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Incrementally Updated Backup

Posted by FatDBA on January 1, 2013

Incrementally Updated Backups

Using this feature all changes between the SCN of the original image copy and the SCN of the incremental backup are applied to the image copy, winding it forward to make the equivalent of a new database image copy without the overhead of such a backup. The following example shows how this can be used.

RUN {
RECOVER COPY OF DATABASE WITH TAG ‘incr_backup’ UNTIL TIME ‘SYSDATE – 7’;
BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF COPY WITH TAG ‘incr_backup’ DATABASE;
}

The RECOVER COPY… line will not do anything until the script has been running for more than 7 days. The BACKUP INCREMENTAL line will perform a complete backup (level 0) the first day it is run, with all subsequent backups being level 1 incremental backups. After 7 days, the RECOVER COPY… line will start to take effect, merging all incremental backups older than 7 days into the level 0 backup, effectively moving the level 0 backup forward. The effect of this is that you will permanently have a 7 day recovery window with a 7 day old level 0 backup and 6 level 1 incremental backups. Notice that the tag must be used to identify which incremental backups apply to which image copies.

If you wanted to keep your image copy as up to date as possible you might do the following.

RUN {
BACKUP INCREMENTAL LEVEL 1 FOR RECOVER OF COPY WITH TAG ‘incr_backup’ DATABASE;
RECOVER COPY OF DATABASE WITH TAG ‘incr_backup’;
}

In this example the incremental backup is merged into the image copy as soon as it is completed.

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