I have R12.1.3 E-Business Suite system which has 2 node RAC database on AIX 6.1 with 11.2.0.1.6 version

Our database size almost 15T and We need to backup this system twice in a day. Because of the backup duration time(We are using 16 channel and full backup time almost 2,5 hours) That’s why We decided to pass Cumulative Incremental backup strategy for this system.

We take Level 0(full) backup on weekend and We take Level 1 Cumulative Incremental  backup during working days.

We notice that after some days passed, Cumulative Incremental   backup size rise up from 1T to 11T. It start to work like full Level0 backup time duration and backup size.

We have been worked with Oracle Support. The reason for this is that there is a limit on the number of backups that BCT can store, these are 8 by default which mean After 8 Incremental backup you need to get Level0 backup or you need to change hidden parameter _bct_bitmaps_per_file dynamicly

The limit is set by the “_bct_bitmaps_per_file” parameter. This parameter sets the number of bitmaps to be stored for each datafile, and its default value is 8.  As I mention before, In order to avoid this issue one can either run less than 8 incremental backups or can increase the “_bct_bitmaps_per_file” parameter.

Please refer to:
How Many Incremental Backups Can Be Taken When BCT Is Enabled ? [ID 452455.1]