ora, listener.ora, and sqlnet.ora. However, these files are relatively static in nature,
and they can easily be backed up and restored using a traditional backup method such as the
Unix cp command.
Backup Types
RMAN supports a number of different backup methods, depending on your availability needs,
the desired size of your recovery window, and the amount of downtime you can endure while the
database or a part of the database is involved in a recovery operation.
Consistent and Inconsistent Backups
A physical backup can be classified by being a consistent or an inconsistent backup. In a consistent
backup, all datafiles have the same SCN; in other words, all changes in the redo logs have been
applied to the datafiles. Because an open database with no uncommitted transactions may have
some dirty blocks in the buffer cache, it is rare that an open database backup can be considered
consistent. As a result, consistent backups are taken when the database is shut down normally or
in a MOUNT state.
In contrast, an inconsistent backup is performed while the database is open and users are
accessing the database. Because the SCNs of the datafiles typically do not match when an
inconsistent backup is taking place, a recovery operation performed using an inconsistent backup
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422 Oracle Database 11g DBA Handbook
must rely on both archived and online redo log files to bring the database into a consistent state
before it is opened.
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