Abstract: In distributed multinode data processing systems, mechanisms are employed to insure that the nodes are continually informed about the liveness of the other nodes within node groups in the network and across networks. The method of the present invention employs the concept of node stability which it uses to provide indications of membership in a previous stable group as part of messages transmitted in a protocol for forming, maintaining and dissolving node groupings in such a way as to assure that all of the nodes in the group have a consistent indication of liveness status for all of the nodes within any given group of nodes.

Abstract: Liveness determination in a multinode data processing system is enhanced through the use of a shared nonvolatile memory, typically a disk, which is utilized in conjunction with defined transmission protocols to provide an independent communication path usable for both the transmission of node liveness information and for other, more general, data transfer purposes. This path is considered as having the same degree of importance as other network paths and liveness indications from the shared memory path are likewise considered at the same time as liveness indications from another path or paths.

Abstract: The acquisition of a lock among nodes of a divided cluster is disclosed. A method is performable by each of at least one node of the cluster. A node waits for a delay corresponding to its identifier. The node asserts intent to acquire the lock by writing its identifier to X and Y variables where another node has failed to acquire the lock. The node waits for another node to acquire the lock where the other node has written to X, and proceeds where Y remains equal to its own identifier. The node waits for another node to acquire the lock where the other node has written to a Z variable, and writes its own identifier to Z and proceeds where the other node has failed. The node writes a value to Y indicating that it is acquiring the lock, and maintains acquisition by periodically writing to Z.

Abstract: Various components are provided to manage a clustered environment. These components include a System Registry that provides a global data storage; a Configuration manager that stores data locally on nodes of the clustered environment and globally within the System Registry; a Liveness component to provide status of communications paths of the cluster; a Group Services component that provides services to one or more other components of the clustered environment; and a Resource Management component that communicates with one or more resource controllers of the clustered environment. Each of the components of the clustered environment has one or more data and/or functional dependencies on one or more other components of the environment. However, relationships between the components are created such that the data and functional dependencies form an acyclic graph (i.e., a cycle of dependency relationships is avoided).

Abstract: The determination of node and/or adapter liveness in a distributed network data processing system is carried out via one messaging protocol that can be assisted by a second messaging protocol which is significantly less susceptible to delay, especially memory blocking delays encountered by daemons running on other nodes. The switching of protocols is accompanied by controlled grace periods for needed responses. This messaging protocol flexibility is also adapted for use as a mechanism for controlling the deliberate activities of node addition (birth) and node deletion (death).

Abstract: A topology propagation facility is provided for maintaining a common network topology database at different nodes in a distributed computing environment. The facility generates no message traffic when the distributed computing environment is in steady state. This is accomplished by discontinuing sending of group connectivity messages during a time period of no topology change within the distributed environment. Sending of group connectivity messages is reinitiated from at least one group leader upon identification by the group leader of at least one topology change within the distributed computing environment. Group connectivity messages are forwarded from one group of nodes on a first network to another group of nodes on a second network using a node common to both groups of nodes. The networks of the distributed computing environment can comprise heterogenous networks such that the topology propagation facility presented facilitates interoperability of the networks.

Abstract: A system, method and computer readable medium are provided for configuring network interfaces grouped into nodes for monitoring functionality. According to the method, a base address and subnet mask for the network interfaces are received, and a monitoring address is automatically generated for each of the network interfaces based on the base address, the subnet mask, and the nodes. The monitoring addresses is generated such that the monitoring address for each of the network interfaces is on a different subnet than the monitoring addresses for all of the other network interfaces in the same node as that network interface. Additionally, the monitoring addresses are assigned to the network interfaces for use by the monitoring process, with each of the monitoring addresses being assigned by being added as an additional network interface address of its network interface. Also provided is a method for monitoring functionality of network interfaces and providing fault recovery.

Abstract: The invention allows for dealing with failures that may result in split-brain situations. In particular the safe management of shared resources is supported even though the owners of a shared resource may be subject to split-brain situation. In addition our invention allows us to update the cluster configuration despite the fact that some members of the cluster cannot be reached during the reconfiguration. The policies imposed by our invention ensure that all nodes started always use the up-to-date configuration as working configuration or if that is not possible the administrator is warned about a potential inconsistency of the configuration.

Abstract: Liveness determination in a multinode data processing system is enhanced through the use of a shared nonvolatile memory, typically a disk, which is utilized in conjunction with defined transmission protocols to provide an independent communication path usable for both the transmission of node liveness information and for other, more general, data transfer purposes. This path is considered as having the same degree of importance as other network paths and liveness indications from the shared memory path are likewise considered at the same time as liveness indications from another path or paths.

Abstract: In distributed multinode data processing systems, mechanisms are employed to insure that the nodes are properly informed about the liveness of the other nodes in node groups in the network. In particular, the present invention employs group membership indicia as part of a mechanism for detecting that a node and/or its adapter have failed and have been recently restarted. Having detected this situation, group membership inconsistencies which it can engender are avoided.

Abstract: In distributed multinode data processing systems, mechanisms are employed to insure that the nodes are continually informed about the liveness of the other nodes within node groups in the network and across networks. The method of the present invention employs the concept of node stability which it uses to provide indications of membership in a previous stable group as part of messages transmitted in a protocol for forming, maintaining and dissolving node groupings in such a way as to assure that all of the nodes in the group have a consistent indication of liveness status for all of the nodes within any given group of nodes.

Abstract: The determination of node and/or adapter liveness in a distributed network data processing system is carried out via one messaging protocol that can be assisted by a second messaging protocol which is significantly less susceptible to delay, especially memory blocking delays encountered by daemons running on other nodes. The switching of protocols is accompanied by controlled grace periods for needed responses. This messaging protocol flexibility is also adapted for use as a mechanism for controlling the deliberate activities of node addition (birth) and node deletion (death).