Incrementally Updated Backups: A Basic Example

To create incremental backups for use in an incrementally updated backups strategy, you must use the BACKUP... FOR RECOVER OF COPY WITH TAG form of the BACKUP command. How the command works is best understood in the context of an example script that would implement the strategy.

This script, run on a regular basis, is all that is required to implement a strategy based on incrementally updated backups:
RUN {
RECOVER COPY OF DATABASE WITH TAG 'incr_update';
BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF COPY WITH TAG 'incr_update' DATABASE;
}

The syntax used in the script does not, however, make it clear how the strategy works. To understand the script and the strategy, it is necessary to understand the effects of these two commands when no datafile copies or incremental backups exist.


The RECOVER COPY OF DATABASE WITH TAG... command causes RMAN to apply any available incremental level 1 backups to a set of datafile copies with the specified tag.

If there is no incremental backup or no datafile copy, the command generates a message but does not generate an error.

The first time the script runs, this command has no effect, because there is neither a datafile copy nor a level 1 incremental backup.

The second time the script runs, there is a datafile copy (created by the first BACKUP command), but no incremental level 1 backup, so again, the command has no effect.

On the third run and all subsequent runs, there is a datafile copy and a level 1 incremental from the previous run, so the level 1 incremental is applied to the datafile copy, bringing the datafile copy up to the checkpoint SCN of the level 1 incremental.

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如果不想使用这种循环执行的方式，而是希望手动完成：
1.创建lv0的image copy
backup as copy incremental level 0 database
2.创建lv1的backup set
BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF COPY DATABASE

这样，当需要更新image copy的时候运行：
RECOVER COPY OF DATABASE

（以上3条语句可以加上tag参数）