Abstract: A method and system for backing up primary nodes onto backup nodes where the primary nodes can each originate a distributed transaction and can participate in a distributed transaction. The backup nodes, after a primary node failure, undo all transactions whose state is unknown on the backup node and all committed transactions which, if kept, would lead to an inconsistent set of backup nodes. First, committed transactions are undone if commits for them were not received on all back up nodes to the primary nodes that participated in the transaction. Second, all committed transactions that potentially depend on the committed transactions that were undone are also undone. Only those transactions that are provably independent of the committed transactions that were undone are kept. The result is a set of back up nodes which can support operations until the failing primary node is restored.

Abstract: A method and system for high-speed database replication. Audit update records and audit backout records are generated by the primary system, and are transmitted to the backup system in multiple streams in parallel. The backup system stores the received audit records as audit image trails, and applies the audit updates and audit backouts to the backup database without regard to whether the transactions committed or aborted and without regard to whether the backup system received a complete set of the audit records pertaining to the transactions. Upon the occurrence of a predetermined event, the backup system applies all the audit updates and backouts it received, and subsequently “undoes” questionable audit updates and audit backouts.

Abstract: A method and system for purging database update image files after completion of associated transactions for a database replication system with multiple audit logs. Audit update records and audit backout records are generated by the primary system, and are transmitted to the backup system in multiple streams in parallel. The backup system stores the received audit records as audit image trails, and applies the audit updates and audit backouts to the backup database without regard to whether the associated transactions committed or aborted. Because audit updates and audit backouts are applied without regard to whether the associated transactions committed or aborted, image files containing audit records associated with transactions that have not yet committed or aborted must not be purged. The present invention provides for a method for determining whether an image trail file contains audit records that can be purged such that image trail files can be safely deleted.

Abstract: A method and system for purging database update image files after completion of associated transactions for a database replication system with multiple audit logs. Audit update records and audit backout records are generated by the primary system, and are transmitted to the backup system in multiple streams in parallel. The backup system stores the received audit records as audit image trails, and applies the audit updates and audit backouts to the backup database without regard to whether the associated transactions committed or aborted. Because audit updates and audit backouts are applied without regard to whether the associated transactions committed or aborted, image files containing audit records associated with transactions that have not yet committed or aborted must not be purged. The present invention provides for a method for determining whether an image trail file contains audit records that can be purged such that image trail files can be safely deleted.

Abstract: A primary computer system has a database, application programs that modify the local database, and a transaction manager that stores audit records in a local image trail reflecting those application program modifications to the local database. In a remote backup system, a Receiver process receives audit records from the primary system. The audit records include audit update and audit backout records indicating database updates and database backouts generated by transactions executing on the primary system. The Receiver stores the audit update and audit backout records in one or more image trails. For each image trail there is an Updater process that applies to a backup database volume the database updates and backouts indicated by the audit update and audit backout records in the image trail.

Abstract: A primary computer system has a database, application programs that modify the local database, and a transaction manager that stores audit records in a local image trail reflecting those application program modifications to the local database. In a remote backup system, a Receiver process receives audit records from the primary system. The audit records include audit update and audit backout records indicating database updates and database backouts generated by transactions executing on the primary system. The Receiver stores the audit update and audit backout records in one or more image trails. For each image trail there is an Updater process that applies to a backup database volume the database updates and backouts indicated by the audit update and audit backout records in the image trail. The remote backup system periodically executes a file purge procedure, which identifies the oldest transaction table from among the transaction tables in the last image trail file accessed for each of the image trails.

Abstract: A remote data facility (RDF) capable of performing a lockstep data replication procedure (“LockStep Procedure”). When the LockStep Procedure is invoked, and when an application program has committed a transaction, the application program is prevented from executing other procedures until the application is notified that audit records associated with that transaction have been safely stored to the backup system. Since the application program is prevented from executing other procedures, no decision based on the commit will be made until after the application is notified that all the audit records associated with the transaction are safely stored in the backup system.

Abstract: A method and system for high-speed database replication. Audit update records and audit backout records are generated by the primary system, and are transmitted to the backup system in multiple streams in parallel. The backup system stores the received audit records as audit image trails, and applies the audit updates and audit backouts to the backup database without regard to whether the transactions committed or aborted and without regard to whether the backup system received a complete set of the audit records pertaining to the transactions. Upon the occurrence of a predetermined event, the backup system applies all the audit updates and backouts it received, and subsequently “undoes” questionable audit updates and audit backouts.

Abstract: A method and system for purging database update image files after completion of associated transactions for a database replication system with multiple audit logs. Audit update records and audit backout records are generated by the primary system, and are transmitted to the backup system in multiple streams in parallel. The backup system stores the received audit records as audit image trails, and applies the audit updates and audit backouts to the backup database without regard to whether the associated transactions committed or aborted. Because audit updates and audit backouts are applied without regard to whether the associated transactions committed or aborted, image files containing audit records associated with transactions that have not yet committed or aborted must not be purged. The present invention provides for a method for determining whether an image trail file contains audit records that can be purged such that image trail files can be safely deleted.

Abstract: A method and system for backing up primary nodes onto backup nodes where the primary nodes can each originate a distributed transaction and can participate in a distributed transaction. The backup nodes, after a primary node failure, undo all transactions whose state is unknown on the backup node and all committed transactions which, if kept, would lead to an inconsistent set of backup nodes. First, committed transactions are undone if commits for them were not received on all back up nodes to the primary nodes that participated in the transaction. Second, all committed transactions that potentially depend on the committed transactions that were undone are also undone. Only those transactions that are provably independent of the committed transactions that were undone are kept. The result is a set of back up nodes which can support operations until the failing primary node is restored.

Abstract: A local computer system has a local database, application programs that modify the local database, and a transaction manager that stores audit records in a local audit trail reflecting those application program modifications to the local database. Each audit record has an associated audit trail position. A remotely located computer system has a backup database. A remote data duplication facility (RDF) is partially located in the local computer system and partially in the remote computer for maintaining virtual synchronization of the backup database with the local database. The RDF includes an extractor process executed by said local computer system, and a receiver process and a plurality of updater processes executed by the remote computer system. The extractor process extracts audit records from the local audit trail and transmits those records to the receiver process.

Abstract: An improved recovery method utilizes sequence numbers to order log records and reduce the excess compensating actions due to a failure during recovery. Next undo records are written to the log after a preset number of compensating actions which include the sequence number of the record currently being scanned. After a failure, all records between the next undo record and the record having the sequence number included in the next undo record are ignored during when the log is scanned backwards.

Abstract: A primary computer system has a database, application programs that modify the local database, and a transaction manager that stores audit records in a local audit trail reflecting those application program modifications to the local database. A plurality of parallel backup systems are used to provide "triple contingency protection" of the data on the primary computer system. However, if the primary system suffers a sudden catastrophic failure, the parallel backup systems will generally be left in inconsistent states. To restart the application programs on one of the backup system, the parallel backup are first synchronized with each other, and then transaction processing is restarted with one of the backup systems as the new primary system, and the other backup systems as the backups to the new primary system.

Abstract: A primary computer system has a database, application programs that modify the local database, and a transaction manager that stores audit records in a local audit trail reflecting those application program modifications to the local database. A plurality of parallel backup systems are used to provide "triple contingency protection" of the data on the primary computer system. However, if the primary system suffers a sudden catastrophic failure, the parallel backup systems will generally be left in inconsistent states. To restart the application programs on one of the backup system, the parallel backup are first synchronized with each other, and then transaction processing is restarted with one of the backup systems as the new primary system, and the other backup systems as the backups to the new primary system.

Abstract: A local computer system has local database, application programs that modify the local database, an a transaction manager that stores audit records in a local audit trail reflecting those application program modifications to the local database. A remotely located computer system has a backup database. A remote data duplication facility (RDF) is partially located in the local computer system and partially in the remote computer for maintaining virtual synchronization of the backup database with the local database. The RDF includes an extractor process executed by said local computer system, and a receiver process and a plurality of updater processes executed by the remote computer system. The extractor process extracts audit records from a local audit trail and transmits those records to the receiver process. The receiver process distributes the audit records into one or more image trail files that are associated with a particular updater process.

Abstract: A local computer system has a local database, application programs that modify the local database, and a transaction manager that stores audit records in a local audit trail reflecting those application program modifications to the local database. A remotely located computer system has a backup database. A remote data duplication facility (RDF) maintains virtual synchronization of the backup database with the local database. The RDF includes an extractor process executed by the local computer system, and a receiver process and a plurality of updater processes executed by the remote computer system. The extractor process extracts audit records from the local audit trail and transmits those records to the receiver process. The receiver distributes the received audit records to a plurality of image trail files in the remote computer system for processing by updater processes, which initiate redo operations of database modifications denoted in at least a subset of the audit records against the backup database.

Abstract: A local computer system has a local database, application programs that modify the database and a transaction manager that stores audit records in a local audit trail reflecting the application programs' modifications to the local database. A remote computer system has a backup database. A remote data duplication facility (RDF) is distributed in the local computer system and the remote computer for maintaining synchronization of the backup database with the local database. The RDF has an extractor process and a receiver process. The extractor process has multiple updater processes, extracts audit records from the local audit trail and transmits them to the receiver process, which distributes them to the updater processes which in tuna initiate redo operations of database modifications in at least a subset of the audit records against the backup database.