International Business Machines Corporation

Earle H Jenner

Michael Gerard Mall

Richard Dievendorff

Stuart L Silen

Margaret K LaBelle

Roger L Brockmeyer

Daniel E House

An extension of the two phase commit protocol allows distributed participation among physically distant agents independent of the communications mechanism being used in a data processing system. An extra stage of processing is added to the two phase commit protocol called End Phase One Processing (EPOP) which enables a distribution of the coordinator function across systems using any communication mechanism. EPOP is an extra stage in which a participant can receive control. In this extra stage, a participant flows two phase commit protocol sequences to distributed systems. The communication mechanism is used in such a way that it becomes part of a distributed coordinator. The coordinator itself does not need knowledge of other systems. The extra stage of processing is enabled by an operating system service called Enable End Phase One Exit Processing (EEPOEP). EEPOEP causes an extension of two phase commit protocol to be used on the issuing system. In this way, not only distributed databases can be supported, but also distributed users and distributed generic resource managers. A new response, called ABSTAIN, can be used by a resource manager in response to a PREPARE signal from the coordinator. This response from the resource manager to the coordinator indicates that the resource manager wants to continue to be involved with the unit of work two phase commit process but does not want to influence the final decision (i.e., COMMIT or BACKOUT) of the unit of work.

Extension of two phase commit protocol to distributed participants

A programming method and structure for operating a computing system to restart a total subsystem or a subset of that subsystem to an operable state following a total interruptions (system failure or termination, either normal or abnormal). The subsystem isolates inoperable resources while permitting the others to resume by independently maintaining in a first structure recording the completion state of a resource manager's recovery responsibility with respect to each interrupted work unit and in a second structure the operational states and recovery log interest scopes of each resource manager. The completion state can be influenced by the starting or not of a resource manager, and if restarted, the presence or absence of a resource subset required to accomplish the work unit recovery.

Method and apparatus for restarting a computing system

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Earle H Jenner