between the entities to have desired tasks performed. Instead of providing within the messages the actual non-logical addresses (e.g., virtual, real addresses) used to perform the tasks, logical addresses are provided. The logical addresses are then mapped to the non-logical addresses. Each logical address can map to a plurality of non-logical addresses.

Abstract: In a multinode data processing system capable of partitioning operations a method is provided for adding nodes to a configuration of nodes in a manner which node quorums are employed but in which two quorum values (ideal and enforced) are employed and in which old nodes using a given file system are distinguished from new nodes. The method prevents even the transient use of inappropriate quorum values.

Abstract: A system and method for message processing in a distributed, multi-node data processing system is structured to permit a sending process running on one node to send messages to a selectable subset of nodes via an interface mechanism which places a sending process in an inactive or idle state pending receipt of either all responses from the selected destination nodes or of a notification via the interface that one or more responses will not arrive.

Abstract: Communication between different entities of a computing environment is facilitated by an address mapping capability. Messages are sent between the entities to have desired tasks performed. Instead of providing within the messages the actual non-logical addresses (e.g., virtual, real addresses) used to perform the tasks, logical addresses are provided. The logical addresses are then mapped to the non-logical addresses. Each logical address can map to a plurality of non-logical addresses.

Abstract: Interconnected data processing nodes can from time to time experience temporary failures or losses of communication links between system nodes. In systems which have a mechanism for determining whether the data processing nodes are operative or not, by providing an epoch number for use as an instance identifier and by providing a mechanism for controlling the generation and propagation of the epoch number, such systems are able to resume their respective tasks when failed nodes or communication links are restored.

Abstract: A method is provided for continuing node operations in quorum-based protocols. This is particularly valuable in the situation in which a group of nodes includes only two nodes and in which communications to a node is lost. Provision is made for adding additional status indications to each node indicating whether or not it is enabled for single-node quorum operation. Provision is also made for identifying one node as a primary node and another node as a secondary node for time-out response purposes.

Abstract: A computer system having a shared disk file system running on multiple computers each having their own instance of an operating system and being coupled for parallel data sharing access to files residing on network attached shared disks. Locking techniques reduce the overhead of a token manager which is also used in the file system recovery if a computer participating in the management of shared disks becomes unavailable or failed. Synchronous and asynchronous takeover of a metadata node occurs for correction of metadata which was under modification and a new computer node to be a metadata node for that file. Locks are not constantly required to allocate new blocks on behalf of a user.