Restore means using the backup files to replace the original files after a media failure.
Recovery
Recovery means bringing the database up to date using the restored files, archive logs and online redo logs.
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Wednesday, January 28, 2009
Monday, January 5, 2009
Crash Vs Instance Recovery
Crash Recovery Vs Instance Recovery
When the instance suddenly fail due to power outage or issuing shut abort, the instance requires recovery during next startup. Oracle will perform crash recovery up on restarting the database.
Crash Recovery involves two steps Cache recovery and transaction recovery.
Cache Recovery (Roll Forward) : The committed and Uncommitted data from the online redolog files are applied to the datafiles.
Transaction Recovery (Roll Back): The uncommitted data are rolled back from the datafiles.
In an RAC environment, one of the surviving instance performs the crash recovery of failed instance. This is known as instance recovery. In a single instance database, crash recovery and instance recovery are synonymous.
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When the instance suddenly fail due to power outage or issuing shut abort, the instance requires recovery during next startup. Oracle will perform crash recovery up on restarting the database.
Crash Recovery involves two steps Cache recovery and transaction recovery.
Cache Recovery (Roll Forward) : The committed and Uncommitted data from the online redolog files are applied to the datafiles.
Transaction Recovery (Roll Back): The uncommitted data are rolled back from the datafiles.
In an RAC environment, one of the surviving instance performs the crash recovery of failed instance. This is known as instance recovery. In a single instance database, crash recovery and instance recovery are synonymous.
Thanks
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