Tuesday, January 29, 2013

What is the difference between restoring and recovering?

Restoring the database involves copying backup files from the backup location to disk, sometimes it involves replacing damaged files etc., while recovery is the process of applying redo logs to the database in order to roll it forward. Database can be rolled forward toa specific point-in-time, or until the last transaction in the log files.

During restoration, RMAN decides which backup sets, datafiles, and archive logs are necessary for the database restoration and verifies their contents. No files are actually restored during this process.

Restoration of a datafile or a control file from backup involves retrieving the file onto disk from a backup location and making it available to the database server. While recovering a datafile involved takinhg a restored copy of the datafile and applying changes recorded in the redo logs.

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