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Oracle Tips by Burleson |
Oracle 10g RMAN Change-Aware
Incremental Backups
In previous releases of the Oracle database, RMAN
had to examine every block in the data file to determine which
blocks had been changed when performing an incremental backup. The
time to perform an incremental backup was proportional to the size
of the data files. Therefore, performing an incremental backup on
a very large database could take some time, even if only a few
blocks were changed.
In Oracle 10g, you can create a block change
tracking file that records the blocks modified since the last
backup. RMAN uses the tracking file to determine which blocks to
include in the incremental backup. RMAN no longer needs to examine
the entire data file. The time to perform an incremental backup is
now proportional to the amount of content modified since the last
backup.
Here are the steps RMAN will perform to do an
incremental backup:
-
Read the Block Change Tracking File to
determine which blocks in the data file need to be read.
-
Scan only the changed blocks (See Figure
12.1) in the data file and then back them up.
Figure
12.7 Incremental Backup using Block Change Tracking File
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