Does rman take incremental lvl 0 backup in noarchivelog mode?

In this article, i am going to test rman level 0 incremental backup in noarchivelog mode.

For long time, i had this thing in my mind to test this scenario.Why because, i know that incremental backup happens when the database is online and it is more of a ground level hot backup or online backup we can say!

Are you curious about it? Lets see

My database is already in archivelog mode

SQL> archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     315
Next log sequence to archive   317
Current log sequence           317

I bounce the database and change database to noarchivelog mode

SQL> startup mount;
ORACLE instance started.

Total System Global Area 1644167168 bytes
Fixed Size                  2925024 bytes
Variable Size             989859360 bytes
Database Buffers          637534208 bytes
Redo Buffers               13848576 bytes
Database mounted.
SQL> alter database noarchivelog;

Database altered.

SQL> alter database open;

Database altered.

During first run,backup fails with existing archive sequence file missing error

backup incremental level 0 database plus archivelog delete input;
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup plus archivelog command at 02/18/2021 13:30:23
RMAN-06059: expected archived log not found, loss of archived log compromises recoverability
ORA-19625: error identifying file /data01/ORCL12X/archivelog/2021_01_17/o1_mf_1_229_j07ss05h_.arc
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

So i delete the expired archivelog backup to guide rman not to bother about very old archives

RMAN> crosscheck archivelog all;
Crosschecked 85 objects

RMAN> delete expired archivelog all;
Deleted 85 EXPIRED objects

Now i trigger only incremental level 0 backup without archivelog clause

RMAN> backup incremental level 0 database;

Starting backup at 18-FEB-21
using channel ORA_DISK_1
using channel ORA_DISK_2
using channel ORA_DISK_3
using channel ORA_DISK_4
using channel ORA_DISK_5
using channel ORA_DISK_6
using channel ORA_DISK_7
using channel ORA_DISK_8
using channel ORA_DISK_9
using channel ORA_DISK_10
using channel ORA_DISK_11
using channel ORA_DISK_12
using channel ORA_DISK_13
using channel ORA_DISK_14
using channel ORA_DISK_15
using channel ORA_DISK_16
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup command at 02/18/2021 13:39:48
RMAN-06149: cannot BACKUP DATABASE in NOARCHIVELOG mode

RMAN clearly leaves an error message saying that “cannot backup database in noarchivelog mode”

So this made me confidence and given me a solid evidence that inc backup fails in noarchivelog mode

Testing always clear scepticism!

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