Incremantal Backups with RMAN

Question

Hello, I was wondering if RMAN incremental backups are cumulative? If I do incrementals every night, would each night consist of every thing since the last full backup? Here is the script that I am using to perform my nightly incremental backups:
Retention policy is 7 days.
run{
allocate channel c1 device type disk format 'F:\rman_backups\ incremental\rman_incr_%n_%T_%s_%p.bak';
backup level 1 database plus archivelog;
allocate channel for maintenance device type disk;
delete archivelog until time 'sysdate - 7' backed up 2 times to disk;
delete obsolete device type disk;
Thank you

Answer 1

Hi David
What do you mean with "different backup levels"? The differences between the cumulative and the differential backup or what "has been backed up" after a level 1 (cumulative/differential) backup?
http://download-east.oracle.com/docs/cd/B10501_01/server.920/a96565/rcmsynta9.htm#78484
INCREMENTAL LEVEL = integer
Copies only those data blocks that have changed since the last incremental integer backup, where integer is any integer from 0 to 4. For example, in a level 2 backup RMAN backs up all blocks used since the most recent level 2, level 1, or level 0 backup.
This type of incremental backup is also called a differential backup to distinguish it from a cumulative backup.
A level 0 backup must exist as the base backup for an incremental strategy. An incremental backup at level 0 is identical in content to a full backup, but unlike a full backup the level 0 backup is considered a part of the incremental strategy.
If no level 0 backup exists when you run a level 1 or higher backup, then RMAN makes a level 0 backup automatically.
Oracle performs checks when attempting to create an incremental backup at a level greater than 0.
These checks ensure that the incremental backup is usable by a subsequent RECOVER command. Among the checks performed are:
    * A level 0 backup set must exist, or level 0 datafile copies must exist for each datafile in the BACKUP command. These backup sets must not be marked UNAVAILABLE.
If no level 0 backup exists, then RMAN automatically generates one.
    * Sufficient incremental backups taken since the level 0 must exist and be available such that the incremental backup to be created is usable.
If you specify INCREMENTAL, then in the backupSpec clause you must set one of the following parameters: DATAFILE, DATAFILECOPY, TABLESPACE, or DATABASE.
RMAN does not support incremental backups of control files, archived redo logs, or backup sets.
Note: You cannot make inconsistent incremental backups when the database is in NOARCHIVELOG mode.
Hence, you cannot generate incremental backups when a NOARCHIVELOG database is open and in use.Here you can find the "top" description about "Incremental Backups";
http://download-east.oracle.com/docs/cd/B10501_01/server.920/a96566/rcmconc1.htm#458838
Bye, Aron