The incremental level 0 backup for database is going more than expected:
INC LEVEL 0 229 GB.
But Re-run the backup successfully. backup size is:
INC LEVEl 0 219 GB.
why INC LEVEL 0 was 229 GB? i.e increase 10 GB in size?
NOTE: The RMAN metadata is not deleted.
Would need more information. Can you post the backup script and version of Oracle?
Compression is you first option. If you don't have advanced Compression, you could compression the backup yourself. Keep in mind this will slow recovery time.
BACKUP AS COMPRESSED BACKUPSET
So use BZIP2 instead of ZLIB if you can.