Friday 5 May 2017

Oracle Database Administrator Interview Questions on RMAN


1.What is the difference between recovery catalog and Nocatalog backup in RMAN?

NoCatalog Backup:

ByDefault RMAN connects to the target database in Nocatalog Mode.
In Nocatalog Mode, Backup Information and Metadata related to RMAN is stored in target database controlfile.

Catalog Backup:

A recovery catalog is a schema created in a separate database that contains metadata obtained from the target control file.
In recovery catalog we can store rman scripts.

We can store metadata about multiple incarnations of a single target database in the catalog.
Recovery catalog is central and can have information of many databases.
If the control file is lost and must be restored from backup, the backup configuration information is available when the database is not mounted.

2.What are the differences between crosscheck and validate commands?

Validate command is to examine a backup set and report whether it can be restored. RMAN scans all of the backup pieces in the specified backup sets and looks at the checksum to verify that the contents are intact so that backup can be successfully restored if necessary.

Crosscheck command is to verify the status of backups and copies recorded in the RMAN repository against media such as disk or tape. The crosscheck command only processes files created on the same device type as the channel running crosscheck.

3.What is obsolete backup & expired backup?

A status of “expired” means that the backup piece or backup set is not found in the backup destination.

A status of “obsolete” means the backup piece is still available, but it is no longer needed. The backup piece is no longer needed since RMAN has been configured to no longer need this piece after so many days have elapsed, or so many backups have been performed.

4.What is the difference between hot backup & RMAN backup?

We need to put the database in Backup mode for Hot  Backup. RMAN Backup does not need the database to be in Backup mode.

5. Which Tables are have information required for RMAN list & report commands ?
 V$BACKUP_FILES and recovery catalog views e.g.,  RC_DATAFILE_COPY or RC_ARCHIVED_LOG.

Below tables contain RMAN Catalog information:


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