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This chapter is from the book

This chapter is from the book

Backup and Recovery Tools

Recovery Manager (RMAN)

RMAN is an Oracle provided tool that allows you perform backup and recovery operations on the database. Using RMAN you can backup and restore datafiles, control files and archived redo log files.

RMAN operates using the recovery catalog to store metadata information about backup and recovery operations. Typically the recovery catalog is stored in a separate database. If you do not want to use the recovery catalog RMAN can use the target database control file to perform backup and recovery operations. Because most information in the recovery catalog is also available in the target database's control file, RMAN supports using the target database control file instead of a recovery catalog. The disadvantage of using the control file is that RMAN does not support restore or recovery when the control file is lost. To avoid this you should make frequent backups of the control file. Using the control file is especially appropriate for small databases where installation and administration of another database for the sole purpose of maintaining the recovery catalog is burdensome.

A single recovery catalog is able to store information for multiple target databases. Consequently, loss of the recovery catalog can be disastrous. You should back up the recovery catalog frequently. If the recovery catalog is destroyed and no backups of it are available, then you can partially reconstruct the catalog from the current control file or control file backups.

When you perform a backup using RMAN, information about the backup is stored in the catalog and the actual backups(physical files) are stored on disk or tape(requires media management software). When you use RMAN with a recovery catalog, the RMAN environment is comprised of the following components

  • RMAN executable

  • Recovery catalog database (Database to hold the catalog)

  • Recovery catalog schema in the recovery catalog database (Schema to hold the metadata information)

  • Optional Media Management Software (for tape backups)

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