Database Recovery
Reality supports the following recovery methods:
Process Recovery
Process Recovery is an automatic recovery mode which restores a database to a consistent state after a process has crashed or been killed.
This recovery method is supported by Transaction Handling, if configured on the database. When a failure occurs, it rolls back all changes in incomplete transactions, restoring their Before images, so that the data on the failed machine is restored to the state that it was in before the incomplete transactions started.
Where distributed transactions are being used, the automatic recovery process is controlled by the remote Transaction Manager, Microsoft's Distributed Transaction Co-ordinator (MDTC). Transaction branches that have not been prepared are aborted and their updates rolled back. Transaction branches that have been prepared may be either aborted or committed, the decision being the responsibility of the MDTC.
Rapid Recovery
Following a system or application failure, you can use the realrecover command to recover databases that are configured for Rapid Recovery and have become corrupt. Structural changes are re-applied to ensure the database state is valid, then the completed transactions and independent updates are replayed to return the data to a consistent state.
Refer to Rapid Database Recovery for more information.
Full Recovery
Full database recovery is required when a major system or application failure has occurred causing data loss or corruption within the database and Rapid Recovery is either not enabled or is not possible, for example, because of a hardware failure. It is carried out from the Database Recovery menu of the tlmenu administration utility. The main steps are:
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Restore the last backup of the database using Database Recovery menu option 1.
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Restore all changes logged in clean logs since the last backup using Database Recovery menu option 2.
This procedure replays all After images from specified clean logs on the database. If more than one clean log has been generated since the back-up, then all clean logs are requested and restored in chronological order.
Refer to Transaction Logging Database Recovery for a step-by-step description of the procedure.