Oracle Database 11 g - Online Public Access Catalog

CHAPTER 6 ■ BACKUP AND RECOVERY 289and standby databases directly from a live production database, with only an overhead interms of additional CPU and network utilization for the duplication process. RMAN simplycopies the target database files to the destination server (it can be the same server) over anetwork connection.Until the Oracle Database 11g release, duplicating a destination database with RMAN meantyou had to have all of the following:• A source database• A copy of the source database on the source database (or on disk)• A copy of the source database on the destination serverWhen you use the network-enabled active database duplication, the process of duplicating isconsiderably simpler. You don’t need any previously made backup of the source database, andyou are able to duplicate a live production database to a duplicate instance or create a physicalstandby database over the network without actually restoring a previously existing backup.You can perform this network-aware, backup-less database duplication either with DatabaseControl or through RMAN. You still use the RMAN duplicate database command, but with anew clause named from active database, to let RMAN know you aren’t using backups as thesource but are instead using the network for the database duplication. The database files aredirectly copied over the network connection from the source database to the new destinationdatabase.Unlike in the case of a normal backup-based database duplication, you don’t have to usethe until clause when performing an active database duplication. RMAN automatically selectsthe time based on when the copying of the online datafiles to the destination database iscompleted, so it can recover the datafiles to a consistent point in time. Because RMAN doesn’tcopy the online redo log files and apply them to the duplicate database, it must always performan incomplete recovery. RMAN can recover the duplicate database to the point in time of thelatest archived redo log on the source database.PrerequisitesHere are the requirements you must satisfy before starting active database duplication overthe network:• Both the target and destination databases must be on an identical operating systemplatform.• Oracle Net must be aware of both the target and duplicate instances.• Both the target and destination databases must have the same sysdba password,enforced through the use of password files.• The source database can be either in the open or in the mount state.• If the target database is open, it must be in archivelog mode.• If the target database is in the mount state, you must have shut it down cleanly beforebringing it up in the mount state.