In contrast to a full backup, an incremental backup copies only those data blocks that have changed since a previous backup. You can use RMAN to create incremental backups of datafiles, tablespaces, or the whole database. A full backup cannot be part of an incremental backup strategy; that is, it cannot be the parent for a subsequent incremental backup
Our findings (please kindly refer a question in Oracle forum):
For a brand new database (no backup had eve been performed):
Suppose the first backup is a RMAN full backup.
On the next backup, if a RMAN differential incremental level 1 backup is performed, a differential incremental level 0 backup would automatically performed instead.
Case 2:
Suppose:
On time T1: the database performed a differential incremental level 0 backup
On time T2: the database performed a full backup (not incremental level 0).
On time T3: the database performed a differential incremental level 1 backup
It is found that the backup at T2 would be used as the parent for T3.
On RMAN restore it would actually restore the full backup (taken on T2)
On RMAN recover, it would restore the incremental backup (taken on T3).
If multiple backups (full/level0/level1) were performed in the past, it is not crystal clear and could be confusing.
In Oracle (RMAN) world, we only take incr0 which is base backup. I don't use further level 1 as there is hit on restore times.
In your case, your incr0 would be base backup and incr1 would be use that base for subsequent backups.
I think most of the time people are confused as what is the difference between full and incr 0 in Oracle. None unless you take incr 1, but if you plan to take incr 1 then you must have incr 0 and not full. See https://www.pythian.com/blog/rman-full-backup-level-0-incrmental/
If you plan to to have different levels, I suggest you have different RMAN script for each and different client associated with that script - rest is just matter of scheduling at your own liking.
It is possible; you use 2 different clients/groups/schedules/policies. Each is used for RMAN script you call and where you define which level you are using.
In my tests, we found that RMAN backups are fast enough to make always full or incr0 backup only (our biggest pure Oracle DB is around 4TiB and the one under SAP is 7TiB; for last one my group runs some 5 hours which also includes cloning/replication).
ble1
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Posted February 20th, 2017 13:00
Incremental will always depend on full.
In Oracle (RMAN) world, we only take incr0 which is base backup. I don't use further level 1 as there is hit on restore times.
In your case, your incr0 would be base backup and incr1 would be use that base for subsequent backups.
I think most of the time people are confused as what is the difference between full and incr 0 in Oracle. None unless you take incr 1, but if you plan to take incr 1 then you must have incr 0 and not full. See https://www.pythian.com/blog/rman-full-backup-level-0-incrmental/
If you plan to to have different levels, I suggest you have different RMAN script for each and different client associated with that script - rest is just matter of scheduling at your own liking.