What is a consistent backup?

What is a consistent backup?

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A consistent backup is a whole database backup (backup of the control file and all data files of a database) that does not require media recovery after being restored. In other words, a consistent backup does not require the application of redo data before it can be made consistent. It can be opened using the RESETLOGS option without performing media recovery. All data files in a consistent backup must have the same checkpoint system change number (SCN) in their headers, which must match the checkpoint information stored in the control file. They must not contain any change beyond the checkpoint SCN.

A consistent backup of a database can be taken only when the database is closed, and if the database was cleanly shut down, i.e., it was shut down using the SHUTDOWN NORMAL, SHUTDOWN IMMEDIATE, or SHUTDOWN TRANSACTIONAL command. If the database was shut down using the SHUTDOWN ABORT command, the backup will be an inconsistent backup and require recovery (application of redo data) to be consistent.

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