Why incremental backup ?
The most important reason for doing incremental backups is associated with data warehouse environments, where many operations are done in NOLOGGING mode and data changes do not go to the archived log files.
Considering the massive size of data warehouses today, and the fact that most of the data in them does not change, full backups are neither desirable nor practical. Therefore , doing incremental backups in RMAN is an ideal alternative.
WhyDBAs dis not like incremental backup in 9i ?
Oracle does full scan for finding changes in 9i which generates some performance problem.This is why most DBAs did not like incremental backup in 9i.
What is new with 10g incremental backup ?
Block changes can be tracked in 10g which means that Oracle does not need to do full scan anymore to find out changes.
To enable track changing run the following command.
alter database enable block change tracking using file '/rman_bkups/change.log';
To disable block track change.
alter database disable block change tracking;