International Business Machines Corporation

Barbara A Maslak

James M Showalter

Thomas J Szczygielski

Kathryn Heninger Britton

James P Gray

Robert Bradley Bennett

Andrew P Citron

Edmond A Pruul

Michael K Ainsworth

Amos S Tanner

Timothy J Thatcher

Andrew Coleman

Mary E Vendryes

Cherie C Barnes

Richard L Stone

John A Henry

A computer system and process efficiently provides resource recovery for a failure during a commit procedure. An application is run on a processor and requests a work operation involving a resource such as a protected conversation with another application in a different real machine. A commit procedure is begun for the work request, and if the commit procedure fails before completion, the following steps are taken to optimize the use of one or both of the applications. At some time after the commit procedure fails, a return code is sent to at least the application that initiated the commit indicating the result of the application commit order and that the application can continue to run and does not have to wait for resynchronization (recovery). Then, while the initiating application continues to run and do other useful work, resynchronization is implemented in parallel, asynchronously.

Asynchronous resynchronization of a commit procedure

A computer system or network tailors scopes of commit processing by using local work unit identifiers and more global logical unit of work identifiers. The local work unit identifiers are used to identify the scope of commit processing within each execution environment, and the logical unit of work identifiers are used to identify related work units of different execution environments. The related work units are coupled to each other by a protected conversation between the execution environments.

Local and global commit scopes tailored to work units

In a computer system or process, sync point managers are distributed throughout each real machine for a plurality of execution environments, but all of the execution environments and sync point managers within one real machine share a common recovery facility and recovery log. A common recovery log is used by the recovery facility for all of the execution environments in the system. Different systems are interconnected by a communication facility and each has its own recovery facility and recovery log. A protected conversation can be initiated between the first and second execution environments in the same real machine, and the sync point managers within the respective execution environments coordinate the two-phase commit procedures associated with the protected conversations. A conversation manager within each real machine assists in routing the conversation between the first and second execution environments. Each resource manager, whether residing inside or outside of the real machine, has its own recovery log, but uses the recovery facility of the real machine that accesses the resource.

Coordinated sync point management of protected resources

To recover a failed commit procedure, a first recovery facility collects and compares sync point state information from a variety of different types of resources including a data repository and a protected conversation. The comparison of the sync point state information is made automatically in response to a sync point failure event. A second recovery facility serving another execution environment notifies the first recovery facility after a failure and subsequent recovery procedure of the second execution environment has completed. The first recovery facility makes automatic cyclic attempts to communicate with the second recovery facility. The first recovery facility can receive a manually initiated but automatically simulated response of sync point state information when there is a failure such that actual sync point state information cannot be received. The first recovery facility is responsive to the simulated sync point state information to proceed with a recovery operation substantially as if actual sync point state information were received.

Recovery facility for incomplete sync points for distributed application

A computer system provides registration of resource for synchronization point processing. Resources include file systems, data bases, and protected conversations. A resource becomes protected by the system when it is registered in the application's execution environment. The execution environment includes but is not exclusive to the interactive environment. Accordingly the invention provides an efficient and uniform method for identification of protected resources. The registration facility is separate from the application. Thus, the users of applications, application program developers, system administrators and operators need not have to consider or design a registration facility but only involve the one provided. A protected resource manager, through its adapter, can modify, at any time, the registration information, either by adding missing information or by changing the existing information. A resource registers only for the work unit in which it wishes to participate. An application could have several work units. A resource can register for two work units in the application or two resources can register for a single work unit or both.

Registration of resources for commit procedures

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Endwell, NY, United States of America

Barbara A Maslak