Suppose you have a database running in NOARCHIVELOG mode. Disk 1 is damaged due to a media failure, and datafile #1 on this disk is lost.
There are two online log files containing sequence numbers 75 and 76, with the current log sequence 76.
The most recent backup was made at log sequence 73. Is it possible to completely recover this database? No.
Damaged Data files along with the available backup files
Explanation
If the DBA replaces datafile #1 with a backup copy made at log sequence 73, it cannot be made current with the rest of the database, which is currently at 76.
There are not enough logs available.
Online redo logs are not being archived. The current two logs, 75 and 76, at one time held sequence number 73. But each log is over-written at every log switch.
Since the redo log 73 was over-written, a whole database restore is necessary. Remember, if a database is running in
NOARCHIVELOG mode, you have to restore the whole database backup even though only one file has been corrupted or lost.
Steps for recovery
Click the Simulation button to see how to perform a NOARCHIVELOG database recovery.
You may also preview all steps.
No Archive Log Recovery Steps
The following code shows what you would see on your screen when you perform a NOARCHIVELOG database recovery.