Unisys Corporation

James Roffe

Edward Stafford

Donald N Hester, Jr

Gary Schlaff

Sheridan L Natwick

Techniques are described of using votes of third-party components to select a master processor from a plurality of redundant processors. A master processor and a standby processor maintain communications with one another. If communication between the master processor and the standby processor fails, the processors may poll a set of registered voters to determine which of the processors is to be the master processor. In this way, the processors may determine which of the processors is to be master without the use of a shared indicator to specify which of the processors is to be the master processor.

Third-party voting to select a master processor within a multi-processor computer

A method and apparatus for persisting object oriented data are provided in various embodiments. Persistent storage is established for a working data set and a committed data set. The areas for the working and committed data sets are used for storage of the persistent data objects. After a persistent data object is updated in computer memory, the updated version is written to the working data set. Then, references to the working data set and the committed data set are switched, whereby the working data set becomes the committed data set and the committed data set becomes the working data set.

Method and apparatus for persisting object oriented data

A method and apparatus for allowing a user program, which has provided a global transaction to a remote system, to continue operation after only a partial recovery, thereby significantly reducing the delay associated with a detected fault or failure. The local transaction steps may be recovered by the local system. For all global transaction steps in a 'ready' state, a data base management system may re-establish the data base locks and system environment variables associated therewith. Thereafter, the user programs may continue operation and may access the un-locked portion of the data base, including the portion associated with the local transactions. In the meantime, a transaction manager may determine the actual status of the global transaction steps by performing the necessary communications with the remote systems. Once the actual status of a particular global transaction step is determined by the transaction manager, the global transaction step may be recovered, and the corresponding data base locks may be released. As the transaction manager determines the actual state of the remaining global transaction steps, more of the data base may be released to the user programs. Eventually, the entire data base may be available to the user programs.

Method for making a data base available to a user program during data

A method and apparatus for coordinating activities of data base management systems operable on Closely-Coupled Host Processors. In particular, messages can be quickly passed between data base management systems executing on Host Processors which are coupled to a Record Lock Processor. One or more receiver processes register with the operating system to receive messages. When the operating system detects a message a Receiver Process begins processing the message. When a data base management system detects that other data base management systems should be notified of an event, a message sending interface is called with a parameter which indicates particular Host Processors and a parameter containing the message to send, and the message is sent to the Host Processors specified. Programs sending messages may elect to have execution suspended until a response message is received from the other Host Processors. When a program which has sent a message is suspended, information regarding the suspended program is placed in a queue which stores information from other suspended programs. A timeout function periodically checks the queue for programs which have been suspended for an extended length of time, and resumes execution of those suspended programs where the time for which the program has been suspended exceeds some predetermined length of time.

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Lino Lakes, MN, United States of America

James Roffe