Oracle backup Basics

Oracle is divided into archive and non-archive modes. The difference between the two is the redo log processing. In archive mode, when a redo log is fully written, the content in the redo log is written to the archive file. After the redo log is written, the redo log can continue to be used, in non-archive mode, redo logs are overwritten directly. Archive files are generally required for restoration. database operations are recorded here, So production databases generally run in archive mode.

The storage location of RMAN backup also has two options: one is to back up directly to the disk, and the other is to back up to the tape. Currently, big companies generally use Symnatec Veritas master software for backup. This software extends the features and advantages of RMAN, making it easier to use.

The use of RMAN backup is also divided into catalog and nocatalog, that is, whether to use the recovery directory. If the recovery directory is not used, the control file is used as the catalog, each backup must write a lot of backup information into the control file. More and more backup information will be generated in the control file. Therefore, it is very important to back up the controlfile when using rman nocatalog for backup. If you use catalog mode, you need to create a catalog directory. When there are many databases, it is convenient to use catalog.

There are two types of RMAN backups: Full backup and Incremental backup. Full backup is applicable when the database is relatively small. If the database is large, Incremental backup is required because this can reduce the backup time.